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• Subtyping and assignment in Java

  - by Danrex

  Arghh I just know people are going to hate me for asking this... I was just playing around with inheritance and I noticed you can instantiate a subclass object in one of two ways when you write code. So then I wondered if there is any functional difference between these two methods. So in the code below, does this produce the exact same result...a MountainBike object, or is there some difference I should know about? Bicycle is the superclass for this example. If I do Bicycle bike or MountainBike bike I am effectively making a MountainBike due to new MountainBike()? So basically the difference is just semantics at this point? Bicycle bike = new MountainBike(); MountainBike bike = new MountainBike();

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• Java - Basic use of arrays

  - by javaisjusttoohard

  This is a basic question but I do need some help. Given two arrays of ints, a and b, return true if they have the same first element or they have the same last element. Both arrays will be length 1 or more. commonEnd({1, 2, 3}, {7, 3}) ? true commonEnd({1, 2, 3}, {7, 3, 2}) ? false commonEnd({1, 2, 3}, {1, 3}) ? true I have the following code but it wont compile: public boolean commonEnd(int[] a, int[] b) { if(a[0] == b[0] || a[a.length-1] ==b[b.length-1]) return true; }

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• Java Space on Parleys

  - by Yolande Poirier

  Now available! A great selection of JavaOne 2010 and JVM Language Summit 2010 sessions as well as Oracle Technology Network TechCasts on the new Java Space on Parleys website. Oracle partnered with Stephan Janssen, founder of Parleys to make this happen. Parleys website offers a user friendly experience to view online content. You can download some of the talks to your desktop or watch them on the go on mobile devices. The current selection is a well of expertise from top Java luminaries and Oracle experts. JavaOne 2010 sessions: ·        Best practices for signing code by Sean Mullan   ·        Building software using rich client platforms by Rickard Thulin ·        Developing beyond the component libraries by Ryan Cuprak ·        Java API for keyhole markup language by Florian Bachmann ·        Avoiding common user experience anti-patterns by Burk Hufnagel ·        Accelerating Java workloads via GPUs by Gary Frost JVM Languages Summit 2010 sessions: ·      Mixed language project compilation in Eclipse by Andy Clement  ·      Gathering the threads by John Rose  ·      LINQ: language features for concurrency by Neal Gafter  ·      Improvements in OpenJDK useful for JVM languages by Eric Caspole  ·      Symmetric Multilanguage - VM Architecture by Oleg Pliss  Special interviews with Oracle experts on product innovations: ·      Ludovic Champenois, Java EE architect on Glassfish 3.1 and Java EE. ·      John Jullion-Ceccarelli and Martin Ryzl on NetBeans IDE 6.9 You can chose to listen to a section of talks using the agenda view and search for related content while watching a presentation.  Enjoy the Java content and vote on it! 

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• Duke's Choice Award Ceremony

  - by Tori Wieldt

  The 2012 Duke's Choice Awards winners and their creative, Java-based technologies and Java community contributions were honored after the Sunday night JavaOne keynotes. Sharat Chander, Group Director for Java Technology Outreach, presented the awards. "Having the community participate directly in both submission and selection truly shows how we are driving exposure of the innovation happening in the Java community," he said. Apache Software Foundation Hadoop Project The Apache Software Foundation’s Hadoop project, written in Java, provides a framework for distributed processing of big data sets across clusters of computers, ranging from a few servers to thousands of machines. This harnessing of large data pools allows organizations to better understand and improve their business. AgroSense Project Improving farming methods to feed a hungry world is the goal of AgroSense, an open source farm information management system built in Java and the NetBeans platform. AgroSense enables farmers, agribusinesses, suppliers and others to develop modular applications that will easily exchange information through a common underlying NetBeans framework. JDuchess Rather than focus on a specific geographic area like most Java User Groups (JUGs), JDuchess fosters the participation of women in the Java community worldwide. The group has more than 500 members in 60 countries, and provides a platform through which women can connect with each other and get involved in all aspects of the Java community. Jelastic, Inc. Moving existing Java applications to the cloud can be a daunting task, but startup Jelastic, Inc. offers the first all-Java platform-as-a-service (PaaS) that enables existing Java applications to be deployed in the cloud without code changes or lock-in. Liquid Robotics Robotics – Liquid Robotics is an ocean data services provider whose Wave Glider technology collects information from the world’s oceans for application in government, science and commercial applications. The organization features the “father of Java” James Gosling as its chief software architect. London Java Community The second user group receiving a Duke’s Choice Award this year, the London Java Community (LJC) and its users have been active in the OpenJDK, the Java Community Process (JCP) and other efforts within the global Java community. NATO The first-ever Community Choice Award goes to the MASE Integrated Console Environment (MICE) in use at NATO. Built in Java on the NetBeans platform, MICE provides a high-performance visualization environment for conducting air defense and battle-space operations. Parleys.com E-learning specialist Parleys.com, based in Brussels, Belgium, uses Java technologies to bring online classes and full IT conferences to desktops, laptops, tablets and mobile devices. Parleys.com has hosted more than 1,700 conferences—including Devoxx and JavaOne—for more than 800,000 unique visitors. Student Nokia Developer Group This year’s student winner, Ram Kashyap, is the founder and president of the Nokia Student Network, and was profiled in the “The New Java Developers” feature in the March/April 2012 issue of Java Magazine. Since then, Ram has maintained a hectic pace, graduating from the People’s Education Society Institute of Technology in Bangalore, India, while working on a Java mobile startup and training students on Java ME. United Nations High Commissioner for Refugees The United Nations High Commissioner for Refugees (UNHCR) is on the front lines of crises around the world, from civil wars to natural disasters. To help facilitate its mission of humanitarian relief, the UNHCR has developed a light-client Java application on the NetBeans platform. The Level One registration tool enables the UNHCR to collect information on the number of refugees and their water, food, housing, health, and other needs in the field, and combines that with geocoding information from various sources. This enables the UNHCR to deliver the appropriate kind and amount of assistance where it is needed. You can read more about the winners in the current issue of Java Magazine.

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• "Class ref in pre-verified class resolved to unexpected implementation" when running android tests i

  - by Mike

  I have a module that builds an app called MyApp. I have another that builds some testcases for that app, called MyAppTests. They both build their own APKs, and they both work fine from within my IDE. I'd like to build them using ant so that I can take advantage of continuous integration. Building the app module works fine. I'm having difficulty getting the Test module to compile and run. Using Christopher's tip from a previous question, I used android create test-project -p MyAppTests -m ../MyApp -n MyAppTests to create the necessary build files to build and run my test project. This seems to work great (once I remove an unnecessary test case that it constructed for me and revert my AndroidManifest.xml to the one I was using before it got replaced by android create), but I have two problems. The first problem: The project doesn't compile because it's missing libraries. $ ant run-tests Buildfile: build.xml [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -install-tested-project: [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 1 source file to /Users/mike/Projects/myapp/android/MyApp/bin/classes -dex: [echo] Converting compiled files and external libraries into /Users/mike/Projects/myapp/android/MyApp/bin/classes.dex... [echo] -package-resources: [echo] Packaging resources [aaptexec] Creating full resource package... -package-debug-sign: [apkbuilder] Creating MyApp-debug-unaligned.apk and signing it with a debug key... [apkbuilder] Using keystore: /Users/mike/.android/debug.keystore debug: [echo] Running zip align on final apk... [echo] Debug Package: /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk install: [echo] Installing /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk onto default emulator or device... [exec] 1567 KB/s (288354 bytes in 0.179s) [exec] pkg: /data/local/tmp/MyApp-debug.apk [exec] Success -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... [mkdir] Created dir: /Users/mike/Projects/myapp/android/MyAppTests/gen [mkdir] Created dir: /Users/mike/Projects/myapp/android/MyAppTests/bin [mkdir] Created dir: /Users/mike/Projects/myapp/android/MyAppTests/bin/classes -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 5 source files to /Users/mike/Projects/myapp/android/MyAppTests/bin/classes [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:4: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:8: package com.google.gson does not exist [javac] import com.google.gson.JsonElement; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:9: package com.google.gson does not exist [javac] import com.google.gson.JsonParser; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:11: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class GsonTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:6: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:7: package roboguice.util does not exist [javac] import roboguice.util.RoboLooperThread; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:11: package com.google.gson does not exist [javac] import com.google.gson.JsonObject; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:15: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class HttpTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:4: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:12: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class LinksTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:4: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:5: package roboguice.util does not exist [javac] import roboguice.util.RoboAsyncTask; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:6: package roboguice.util does not exist [javac] import roboguice.util.RoboLooperThread; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:12: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class SafeAsyncTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectResource': class file for roboguice.inject.InjectResource not found [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectResource' [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView': class file for roboguice.inject.InjectView not found [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView' [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView' [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView' [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:15: cannot find symbol [javac] symbol : class JsonParser [javac] location: class com.myapp.test.GsonTest [javac] final JsonParser parser = new JsonParser(); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:15: cannot find symbol [javac] symbol : class JsonParser [javac] location: class com.myapp.test.GsonTest [javac] final JsonParser parser = new JsonParser(); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:18: cannot find symbol [javac] symbol : class JsonElement [javac] location: class com.myapp.test.GsonTest [javac] final JsonElement e = parser.parse(s); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:20: cannot find symbol [javac] symbol : class JsonElement [javac] location: class com.myapp.test.GsonTest [javac] final JsonElement e2 = parser.parse(s2); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:19: cannot find symbol [javac] symbol : method getInstrumentation() [javac] location: class com.myapp.test.HttpTest [javac] assertEquals("MyApp", getInstrumentation().getTargetContext().getResources().getString(com.myapp.R.string.app_name)); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:62: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.HttpTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:82: cannot find symbol [javac] symbol : method assertTrue(java.lang.String,boolean) [javac] location: class com.myapp.test.HttpTest [javac] assertTrue(result[0], result[0].contains("Search")); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:87: cannot find symbol [javac] symbol : class JsonObject [javac] location: class com.myapp.test.HttpTest [javac] final JsonObject[] result = {null}; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:90: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.HttpTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:117: cannot find symbol [javac] symbol : class JsonObject [javac] location: class com.myapp.test.HttpTest [javac] final JsonObject[] result = {null}; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:120: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.HttpTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:27: cannot find symbol [javac] symbol : method assertTrue(boolean) [javac] location: class com.myapp.test.LinksTest [javac] assertTrue(m.matches()); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:28: cannot find symbol [javac] symbol : method assertEquals(java.lang.String,java.lang.String) [javac] location: class com.myapp.test.LinksTest [javac] assertEquals( map.get(url), m.group(1) ); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:19: cannot find symbol [javac] symbol : method getInstrumentation() [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals("MyApp", getInstrumentation().getTargetContext().getString(com.myapp.R.string.app_name)); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:27: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:65: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:74: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:105: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:113: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:144: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:154: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:187: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/StoriesTest.java:11: cannot access roboguice.activity.GuiceListActivity [javac] class file for roboguice.activity.GuiceListActivity not found [javac] public class StoriesTest extends ActivityUnitTestCase<Stories> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/StoriesTest.java:21: cannot access roboguice.application.GuiceApplication [javac] class file for roboguice.application.GuiceApplication not found [javac] setApplication( new MyApplication( getInstrumentation().getTargetContext() ) ); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/StoriesTest.java:22: incompatible types [javac] found : com.myapp.activity.Stories [javac] required: android.app.Activity [javac] final Activity activity = startActivity(intent, null, null); [javac] ^ [javac] 39 errors [javac] 6 warnings BUILD FAILED /opt/local/android-sdk-mac/platforms/android-1.6/templates/android_rules.xml:248: Compile failed; see the compiler error output for details. Total time: 24 seconds That's not a hard problem to solve. I'm not sure it's the right thing to do, but I copied the missing libraries (roboguice and gson) from the MyApp/libs directory to the MyAppTests/libs directory and everything seems to compile fine. But that leads to the second problem, which I'm currently stuck on. The tests compile fine but they won't run: $ cp ../MyApp/libs/gson-r538.jar libs/ $ cp ../MyApp/libs/roboguice-1.1-SNAPSHOT.jar libs/ 0 10:23 /Users/mike/Projects/myapp/android/MyAppTests $ ant run-testsBuildfile: build.xml [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -install-tested-project: [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 1 source file to /Users/mike/Projects/myapp/android/MyApp/bin/classes -dex: [echo] Converting compiled files and external libraries into /Users/mike/Projects/myapp/android/MyApp/bin/classes.dex... [echo] -package-resources: [echo] Packaging resources [aaptexec] Creating full resource package... -package-debug-sign: [apkbuilder] Creating MyApp-debug-unaligned.apk and signing it with a debug key... [apkbuilder] Using keystore: /Users/mike/.android/debug.keystore debug: [echo] Running zip align on final apk... [echo] Debug Package: /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk install: [echo] Installing /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk onto default emulator or device... [exec] 1396 KB/s (288354 bytes in 0.201s) [exec] pkg: /data/local/tmp/MyApp-debug.apk [exec] Success -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 5 source files to /Users/mike/Projects/myapp/android/MyAppTests/bin/classes [javac] Note: /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java uses unchecked or unsafe operations. [javac] Note: Recompile with -Xlint:unchecked for details. -dex: [echo] Converting compiled files and external libraries into /Users/mike/Projects/myapp/android/MyAppTests/bin/classes.dex... [echo] -package-resources: [echo] Packaging resources [aaptexec] Creating full resource package... -package-debug-sign: [apkbuilder] Creating MyAppTests-debug-unaligned.apk and signing it with a debug key... [apkbuilder] Using keystore: /Users/mike/.android/debug.keystore debug: [echo] Running zip align on final apk... [echo] Debug Package: /Users/mike/Projects/myapp/android/MyAppTests/bin/MyAppTests-debug.apk install: [echo] Installing /Users/mike/Projects/myapp/android/MyAppTests/bin/MyAppTests-debug.apk onto default emulator or device... [exec] 1227 KB/s (94595 bytes in 0.075s) [exec] pkg: /data/local/tmp/MyAppTests-debug.apk [exec] Success run-tests: [echo] Running tests ... [exec] [exec] android.test.suitebuilder.TestSuiteBuilder$FailedToCreateTests:INSTRUMENTATION_RESULT: shortMsg=Class ref in pre-verified class resolved to unexpected implementation [exec] INSTRUMENTATION_RESULT: longMsg=java.lang.IllegalAccessError: Class ref in pre-verified class resolved to unexpected implementation [exec] INSTRUMENTATION_CODE: 0 BUILD SUCCESSFUL Total time: 38 seconds Any idea what's causing the "Class ref in pre-verified class resolved to unexpected implementation" error?

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• Can't build and run an android test project created using "ant create test-project" when tested proj

  - by Mike

  I have a module that builds an app called MyApp. I have another that builds some testcases for that app, called MyAppTests. They both build their own APKs, and they both work fine from within my IDE. I'd like to build them using ant so that I can take advantage of continuous integration. Building the app module works fine. I'm having difficulty getting the Test module to compile and run. Using Christopher's tip from a previous question, I used android create test-project -p MyAppTests -m ../MyApp -n MyAppTests to create the necessary build files to build and run my test project. This seems to work great (once I remove an unnecessary test case that it constructed for me and revert my AndroidManifest.xml to the one I was using before it got replaced by android create), but I have two problems. The first problem: The project doesn't compile because it's missing libraries. $ ant run-tests Buildfile: build.xml [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -install-tested-project: [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 1 source file to /Users/mike/Projects/myapp/android/MyApp/bin/classes -dex: [echo] Converting compiled files and external libraries into /Users/mike/Projects/myapp/android/MyApp/bin/classes.dex... [echo] -package-resources: [echo] Packaging resources [aaptexec] Creating full resource package... -package-debug-sign: [apkbuilder] Creating MyApp-debug-unaligned.apk and signing it with a debug key... [apkbuilder] Using keystore: /Users/mike/.android/debug.keystore debug: [echo] Running zip align on final apk... [echo] Debug Package: /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk install: [echo] Installing /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk onto default emulator or device... [exec] 1567 KB/s (288354 bytes in 0.179s) [exec] pkg: /data/local/tmp/MyApp-debug.apk [exec] Success -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... [mkdir] Created dir: /Users/mike/Projects/myapp/android/MyAppTests/gen [mkdir] Created dir: /Users/mike/Projects/myapp/android/MyAppTests/bin [mkdir] Created dir: /Users/mike/Projects/myapp/android/MyAppTests/bin/classes -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 5 source files to /Users/mike/Projects/myapp/android/MyAppTests/bin/classes [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:4: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:8: package com.google.gson does not exist [javac] import com.google.gson.JsonElement; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:9: package com.google.gson does not exist [javac] import com.google.gson.JsonParser; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:11: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class GsonTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:6: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:7: package roboguice.util does not exist [javac] import roboguice.util.RoboLooperThread; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:11: package com.google.gson does not exist [javac] import com.google.gson.JsonObject; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:15: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class HttpTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:4: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:12: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class LinksTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:4: package roboguice.test does not exist [javac] import roboguice.test.RoboUnitTestCase; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:5: package roboguice.util does not exist [javac] import roboguice.util.RoboAsyncTask; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:6: package roboguice.util does not exist [javac] import roboguice.util.RoboLooperThread; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:12: cannot find symbol [javac] symbol: class RoboUnitTestCase [javac] public class SafeAsyncTest extends RoboUnitTestCase<MyApplication> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectResource': class file for roboguice.inject.InjectResource not found [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectResource' [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView': class file for roboguice.inject.InjectView not found [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView' [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView' [javac] /Users/mike/Projects/myapp/android/MyApp/bin/classes/com/myapp/activity/Stories.class: warning: Cannot find annotation method 'value()' in type 'roboguice.inject.InjectView' [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:15: cannot find symbol [javac] symbol : class JsonParser [javac] location: class com.myapp.test.GsonTest [javac] final JsonParser parser = new JsonParser(); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:15: cannot find symbol [javac] symbol : class JsonParser [javac] location: class com.myapp.test.GsonTest [javac] final JsonParser parser = new JsonParser(); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:18: cannot find symbol [javac] symbol : class JsonElement [javac] location: class com.myapp.test.GsonTest [javac] final JsonElement e = parser.parse(s); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:20: cannot find symbol [javac] symbol : class JsonElement [javac] location: class com.myapp.test.GsonTest [javac] final JsonElement e2 = parser.parse(s2); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:19: cannot find symbol [javac] symbol : method getInstrumentation() [javac] location: class com.myapp.test.HttpTest [javac] assertEquals("MyApp", getInstrumentation().getTargetContext().getResources().getString(com.myapp.R.string.app_name)); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:62: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.HttpTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:82: cannot find symbol [javac] symbol : method assertTrue(java.lang.String,boolean) [javac] location: class com.myapp.test.HttpTest [javac] assertTrue(result[0], result[0].contains("Search")); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:87: cannot find symbol [javac] symbol : class JsonObject [javac] location: class com.myapp.test.HttpTest [javac] final JsonObject[] result = {null}; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:90: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.HttpTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:117: cannot find symbol [javac] symbol : class JsonObject [javac] location: class com.myapp.test.HttpTest [javac] final JsonObject[] result = {null}; [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/HttpTest.java:120: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.HttpTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:27: cannot find symbol [javac] symbol : method assertTrue(boolean) [javac] location: class com.myapp.test.LinksTest [javac] assertTrue(m.matches()); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/LinksTest.java:28: cannot find symbol [javac] symbol : method assertEquals(java.lang.String,java.lang.String) [javac] location: class com.myapp.test.LinksTest [javac] assertEquals( map.get(url), m.group(1) ); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:19: cannot find symbol [javac] symbol : method getInstrumentation() [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals("MyApp", getInstrumentation().getTargetContext().getString(com.myapp.R.string.app_name)); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:27: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:65: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:74: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:105: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:113: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:144: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:154: cannot find symbol [javac] symbol : class RoboLooperThread [javac] location: class com.myapp.test.SafeAsyncTest [javac] new RoboLooperThread() { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java:187: cannot find symbol [javac] symbol : method assertEquals(com.myapp.test.SafeAsyncTest.State,com.myapp.test.SafeAsyncTest.State) [javac] location: class com.myapp.test.SafeAsyncTest [javac] assertEquals(State.TEST_SUCCESS,state[0]); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/StoriesTest.java:11: cannot access roboguice.activity.GuiceListActivity [javac] class file for roboguice.activity.GuiceListActivity not found [javac] public class StoriesTest extends ActivityUnitTestCase<Stories> { [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/StoriesTest.java:21: cannot access roboguice.application.GuiceApplication [javac] class file for roboguice.application.GuiceApplication not found [javac] setApplication( new MyApplication( getInstrumentation().getTargetContext() ) ); [javac] ^ [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/StoriesTest.java:22: incompatible types [javac] found : com.myapp.activity.Stories [javac] required: android.app.Activity [javac] final Activity activity = startActivity(intent, null, null); [javac] ^ [javac] 39 errors [javac] 6 warnings BUILD FAILED /opt/local/android-sdk-mac/platforms/android-1.6/templates/android_rules.xml:248: Compile failed; see the compiler error output for details. Total time: 24 seconds That's not a hard problem to solve. I'm not sure it's the right thing to do, but I copied the missing libraries (roboguice and gson) from the MyApp/libs directory to the MyAppTests/libs directory and everything seems to compile fine. But that leads to the second problem, which I'm currently stuck on. The tests compile fine but they won't run: $ cp ../MyApp/libs/gson-r538.jar libs/ $ cp ../MyApp/libs/roboguice-1.1-SNAPSHOT.jar libs/ 0 10:23 /Users/mike/Projects/myapp/android/MyAppTests $ ant run-testsBuildfile: build.xml [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -install-tested-project: [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.6 [setup] API level: 4 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 1 source file to /Users/mike/Projects/myapp/android/MyApp/bin/classes -dex: [echo] Converting compiled files and external libraries into /Users/mike/Projects/myapp/android/MyApp/bin/classes.dex... [echo] -package-resources: [echo] Packaging resources [aaptexec] Creating full resource package... -package-debug-sign: [apkbuilder] Creating MyApp-debug-unaligned.apk and signing it with a debug key... [apkbuilder] Using keystore: /Users/mike/.android/debug.keystore debug: [echo] Running zip align on final apk... [echo] Debug Package: /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk install: [echo] Installing /Users/mike/Projects/myapp/android/MyApp/bin/MyApp-debug.apk onto default emulator or device... [exec] 1396 KB/s (288354 bytes in 0.201s) [exec] pkg: /data/local/tmp/MyApp-debug.apk [exec] Success -compile-tested-if-test: -dirs: [echo] Creating output directories if needed... -resource-src: [echo] Generating R.java / Manifest.java from the resources... -aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 5 source files to /Users/mike/Projects/myapp/android/MyAppTests/bin/classes [javac] Note: /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/SafeAsyncTest.java uses unchecked or unsafe operations. [javac] Note: Recompile with -Xlint:unchecked for details. -dex: [echo] Converting compiled files and external libraries into /Users/mike/Projects/myapp/android/MyAppTests/bin/classes.dex... [echo] -package-resources: [echo] Packaging resources [aaptexec] Creating full resource package... -package-debug-sign: [apkbuilder] Creating MyAppTests-debug-unaligned.apk and signing it with a debug key... [apkbuilder] Using keystore: /Users/mike/.android/debug.keystore debug: [echo] Running zip align on final apk... [echo] Debug Package: /Users/mike/Projects/myapp/android/MyAppTests/bin/MyAppTests-debug.apk install: [echo] Installing /Users/mike/Projects/myapp/android/MyAppTests/bin/MyAppTests-debug.apk onto default emulator or device... [exec] 1227 KB/s (94595 bytes in 0.075s) [exec] pkg: /data/local/tmp/MyAppTests-debug.apk [exec] Success run-tests: [echo] Running tests ... [exec] [exec] android.test.suitebuilder.TestSuiteBuilder$FailedToCreateTests:INSTRUMENTATION_RESULT: shortMsg=Class ref in pre-verified class resolved to unexpected implementation [exec] INSTRUMENTATION_RESULT: longMsg=java.lang.IllegalAccessError: Class ref in pre-verified class resolved to unexpected implementation [exec] INSTRUMENTATION_CODE: 0 BUILD SUCCESSFUL Total time: 38 seconds Any idea what's causing the "Class ref in pre-verified class resolved to unexpected implementation" error?

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• Java map / nio / NFS issue causing a VM fault: "a fault occurred in a recent unsafe memory access op

  - by Matthew Bloch

  I have written a parser class for a particular binary format (nfdump if anyone is interested) which uses java.nio's MappedByteBuffer to read through files of a few GB each. The binary format is just a series of headers and mostly fixed-size binary records, which are fed out to the called by calling nextRecord(), which pushes on the state machine, returning null when it's done. It performs well. It works on a development machine. On my production host, it can run for a few minutes or hours, but always seems to throw "java.lang.InternalError: a fault occurred in a recent unsafe memory access operation in compiled Java code", fingering one of the Map.getInt, getShort methods, i.e. a read operation in the map. The uncontroversial (?) code that sets up the map is this: /** Set up the map from the given filename and position */ protected void open() throws IOException { // Set up buffer, is this all the flexibility we'll need? channel = new FileInputStream(file).getChannel(); MappedByteBuffer map1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size()); map1.load(); // we want the whole thing, plus seems to reduce frequency of crashes? map = map1; // assumes the host writing the files is little-endian (x86), ought to be configurable map.order(java.nio.ByteOrder.LITTLE_ENDIAN); map.position(position); } and then I use the various map.get* methods to read shorts, ints, longs and other sequences of bytes, before hitting the end of the file and closing the map. I've never seen the exception thrown on my development host. But the significant point of difference between my production host and development is that on the former, I am reading sequences of these files over NFS (probably 6-8TB eventually, still growing). On my dev machine, I have a smaller selection of these files locally (60GB), but when it blows up on the production host it's usually well before it gets to 60GB of data. Both machines are running java 1.6.0_20-b02, though the production host is running Debian/lenny, the dev host is Ubuntu/karmic. I'm not convinced that will make any difference. Both machines have 16GB RAM, and are running with the same java heap settings. I take the view that if there is a bug in my code, there is enough of a bug in the JVM not to throw me a proper exception! But I think it is just a particular JVM implementation bug due to interactions between NFS and mmap, possibly a recurrence of 6244515 which is officially fixed. I already tried adding in a "load" call to force the MappedByteBuffer to load its contents into RAM - this seemed to delay the error in the one test run I've done, but not prevent it. Or it could be coincidence that was the longest it had gone before crashing! If you've read this far and have done this kind of thing with java.nio before, what would your instinct be? Right now mine is to rewrite it without nio :)

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• How can I pipe input to a Java app with Perl?

  - by user319479

  I need to write a Perl script that pipes input into a Java program. This is related to this, but that didn't help me. My issue is that the Java app doesn't get the print statements until I close the handle. What I found online was that $| needs to be set to something greater than 0, in which case newline characters will flush the buffer. This still doesn't work. This is the script: #! /usr/bin/perl -w use strict; use File::Basename; $|=1; open(TP, "| java -jar test.jar") or die "fail"; sleep(2); print TP "this is test 1\n"; print TP "this is test 2\n"; print "tests printed, waiting 5s\n"; sleep(5); print "wait over. closing handle...\n"; close TP; print "closed.\n"; print "sleeping for 5s...\n"; sleep(5); print "script finished!\n"; exit And here is a sample Java app: import java.util.Scanner; public class test{ public static void main( String[] args ){ Scanner sc = new Scanner( System.in ); int crashcount = 0; while( true ){ try{ String input = sc.nextLine(); System.out.println( ":: INPUT: " + input ); if( "bananas".equals(input) ){ break; } } catch( Exception e ){ System.out.println( ":: EXCEPTION: " + e.toString() ); crashcount++; if( crashcount == 5 ){ System.out.println( ":: Looks like stdin is broke" ); break; } } } System.out.println( ":: IT'S OVER!" ); return; } } The Java app should respond to receiving the test prints immediately, but it doesn't until the close statement in the Perl script. What am I doing wrong? Note: the fix can only be in the Perl script. The Java app can't be changed. Also, File::Basename is there because I'm using it in the real script.

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• Retrieve KEYWORDS from META tag in a HTML WebPage using JAVA.

  - by kooldave98

  Hello all, I want to retrieve all the content words from a HTML WebPage and all the keywords contained in the META TAG of the same HTML webpage using Java. For example, consider this html source code: <html> <head> <meta name = "keywords" content = "deception, intricacy, treachery"> </head> <body> My very short html document. <br> It has just 2 'lines'. </body> </html> The CONTENT WORDS here are: my, very, short, html, document, it, has, just, lines Note: The punctuation and the number '2' are ruled out. The KEYWORDS here are: deception, intricacy, treachery I have created a class for this purpose called WebDoc, this is as far as I have been able to get. import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URL; import java.util.Set; import java.util.TreeSet; public class WebDoc { protected URL _url; protected Set<String> _contentWords; protected Set<String> _keyWords public WebDoc(URL paramURL) { _url = paramURL; } public Set<String> getContents() throws IOException { //URL url = new URL(url); Set<String> contentWords = new TreeSet<String>(); BufferedReader in = new BufferedReader(new InputStreamReader(_url.openStream())); String inputLine; while ((inputLine = in.readLine()) != null) { // Process each line. contentWords.add(RemoveTag(inputLine)); //System.out.println(RemoveTag(inputLine)); } in.close(); System.out.println(contentWords); _contentWords = contentWords; return contentWords; } public String RemoveTag(String html) { html = html.replaceAll("\\<.*?>",""); html = html.replaceAll("&",""); return html; } public Set<String> getKeywords() { //NO IDEA ! return null; } public URL getURL() { return _url; } @Override public String toString() { return null; } }

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• The battle between Java vs. C#

  The battle between Java vs. C# has been a big debate amongst the development community over the last few years. Both languages have specific pros and cons based on the needs of a particular project. In general both languages utilize a similar coding syntax that is based on C++, and offer developers similar functionality. This being said, the communities supporting each of these languages are very different. The divide amongst the communities is much like the political divide in America, where the Java community would represent the Democrats and the .Net community would represent the Republicans. The Democratic Party is a proponent of the working class and the general population. Currently, Java is deeply entrenched in the open source community that is distributed freely to anyone who has an interest in using it. Open source communities rely on developers to keep it alive by constantly contributing code to make applications better; essentially they develop code by the community. This is in stark contrast to the C# community that is typically a pay to play community meaning that you must pay for code that you want to use because it is developed as products to be marketed and sold for a profit. This ties back into my reference to the Republicans because they typically represent the needs of business and personal responsibility. This is emphasized by the belief that code is a commodity and that it can be sold for a profit which is in direct conflict to the laissez-faire beliefs of the open source community. Beyond the general differences between Java and C#, they also target two different environments. Java is developed to be environment independent and only requires that users have a Java virtual machine running in order for the java code to execute. C# on the other hand typically targets any system running a windows operating system and has the appropriate version of the .Net Framework installed. However, recently there has been push by a segment of the Open source community based around the Mono project that lets C# code run on other non-windows operating systems. In addition, another feature of C# is that it compiles into an intermediate language, and this is what is executed when the program runs. Because C# is reduced down to an intermediate language called Common Language Runtime (CLR) it can be combined with other languages that are also compiled in to the CLR like Visual Basic (VB) .Net, and F#. The allowance and interaction between multiple languages in the .Net Framework enables projects to utilize existing code bases regardless of the actual syntax because they can be compiled in to CLR and executed as one codebase. As a software engineer I personally feel that it is really important to learn as many languages as you can or at least be open to learn as many languages as you can because no one language will work in every situation.  In some cases Java may be a better choice for a project and others may be C#. It really depends on the requirements of a project and the time constraints. In addition, I feel that is really important to concentrate on understanding the logic of programming and be able to translate business requirements into technical requirements. If you can understand both programming logic and business requirements then deciding which language to use is just basically choosing what syntax to write for a given business problem or need. In regards to code refactoring and dynamic languages it really does not matter. Eventually all projects will be refactored or decommissioned to allow for progress. This is the way of life in the software development industry. The language of a project should not be chosen based on the fact that a project will eventually be refactored because they all will get refactored.

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• Java: how to avoid circual references when dumping object information with reflection?

  - by Tom

  I've modified an object dumping method to avoid circual references causing a StackOverflow error. This is what I ended up with: //returns all fields of the given object in a string public static String dumpFields(Object o, int callCount, ArrayList excludeList) { //add this object to the exclude list to avoid circual references in the future if (excludeList == null) excludeList = new ArrayList(); excludeList.add(o); callCount++; StringBuffer tabs = new StringBuffer(); for (int k = 0; k < callCount; k++) { tabs.append("\t"); } StringBuffer buffer = new StringBuffer(); Class oClass = o.getClass(); if (oClass.isArray()) { buffer.append("\n"); buffer.append(tabs.toString()); buffer.append("["); for (int i = 0; i < Array.getLength(o); i++) { if (i < 0) buffer.append(","); Object value = Array.get(o, i); if (value != null) { if (excludeList.contains(value)) { buffer.append("circular reference"); } else if (value.getClass().isPrimitive() || value.getClass() == java.lang.Long.class || value.getClass() == java.lang.String.class || value.getClass() == java.lang.Integer.class || value.getClass() == java.lang.Boolean.class) { buffer.append(value); } else { buffer.append(dumpFields(value, callCount, excludeList)); } } } buffer.append(tabs.toString()); buffer.append("]\n"); } else { buffer.append("\n"); buffer.append(tabs.toString()); buffer.append("{\n"); while (oClass != null) { Field[] fields = oClass.getDeclaredFields(); for (int i = 0; i < fields.length; i++) { if (fields[i] == null) continue; buffer.append(tabs.toString()); fields[i].setAccessible(true); buffer.append(fields[i].getName()); buffer.append("="); try { Object value = fields[i].get(o); if (value != null) { if (excludeList.contains(value)) { buffer.append("circular reference"); } else if ((value.getClass().isPrimitive()) || (value.getClass() == java.lang.Long.class) || (value.getClass() == java.lang.String.class) || (value.getClass() == java.lang.Integer.class) || (value.getClass() == java.lang.Boolean.class)) { buffer.append(value); } else { buffer.append(dumpFields(value, callCount, excludeList)); } } } catch (IllegalAccessException e) { System.out.println("IllegalAccessException: " + e.getMessage()); } buffer.append("\n"); } oClass = oClass.getSuperclass(); } buffer.append(tabs.toString()); buffer.append("}\n"); } return buffer.toString(); } The method is initially called like this: System.out.println(dumpFields(obj, 0, null); So, basically I added an excludeList which contains all the previousely checked objects. Now, if an object contains another object and that object links back to the original object, it should not follow that object further down the chain. However, my logic seems to have a flaw as I still get stuck in an infinite loop. Does anyone know why this is happening?

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• SQL SERVER – Developer Training Resources and Summary Roundup

  - by pinaldave

  It is always pleasure for any author when other renowned authors in the industry write about you. Earlier I wrote a five part blog series on Developer Training and I have received a phenomenal response to the series. I have received plenty of comments, questions and feedback. I thought it would be nice to sum up the whole series as well answer a few of the questions received. Quick Recap Developer Training - Importance and Significance - Part 1 In this part we discussed the importance of training in the real world. The most important and valuable resource any company is its employee. Employees who have been well-trained will be better at their jobs and produce a better product.  An employee who is well trained obviously knows more about their job and all the technical aspects. I have a very high opinion about training employees and it is the most important task. Developer Training – Employee Morals and Ethics – Part 2 In this part we discussed the most crucial components of training. Often employees are expecting the company to pay for their training and the company expresses no interest in training the employee. Quite often training expenses are the real issue for both the employee and employer. There are companies that pay for 100% of the expenses and there are employees who opt for training on their own expense during their personal time. Training is often looked at as vacation by employee and employers and we need to change this mind-set. One of the ways is to report back the learning to your manager and implement newly learned knowledge in day-to-day work. Developer Training – Difficult Questions and Alternative Perspective - Part 3 This part was the most difficult to write as I tried to address a few difficult questions and answers. Training is such a sensitive issue that many developers when not receiving chance for training think about leaving the organization. The manager often feels pressure to accommodate every single employee for training even though his training budget is limited. It is indeed the responsibility of the developer to get maximum advantage from the training. Training immediately helps organizations but stays as a part of an employee’s knowledge forever. Developer Training – Various Options for Developer Training – Part 4 In this part I tried to explore a few methods and options for training. The generic feedback I received on this blog post was short and I should have explored each of the subject of the training in details. I believe there are two big buckets of training 1) Instructor Lead Training and 2) Self Lead Training. The common element between both the methods is “learning material”. Learning material can be of any format – videos, books, paper notes or just a plain black board. Instructor-led training is a very effective mode but not possible every single time. During the course of the developer’s career, one has to learn lots of new technology and it is almost impossible to have a quality trainer available on that subject at that time. Books are most effective and proven methods, however, it always helps if someone explains the concepts of the book with a demonstration. In recent times I have started to believe in online trainings which leads to a hybrid experience. Online trainings take the best part of the books and the best part of the instructor-led training and gives effective training in a matter of hours. Developer Training – A Conclusive Summary- Part 5 In this part, I shared what I was continuously thinking about developer training. There is no better teacher than oneself. There is no better motivation than a personal desire to learn new technology. Honestly there is nothing more personal learning. That “change is the only constant” and “adapt & overcome” are the essential lessons of life. One cannot stop the learning and resist the change. In the IT industry “ego of knowing all” and the “resistance to change” are the most challenging issues. Once someone overcomes them, life is much easier. I believe that proper and appropriate high quality training can help to address the burning issues. Opinion of Friends I invited a few of my friends to express their opinion about developer training and here are their opinions. I am listing them here in the order of the blog post publishing date. Nakul Vachhrajani - Developer Trainings-Importance, Benefits, Tips and follow-up Nakul’s sums of many of the concepts which are complementary to my blog posts. Nakul addresses the burning question of developer training with different angles. I am personally very impressed by his following statement - “Being skilled does not mean having just a stack of certifications, but it also means having an understanding about the internals of the products that you are working on – and using that knowledge to improve the efficiency & productivity at the workplace in turn resulting in better products, better consulting abilities and a happier self.” Nakul also suggests the online training options of Pluralsight. Vinod Kumar - Training–a necessity or bonus Vinod Kumar comes up with excellent follow up on developer training. Vinod is known for his inspirational writing about SQL Server. Vinod starts with a story of a student who is extremely eager to learn the wisdom of life from a monk but the monk does not accept him as a disciple for a long time. The conversation between student and monk is indeed an essence of all learning. We all want to learn quickly and be successful but the most important thing in life is to have the right attitude towards learning and more so towards life. The blog post end with a very important thought about how to avoid the famous excuse – “I don’t have enough time.” Ritesh Shah - Training – useful or useless? Ritesh brings up very important concept related to training. Ritesh in his meticulous style explains why training is an important and lifelong process. Training must not stop at any age but should continue forever. The moment training stops, progress stops along with. Paras Doshi - Professional Development Resource Paras is known for his to–the-point writing, and has summarized the five part series very precisely. He read the five part series and created a digest summary of the blog post. If you are in a rush and have no time to read my five series – I suggest you read his blog post. Training Resources I am often asked what the best resources for learning new technology are. This is the most difficult question EVER. There are plenty of good training resources available. When it is about training our needs are different, our preference of learning is different and we all have an opinion. Additionally, we all are located in different geographic locations worldwide and there is no way one solution will fit all. However, let me list a few of the training resources which I have built so far and you can consume them if you find it relevant to your need. SQL Server Books SQL Server Interview Questions and Answers SQL Wait Stats SQL Programming Joes 2 Pros SQL Server Video Tutorials SQL Server Questions and Answers SQL Server Performance: Indexing Basics SQL Server Performance: Introduction to Query Tuning SQL in Sixty Seconds Series of Sixty Seconds Learning Video on YouTube Trust me worldwide web is very big and there are plenty of high quality learning materials available worldwide – trainer-led as well online. I suggest you explore various options and make the best choice for yourself. Remember, training is your personal journey and it should never stop. Are you ready? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Developer Training, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Weekly Series – Memory Lane – #051

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Explanation and Understanding NOT NULL Constraint NOT NULL is integrity CONSTRAINT. It does not allow creating of the row where column contains NULL value. Most discussed questions about NULL is what is NULL? I will not go in depth analysis it. Simply put NULL is unknown or missing data. When NULL is present in database columns, it can affect the integrity of the database. I really do not prefer NULL in the database unless they are absolutely necessary. Three T-SQL Script to Create Primary Keys on Table I have always enjoyed writing about three topics Constraint and Keys, Backup and Restore and Datetime Functions. Primary Keys constraints prevent duplicate values for columns and provides a unique identifier to each column, as well it creates clustered index on the columns. 2008 Get Numeric Value From Alpha Numeric String – UDF for Get Numeric Numbers Only SQL is great with String operations. Many times, I use T-SQL to do my string operation. Let us see User Defined Function, which I wrote a few days ago, which will return only Numeric values from Alpha Numeric values. Introduction and Example of UNION and UNION ALL It is very much interesting when I get requests from blog reader to re-write my previous articles. I have received few requests to rewrite my article SQL SERVER – Union vs. Union All – Which is better for performance? with examples. I request you to read my previous article first to understand what is the concept and read this article to understand the same concept with an example. Downgrade Database for Previous Version The main questions is how they can downgrade the from SQL Server 2005 to SQL Server 2000? The answer is : Not Possible. Get Common Records From Two Tables Without Using Join Following is my scenario, Suppose Table 1 and Table 2 has same column e.g. Column1 Following is the query, 1. Select column1,column2 From Table1 2. Select column1 From Table2 I want to find common records from these tables, but I don’t want to use the Join clause because for that I need to specify the column name for Join condition. Will you help me to get common records without using Join condition? I am using SQL Server 2005. Retrieve – Select Only Date Part From DateTime – Best Practice – Part 2 A year ago I wrote a post about SQL SERVER – Retrieve – Select Only Date Part From DateTime – Best Practice where I have discussed two different methods of getting the date part from datetime. Introduction to CLR – Simple Example of CLR Stored Procedure CLR is an abbreviation of Common Language Runtime. In SQL Server 2005 and later version of it database objects can be created which are created in CLR. Stored Procedures, Functions, Triggers can be coded in CLR. CLR is faster than T-SQL in many cases. CLR is mainly used to accomplish tasks which are not possible by T-SQL or can use lots of resources. The CLR can be usually implemented where there is an intense string operation, thread management or iteration methods which can be complicated for T-SQL. Implementing CLR provides more security to the Extended Stored Procedure. 2009 Comic Slow Query – SQL Joke Before Presentation After Presentation Enable Automatic Statistic Update on Database In one of the recent projects, I found out that despite putting good indexes and optimizing the query, I could not achieve an optimized performance and I still received an unoptimized response from the SQL Server. On examination, I figured out that the culprit was statistics. The database that I was trying to optimize had auto update of the statistics was disabled. Recently Executed T-SQL Query Please refer to blog post  query to recently executed T-SQL query on database. Change Collation of Database Column – T-SQL Script – Consolidating Collations – Extention Script At some time in your DBA career, you may find yourself in a position when you sit back and realize that your database collations have somehow run amuck, or are faced with the ever annoying CANNOT RESOLVE COLLATION message when trying to join data of varying collation settings. 2010 Visiting Alma Mater – Delivering Session on Database Performance and Career – Nirma Institute of Technology Everyone always dreams of visiting their school and college, where they have studied once. It is a great feeling to see the college once again – where you have spent the wonderful golden years of your time. College time is filled with studies, education, emotions and several plans to build a future. I consider myself fortunate as I got the opportunity to study at some of the best places in the world. Change Column DataTypes There are times when I feel like writing that I am a day older in SQL Server. In fact, there are many who are looking for a solution that is simple enough. Have you ever searched online for something very simple. I often do and enjoy doing things which are straight forward and easy to change. 2011 Three DMVs – sys.dm_server_memory_dumps – sys.dm_server_services – sys.dm_server_registry In this blog post we will see three new DMVs which are introduced in Denali. The DMVs are very simple and there is not much to describe them. So here is the simple game. I will be asking a question back to you after seeing the result of the each of the DMV and you help me to complete this blog post. A Simple Quiz – T-SQL Brain Trick If you have some time, I strongly suggest you try this quiz out as it is for sure twists your brain. 2012 List All The Column With Specific Data Types in Database 5 years ago I wrote script SQL SERVER – 2005 – List All The Column With Specific Data Types, when I read it again, it is very much relevant and I liked it. This is one of the script which every developer would like to keep it handy. I have upgraded the script bit more. I have included few additional information which I believe I should have added from the beginning. It is difficult to visualize the final script when we are writing it first time. Find First Non-Numeric Character from String The function PATINDEX exists for quite a long time in SQL Server but I hardly see it being used. Well, at least I use it and I am comfortable using it. Here is a simple script which I use when I have to identify first non-numeric character. Finding Different ColumnName From Almost Identitical Tables Well here is the interesting example of how we can use sys.column catalogue views and get the details of the newly added column. I have previously written about EXCEPT over here which is very similar to MINUS of Oracle. Storing Data and Files in Cloud – Dropbox – Personal Technology Tip I thought long and hard about doing a Personal Technology Tips series for this blog.  I have so many tips I’d like to share.  I am on my computer almost all day, every day, so I have a treasure trove of interesting tidbits I like to share if given the chance.  The only thing holding me back – which tip to share first?  The first tip obviously has the weight of seeming like the most important.  But this would mean choosing amongst my favorite tricks and shortcuts.  This is a hard task. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• org.apache.sling.scripting.jsp.jasper.JasperException: Unable to load tag handler class [migrated]

  - by Babak Behzadi

  I'm developing an Apache Sling WCMS and using java tag libs to rendering some data. I defined a jsp tag lib with following descriptor and handler class: TLD file contains: <?xml version="1.0" encoding="UTF-8"?> <taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"> <tlib-version>1.0</tlib-version> <short-name>taglibdescriptor</short-name> <uri>http://bob/taglibs</uri> <tag> <name>testTag</name> <body-content>tagdependent</body-content> <tag-class>org.bob.taglibs.test.TestTagHandler</tag-class> </tag> </taglib> Tag handler class: package org.bob.taglibs.test; import javax.servlet.jsp.tagext.TagSupport; public class TestTagHandler extends TagSupport{ @Override public int doStartTag(){ try { pageContext.getOut().print("<h1>Helloooooooo</h1>"); } catch(Exception e) { return SKIP_BODY; } return EVAL_BODY_INCLUDE; } } I packaged the tag lib as BobTagLib.jar and deployed it as a bundle using Sling Web Console. I used this tag lib in a jsp page deployed in my Sling repository: index.jsp: <%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib prefix="bob" uri="http://bob/taglibs" %> <html> <head><title>Simple jsp page</title></head> <body> <bob:testTag/> </body> </html> Calling the page cause the following exception: org.apache.sling.scripting.jsp.jasper.JasperException: /apps/TagTest/index.jsp(7,5) Unable to load tag handler class "org.bob.taglibs.test.TestTagHandler" for tag "bob:testTag" ... Can any one get me a solution? In advance, any help is apreciated.

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• What modern design pattern / software engineering books for Java SE 6 do you recommend ?

  - by Scott Davies

  Hi, I am very familiar with Java 6 SE language features and am now looking for modern books that cover design patterns in Java for beginners as well as software engineering books that discuss architectures, algorithms and best practices in Java coding (sort of like the Effective C# books). I am aware of the classic GoF design patterns book, however, I'd like a more modern reference that takes advantage of the features of Java 6 SE. What books would you recommend ? Thanks, Scott

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• How much freedom should a programmer have in choosing a language and framework?

  - by Spencer

  I started working at a company that is primarily a C# oriented. We have a few people who like Java and JRuby, but a majority of programmers here like C#. I was hired because I have a lot of experience building web applications and because I lean towards newer technologies like JRuby on Rails or nodejs. I have recently started on a project building a web application with a focus on getting a lot of stuff done in a short amount of time. The software lead has dictated that I use mvc4 instead of rails. That might be OK, except I don't know mvc4, I don't know C# and I am the only one responsible for creating the web application server and front-end UI. Wouldn't it make sense to use a framework that I already know extremely well (Rails) instead of using mvc4? The two reasons behind the decision was that the tech lead doesn't know Jruby/rails and there would be no way to reuse the code. Counter arguments: He won't be contributing to the code and is frankly, not needed on this project. So, it doesn't really matter if he knows JRuby/rails or not. We actually can reuse the code since we have a lot of java apps that JRuby can pull code from and vice-versa. In fact, he has dedicated some resources to convert a Java library to C#, instead of just running the Java library on the JRuby on Rails app. All because he doesn't like Java or JRuby I have built many web applications, but using something unfamiliar is causing some spin-up and I am unable to build an awesome application in as short of a time that I'm used to. This would be fine, learning new technologies is important in this field. The problem is, for this project, we need to get a lot done in a short period of time. At what point should a developer be allowed to choose his tools? Is this dependent on the company? Does my company suck or is this considered normal? Do greener pastures exist? Am I looking at this the wrong way? Bonus: Should I just keep my head down and move along at a snails pace, or defy orders and go with what I know in order to make this project more successful? Edit: I had actually created a fully function rails application (on my own time) and showed it to the team and it did not seem to matter. I am currently porting it to mvc4 (slowly).

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• Session Report - Java on the Raspberry Pi

  - by Janice J. Heiss

  On mid-day Wednesday, the always colorful Oracle Evangelist Simon Ritter demonstrated Java on the Raspberry Pi at his session, “Do You Like Coffee with Your Dessert?”. The Raspberry Pi consists of a credit card-sized single-board computer developed in the UK with the intention of stimulating the teaching of basic computer science in schools. “I don't think there is a single feature that makes the Raspberry Pi significant,” observed Ritter, “but a combination of things really makes it stand out. First, it's $35 for what is effectively a completely usable computer. You do have to add a power supply, SD card for storage and maybe a screen, keyboard and mouse, but this is still way cheaper than a typical PC. The choice of an ARM (Advanced RISC Machine and Acorn RISC Machine) processor is noteworthy, because it avoids problems like cooling (no heat sink or fan) and can use a USB power brick. When you add in the enormous community support, it offers a great platform for teaching everyone about computing.”Some 200 enthusiastic attendees were present at the session which had the feel of Simon Ritter sharing a fun toy with friends. The main point of the session was to show what Oracle was doing to support Java on the Raspberry Pi in a way that is entertaining and fun. Ritter pointed out that, in addition to being great for teaching, it’s an excellent introduction to the ARM architecture, and runs well with Java and will get better once it has official hard float support. The possibilities are vast.Ritter explained that the Raspberry Pi Project started in 2006 with the goal of devising a computer to inspire children; it drew inspiration from the BBC Micro literacy project of 1981 that produced a series of microcomputers created by the Acorn Computer company. It was officially launched on February 29, 2012, with a first production of 10,000 boards. There were 100,000 pre-orders in one day; currently about 4,000 boards are produced a day. Ritter described the specification as follows:* CPU: ARM 11 core running at 700MHz Broadcom SoC package Can now be overclocked to 1GHz (without breaking the warranty!) * Memory: 256Mb* I/O: HDMI and composite video 2 x USB ports (Model B only) Ethernet (Model B only) Header pins for GPIO, UART, SPI and I2C He took attendees through a brief history of ARM Architecture:* Acorn BBC Micro (6502 based) Not powerful enough for Acorn’s plans for a business computer * Berkeley RISC Project UNIX kernel only used 30% of instruction set of Motorola 68000 More registers, less instructions (Register windows) One chip architecture to come from this was… SPARC * Acorn RISC Machine (ARM) 32-bit data, 26-bit address space, 27 registers First machine was Acorn Archimedes * Spin off from Acorn, Advanced RISC MachinesNext he presented its features:* 32-bit RISC Architecture–  ARM accounts for 75% of embedded 32-bit CPUs today– 6.1 Billion chips sold last year (zero manufactured by ARM)* Abstract architecture and microprocessor core designs– Raspberry Pi is ARM11 using ARMv6 instruction set* Low power consumption– Good for mobile devices– Raspberry Pi can be powered from 700mA 5V only PSU– Raspberry Pi does not require heatsink or fanHe described the current ARM Technology:* ARMv6– ARM 11, ARM Cortex-M* ARMv7– ARM Cortex-A, ARM Cortex-M, ARM Cortex-R* ARMv8 (Announced)– Will support 64-bit data and addressingHe next gave the Java Specifics for ARM: Floating point operations* Despite being an ARMv6 processor it does include an FPU– FPU only became standard as of ARMv7* FPU (Hard Float, or HF) is much faster than a software library* Linux distros and Oracle JVM for ARM assume no HF on ARMv6– Need special build of both– Raspbian distro build now available– Oracle JVM is in the works, release date TBDNot So RISCPerformance Improvements* DSP Enhancements* Jazelle* Thumb / Thumb2 / ThumbEE* Floating Point (VFP)* NEON* Security Enhancements (TrustZone)He spent a few minutes going over the challenges of using Java on the Raspberry Pi and covered:* Sound* Vision * Serial (TTL UART)* USB* GPIOTo implement sound with Java he pointed out:* Sound drivers are now included in new distros* Java Sound API– Remember to add audio to user’s groups– Some bits work, others not so much* Playing (the right format) WAV file works* Using MIDI hangs trying to open a synthesizer* FreeTTS text-to-speech– Should work once sound works properlyHe turned to JavaFX on the Raspberry Pi:* Currently internal builds only– Will be released as technology preview soon* Work involves optimal implementation of Prism graphics engine– X11?* Once the JavaFX implementation is completed there will be little of concern to developers-- It’s just Java (WORA). He explained the basis of the Serial Port:* UART provides TTL level signals (3.3V)* RS-232 uses 12V signals* Use MAX3232 chip to convert* Use this for access to serial consoleHe summarized his key points. The Raspberry Pi is a very cool (and cheap) computer that is great for teaching, a great introduction to ARM that works very well with Java and will work better in the future. The opportunities are limitless. For further info, check out, Raspberry Pi User Guide by Eben Upton and Gareth Halfacree. From there, Ritter tried out several fun demos, some of which worked better than others, but all of which were greeted with considerable enthusiasm and support and good humor (even when he ran into some glitches).  All in all, this was a fun and lively session.

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• Merge sort. ArrayIndexOutOfBoundsException [migrated]

  - by user94892

  When I execute the program I am getting an error as stated below the program. Please help me figure out the problem.. import java.util.*; class Mergesort { public static void main(String args[]) { Scanner in= new Scanner(System.in); System.out.println("Enter the number of elements"); int n= in.nextInt(); int a[]= new int[n]; System.out.println("Enter the contents"); for(int i=0; i<n; i++) { a[i]=in.nextInt(); } a = mergesort(a,n); for(int i=0; i<n; i++) { System.out.println(a[i]); } } public static int[] mergesort(int[] x, int z) { if(z==1) { return x; } int b[]=new int[z/2]; int c[]=new int[z-z/2]; int i,j,k; for(int p=0;p<z/2; p++) { b[p]= x[p]; c[p]= x[p+z/2]; } c[z-z/2-1]= x[z-1]; b= mergesort(b,z/2); c= mergesort(c,z-z/2); for(i=0,j=0,k=0; k<z; k++) { if(b[i]<=c[j]) { x[k]=b[i]; i++; } else if( b[i]>c[j]) { x[k]=c[j]; j++; } else if(i== z/2) { x[k]= c[j]; j++; } else if(j == z-z/2) { x[k]= b[i]; i++; } } return x; } } Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1 at Mergesort.mergesort(Mergesort.java:41) at Mergesort.mergesort(Mergesort.java:36) at Mergesort.main(Mergesort.java:16)

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• Monitoring C++ applications

  - by Scott A

  We're implementing a new centralized monitoring solution (Zenoss). Incorporating servers, networking, and Java programs is straightforward with SNMP and JMX. The question, however, is what are the best practices for monitoring and managing custom C++ applications in large, heterogenous (Solaris x86, RHEL Linux, Windows) environments? Possibilities I see are: Net SNMP Advantages single, central daemon on each server well-known standard easy integration into monitoring solutions we run Net SNMP daemons on our servers already Disadvantages: complex implementation (MIBs, Net SNMP library) new technology to introduce for the C++ developers rsyslog Advantages single, central daemon on each server well-known standard unknown integration into monitoring solutions (I know they can do alerts based on text, but how well would it work for sending telemetry like memory usage, queue depths, thread capacity, etc) simple implementation Disadvantages: possible integration issues somewhat new technology for C++ developers possible porting issues if we switch monitoring vendors probably involves coming up with an ad-hoc communication protocol (or using RFC5424 structured data; I don't know if Zenoss supports that without custom Zenpack coding) Embedded JMX (embed a JVM and use JNI) Advantages consistent management interface for both Java and C++ well-known standard easy integration into monitoring solutions somewhat simple implementation (we already do this today for other purposes) Disadvantages: complexity (JNI, thunking layer between native C++ and Java, basically writing the management code twice) possible stability problems requires a JVM in each process, using considerably more memory JMX is new technology for C++ developers each process has it's own JMX port (we run a lot of processes on each machine) Local JMX daemon, processes connect to it Advantages single, central daemon on each server consistent management interface for both Java and C++ well-known standard easy integration into monitoring solutions Disadvantages: complexity (basically writing the management code twice) need to find or write such a daemon need a protocol between the JMX daemon and the C++ process JMX is new technology for C++ developers CodeMesh JunC++ion Advantages consistent management interface for both Java and C++ well-known standard easy integration into monitoring solutions single, central daemon on each server when run in shared JVM mode somewhat simple implementation (requires code generation) Disadvantages: complexity (code generation, requires a GUI and several rounds of tweaking to produce the proxied code) possible JNI stability problems requires a JVM in each process, using considerably more memory (in embedded mode) Does not support Solaris x86 (deal breaker) Even if it did support Solaris x86, there are possible compiler compatibility issues (we use an odd combination of STLPort and Forte on Solaris each process has it's own JMX port when run in embedded mode (we run a lot of processes on each machine) possibly precludes a shared JMX server for non-C++ processes (?) Is there some reasonably standardized, simple solution I'm missing? Given no other reasonable solutions, which of these solutions is typically used for custom C++ programs? My gut feel is that Net SNMP is how people do this, but I'd like other's input and experience before I make a decision.

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• Deploying web services on a RHEL 5 box using Apache/Tomcat/Axis/Java.

  - by Deepak Konidena

  Hi, I am new to the Web services scene. I currently have access to a RHEL5 box and i need to deploy a java web service on it. It runs apache and i know this because i have a website hosted on this machine. Now, i want to deploy a web service on to this website to be able to just pass a link to someone when they need to access my web service. Could someone point out a resource or explain what all i need to get the webservice deployed using Tomcat/Apache Axis and Java. I have done this on Windows (hosted on localhost) but couldn't quite figure out things on linux. Any help is greatly appreciated. Thanks. Deepak.

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• 3½" PATA Western Digital Caviar SE (250MB) makes steady ticking sound when idle

  - by intuited

  I've started to notice a ticking sound emanating from my WD2500JB. It is not alarmingly loud. The sound seems to occur only when the drive has been idle for some time, and will cease upon (some?) disk activity. The sound has a regular, steady cadence of somewhere between about 4 and 6 ticks per second. I'm not entirely certain that it just started making these sounds, since I previously had the drive — mounted in a USB enclosure — stored out of earshot, and only recently moved it to where I can hear it. The SMART attributes for the drive do not indicate any problems. I did have some errors to clean up recently (since I started noticing the sounds). The errors occurred on an ext3 filesystem. The drive had been powered down while mounted a few times prior to that fsck. Is this cause for alarm? Should I scrap the drive on principle?

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• super slow WINDOWS 7 installation on asus p5q se plus

  - by dasko

  am i missing something obvious in the bios as this is not normal at all.

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• Cannot install any Feature/Role on Win2K R2 SE

  - by Parsa

  I was trying to install Exchange 2010 prerequisites, when I encountered some error. All look like the same. Like this one: Error: Installation of [Windows Process Activation Service] Configuration APIs failed. the server needs to be restarted to undo the changes. My server is running Windows Server 2008 R2 Standard Edition.

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• How do you keep Flash, Quicktime, Java etc up to date for your non-admin users?

  - by Scott

  How do you keep Flash, Quicktime, Java etc up to date for your non-admin users? Thanks

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• Where can I download a full .pdf copy of the Cisco Internetworking Technology Handbook, rather than

  - by flesh

  Cisco publish the Internetworking Technology Handbook on their website but they only provide the individual chapters in pdf. Is there a .pdf of the entire thing available?

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