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  • Rtsp Live Stream Android

    - by Filiz Gökçe
    I try to make live stream on android, I try lots of ways, but none of them doesnt work. Could you help me ? This is example of rtsp; mMediaPlayer = new MediaPlayer(); mMediaPlayer.setDataSource(KralStream.getTvStreamUrl().toString()); mMediaPlayer.setDisplay(holder); mMediaPlayer.prepareAsync(); mMediaPlayer.setOnBufferingUpdateListener(this); mMediaPlayer.setOnCompletionListener(this); mMediaPlayer.setOnPreparedListener(this); mMediaPlayer.setOnVideoSizeChangedListener(this); mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mMediaPlayer.setLooping(true); Exeption :05-26 10:22:46.186: ERROR/MediaPlayerService(10157): create PVPlayer 05-26 10:23:06.382: ERROR/PlayerDriver(10157): Command PLAYER_INIT completed with an error or info -1 05-26 10:23:06.382: ERROR/MediaPlayer(23800): error (1, -1) 05-26 10:23:06.382: ERROR/MediaPlayer(23800): Error (1,-1) rtsp; VideoView videoView=(VideoView)findViewById(R.id.videoView1); Uri uri = Uri.parse("rtsp://strm-3.tr.medianova.tv/rkraltv/rkraltv"); videoView.setVideoURI(uri); videoView.start(); Gives message;"Sorry, this video connot ve played." Exeptions;05-26 10:40:08.979: ERROR/MediaPlayerService(10157): create PVPlayer 05-26 10:40:09.188: INFO/ActivityManager(10163): Displayed activity com.giantrabbit.nagare/.KralTvNow: 433 ms (total 433 ms) 05-26 10:40:11.702: WARN/PowerManagerService(10163): Timer 0x3-0x3|0x1 05-26 10:40:29.061: WARN/MediaPlayer(24284): info/warning (1, 26) 05-26 10:40:29.061: INFO/MediaPlayer(24284): Info (1,26) 05-26 10:40:29.100: ERROR/PlayerDriver(10157): Command PLAYER_INIT completed with an error or info -1 05-26 10:40:29.104: ERROR/MediaPlayer(24284): error (1, -1) 05-26 10:40:29.108: ERROR/MediaPlayer(24284): Error (1,-1) rtsp; mPreview = (SurfaceView) findViewById(R.id.surface); holder = mPreview.getHolder(); holder.addCallback(this); holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); extras = getIntent().getExtras(); public void play() { try { Uri video = KralStream.getTvStreamUrl(); Toast.makeText(this, video.toString(), Toast.LENGTH_SHORT).show(); mMediaPlayer = new MediaPlayer(); mMediaPlayer.setDataSource(path); mMediaPlayer.setDisplay(holder); mMediaPlayer.prepare(); mMediaPlayer.setOnBufferingUpdateListener(this); mMediaPlayer.setOnCompletionListener(this); mMediaPlayer.setOnPreparedListener(this); mMediaPlayer.setOnVideoSizeChangedListener(this); mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); } catch (Exception e) { Log.e(TAG, "error: " + e.getMessage(), e); } } Exeption ; 05-26 10:36:57.589: ERROR/MediaPlayerService(10157): create PVPlayer 05-26 10:37:20.542: ERROR/PlayerDriver(10157): Command PLAYER_INIT completed with an error or info -1 05-26 10:37:20.542: ERROR/MediaPlayer(24240): error (1, -1) 05-26 10:37:20.565: WARN/PlayerDriver(10157): PVMFInfoErrorHandlingComplete 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): error: Prepare failed.: status=0x1 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): java.io.IOException: Prepare failed.: status=0x1 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.media.MediaPlayer.prepare(Native Method) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at com.giantrabbit.nagare.KralTvNow.play(KralTvNow.java:162) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at com.giantrabbit.nagare.KralTvNow.surfaceCreated(KralTvNow.java:215) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.SurfaceView.updateWindow(SurfaceView.java:536) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.SurfaceView.dispatchDraw(SurfaceView.java:339) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewGroup.drawChild(ViewGroup.java:1638) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewGroup.drawChild(ViewGroup.java:1638) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.View.draw(View.java:6796) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.widget.FrameLayout.draw(FrameLayout.java:352) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewGroup.drawChild(ViewGroup.java:1640) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.View.draw(View.java:6796) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.widget.FrameLayout.draw(FrameLayout.java:352) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1894) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewRoot.draw(ViewRoot.java:1407) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewRoot.performTraversals(ViewRoot.java:1163) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.os.Handler.dispatchMessage(Handler.java:99) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.os.Looper.loop(Looper.java:123) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at android.app.ActivityThread.main(ActivityThread.java:4627) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at java.lang.reflect.Method.invokeNative(Native Method) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at java.lang.reflect.Method.invoke(Method.java:521) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:871) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629) 05-26 10:37:20.682: ERROR/MediaPlayerDemo(24240): at dalvik.system.NativeStart.main(Native Method) 05-26 10:37:20.737: INFO/MediaPlayer(24240): Info (1,26) 05-26 10:37:20.737: ERROR/MediaPlayer(24240): Error (1,-1) 05-26 10:37:20.868: INFO/ActivityManager(10163): Displayed activity com.giantrabbit.nagare/.KralTvNow: 25864 ms (total 25864 ms) 05-26 10:37:23.777: WARN/PowerManagerService(10163): Timer 0x3-0x3|0x1 This is example of http ; mMediaPlayer = new MediaPlayer(); mMediaPlayer.setDataSource("http://ikral.garantisistem.com:1935/ikral/smil:kral.smil/playlist.m3u8"); mMediaPlayer.setDisplay(holder); mMediaPlayer.prepareAsync(); mMediaPlayer.setOnBufferingUpdateListener(this); mMediaPlayer.setOnCompletionListener(this); mMediaPlayer.setOnPreparedListener(this); mMediaPlayer.setOnVideoSizeChangedListener(this); mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mMediaPlayer.setLooping(true); Exeption: 05-26 10:16:24.276: ERROR/MediaPlayerService(10157): create PVPlayer 05-26 10:16:24.292: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferWriteDataStreamImpl 05-26 10:16:24.346: INFO/PlayerDriver(10157): buffering (100) 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.346: ERROR/(10157): IIIIIII Inside Constructor of PVMFMemoryBufferReadDataStreamImpl 05-26 10:16:24.350: WARN/MediaPlayer(23736): info/warning (1, 26) 05-26 10:16:24.354: ERROR/PlayerDriver(10157): Command PLAYER_INIT completed with an error or info -10 05-26 10:16:24.354: ERROR/MediaPlayer(23736): error (-10, -10) 05-26 10:16:24.354: WARN/PlayerDriver(10157): PVMFInfoErrorHandlingComplete 05-26 10:16:24.393: INFO/MediaPlayer(23736): Info (1,26) 05-26 10:16:24.393: ERROR/MediaPlayer(23736): Error (-10,-10) Htttp; VideoView videoView=(VideoView)findViewById(R.id.videoView1); Uri uri = Uri.parse("http://ikral.garantisistem.com:1935/ikral/smil:kral.smil/playlist.m3u8"); videoView.setVideoURI(uri); videoView.start(); Gives message;"Sorry, this video connot ve played." Filiz Gökçe

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  • Cordova polluted logs with persistent.js add()

    - by slaver113
    I am using the latest phonegap/cordova version 2.1. and my log in Eclipse logcat get polluted with code when i do var allItems = Item.all(); allItems.list(null, function (results) { results.forEach(function (r) { console.log(r.id+ " " + r.lat + " " + r.long + " " + r.state); }); }); I get a output like (for 100s of lines) 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } at :1149822901

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  • what's the right way to use scala.io.Source?

    - by woods
    In many examples, it is described that you can use scala.io.Source to read a whole file like this: val str = scala.io.Source.fromFile("test.txt").mkString() But closing the underlying stream is not mentioned. Why does Scala not provide a convenient way to do that such as with clause in Python? It looks useful but not difficult. Is there any other better way to do that safely in Scala, i means to read a whole file?

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  • How do I use continuations on Scala 2.8?

    - by Seth Tisue
    Scala 2.8.0.RC1 includes the continuations plugin on trunk for the first time, but the details of how to use it have changed from previous releases, so it's difficult to follow the blog entries and SO answers out there that talk about continuations but were written for previous versions.

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  • What's the new way to iterate over a Java Map in Scala 2.8.0?

    - by Alex R
    How does scala.collection.JavaConversions supercede the answers given here: http://stackoverflow.com/questions/495741/iterating-over-java-collections-in-scala (doesn't work because the "jcl" package is gone) and here http://www.eishay.com/2009/05/iterating-over-map-with-scala.html (doesn't work me in a complicated test which I'll try to boil down and post here later) The latter is actually a Scala Map question but I think I need to know both answers in order to iterate over a java.util.Map. Thanks

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  • Extending existing data structure in Scala.

    - by Lukasz Lew
    I have a normal tree defined in Scala. sealed abstract class Tree case class Node (...) extends Tree case class Leaf (...) extends Tree Now I want to add a member variable to all nodes and leaves in the tree. Is it possible with extend keyword or do I have to modify the tree classes by adding [T]?

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  • What is a "context bound" in Scala?

    - by Jesper
    One of the new features of Scala 2.8 are context bounds. What is a context bound and where is it useful? Of course I searched first (and found for example this) but I couldn't find any really clear and detailed information.

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  • How to get Ponter/Reference semantics in Scala.

    - by Lukasz Lew
    In C++ I would just take a pointer (or reference) to arr[idx]. In Scala I find myself creating this class to emulate a pointer semantic. class SetTo (val arr : Array[Double], val idx : Int) { def apply (d : Double) { arr(idx) = d } } Isn't there a simpler way? Doesn't Array class have a method to return some kind of reference to a particular field?

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  • Scala - learning by doing

    - by wrecked
    coming from the PHP-framework symfony (with Apache/MySQL) I would like to dive into the Scala programming language. I already followed a few tutorials and had a look at Lift and Play. Java isn't a stranger to me either. However the past showed that it's easiest to learn things by just doing them. Currently we have a little - mostly ajax-driven - application build on symfony at my company. My idea is to just build a little project similar to this one which might gets into production in the future. The app should feature: High scalability and performance a backend-server web-interface and a GUI-client There are plenty of questions arising when I think of this. First of all: Whats the best way to accomplish a easy to maintain, structured base for it? Would it be best to establish a socket based communication between pure-scala server/client and accessing that data via Lift or is building a Lift-app serving as a server and connecting the gui-client (via REST?) the better way? Furthermore I wounder which database to choose. I'm familiar with (My)SQL but feel like a fool beeing confronted with all these things like NoSQL, MongoDB and more. Thanks in advance!

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  • What is in scala-android.jar?

    - by synic
    I've been trying to experiment with developing Android applications with Scala. I've gotten to the point where I can get the app to compile, but there are no helper functions for things like: button.setOnClickListener( () => { text.setText("test") }) (I'm talking about the closure there) I see lots of references to scala-android.jar, and have this file in my project, but I'm not sure what it does, or how to use it. I get the feeling it has these helper conversion functions, but I'm not sure. Running jar -tvf scala-android.jar on the file gives me this: 401 Sun Jun 06 10:06:02 MDT 2010 scala/Function0$class.class 431 Sun Jun 06 10:06:02 MDT 2010 scala/Function0.class 572 Sun Jun 06 10:06:02 MDT 2010 scala/Function1.class 282 Sun Jun 06 10:06:02 MDT 2010 scala/ScalaObject$class.class 271 Sun Jun 06 10:06:02 MDT 2010 scala/ScalaObject.class 458 Sun Jun 06 10:06:02 MDT 2010 scala/runtime/BoxedUnit.class If this isn't what I'm looking for, is there a simple library that'll do conversions for this kind of stuff?

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  • Force close error expecting irregulary

    - by user1506019
    I have problem. I created an application which loads random layour from resources and I have problem because program shows random layout and closes , sometimes after 2 times and sometimes after a dozen, and I dont know where is a problem, I tried to run it on my phone and I added in the manifest write_external_storage permission, and still the same error.Please help me, and try to resolve this problem. here is my code in : java : package ka.ka.ka; import java.util.Random; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class KAMASActivity extends Activity implements OnClickListener { Button button1; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this); } @Override public void onClick(View v) { int min = 1; int max = 6; int i1=0; Random r = new Random(); i1 = r.nextInt(max - min + 1) + min; if(i1==1){setContentView(R.layout.image1); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==2){setContentView(R.layout.image2); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==3){setContentView(R.layout.image3); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==4){setContentView(R.layout.image4); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==5){setContentView(R.layout.image5); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==6){setContentView(R.layout.image6); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this); } } Android Manifest : <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="ka.ka.ka" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="7" /> <uses-permission android:name="android.permission.ACCESS_CHECKIN_PROPERTIES" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <application android:icon="@drawable/ikona" android:label="@string/app_name" > <activity android:name=".KAMASActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest> And he is logcat : 07-10 10:58:51.062: D/ddm-heap(218): Got feature list request 07-10 10:58:51.311: D/dalvikvm(218): GC freed 506 objects / 46032 bytes in 122ms 07-10 10:59:30.081: D/AndroidRuntime(218): Shutting down VM 07-10 10:59:30.081: W/dalvikvm(218): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 07-10 10:59:30.081: E/AndroidRuntime(218): Uncaught handler: thread main exiting due to uncaught exception 07-10 10:59:30.102: E/AndroidRuntime(218): java.lang.NullPointerException 07-10 10:59:30.102: E/AndroidRuntime(218): at ka.ka.ka.KAMASActivity.onClick(KAMASActivity.java:32) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.View.performClick(View.java:2364) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.View.onTouchEvent(View.java:4179) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.widget.TextView.onTouchEvent(TextView.java:6541) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.View.dispatchTouchEvent(View.java:3709) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 0 7-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow. java:1659) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.app.Activity.dispatchTouchEvent(Activity.java:2061) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewRoot.handleMessage(ViewRoot.java:1691) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.os.Handler.dispatchMessage(Handler.java:99) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.os.Looper.loop(Looper.java:123) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.app.ActivityThread.main(ActivityThread.java:4363) 07-10 10:59:30.102: E/AndroidRuntime(218): at java.lang.reflect.Method.invokeNative(Native Method) 07-10 10:59:30.102: E/AndroidRuntime(218): at java.lang.reflect.Method.invoke(Method.java:521) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 07-10 10:59:30.102: E/AndroidRuntime(218): at dalvik.system.NativeStart.main(Native Method) 07-10 10:59:30.121: I/dalvikvm(218): threadid=7: reacting to signal 3 07-10 10:59:30.121: E/dalvikvm(218): Unable to open stack trace file '/data/anr/traces.txt': Permission denied 07-10 10:59:32.562: I/Process(218): Sending signal. PID: 218 SIG: 9

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  • Diving into Scala with Cay Horstmann

    - by Janice J. Heiss
    A new interview with Java Champion Cay Horstmann, now up on otn/java, titled  "Diving into Scala: A Conversation with Java Champion Cay Horstmann," explores Horstmann's ideas about Scala as reflected in his much lauded new book,  Scala for the Impatient.  None other than Martin Odersky, the inventor of Scala, called it "a joy to read" and the "best introduction to Scala". Odersky was so enthused by the book that he asked Horstmann if the first section could be made available as a free download on the Typesafe Website, something Horstmann graciously assented to. Horstmann acknowledges that some aspects of Scala are very complex, but he encourages developers to simply stay away from those parts of the language. He points to several ways Java developers can benefit from Scala: "For example," he says, " you can write classes with less boilerplate, file and XML handling is more concise, and you can replace tedious loops over collections with more elegant constructs. Typically, programmers at this level report that they write about half the number of lines of code in Scala that they would in Java, and that's nothing to sneeze at. Another entry point can be if you want to use a Scala-based framework such as Akka or Play; you can use these with Java, but the Scala API is more enjoyable. " Horstmann observes that developers can do fine with Scala without grasping the theory behind it. He argues that most of us learn best through examples and not through trying to comprehend abstract theories. He also believes that Scala is the most attractive choice for developers who want to move beyond Java and C++.  When asked about other choices, he comments: "Clojure is pretty nice, but I found its Lisp syntax a bit off-putting, and it seems very focused on software transactional memory, which isn't all that useful to me. And it's not statically typed. I wanted to like Groovy, but it really bothers me that the semantics seems under-defined and in flux. And it's not statically typed. Yes, there is Groovy++, but that's in even sketchier shape. There are a couple of contenders such as Kotlin and Ceylon, but so far they aren't real. So, if you want to do work with a statically typed language on the JVM that exists today, Scala is simply the pragmatic choice. It's a good thing that it's such a nice choice." Learn more about Scala by going to the interview here.

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  • CodePlex Daily Summary for Monday, May 10, 2010

    CodePlex Daily Summary for Monday, May 10, 2010New ProjectsAzure Publish-Subscribe: Infrastructure implementing the publish-subscribe pattern in a Windows Azure context. The unit of publishing is an XML document with an optional l...Bakalarska prace SCSF: This work dealing with the technology of Microsoft Software Factories which makes possible an efficient development of applications under MS Windows.Begtostudy-Test: NoteExpress User Tool (NEUT) is a opensource project for NoteExpress user developpers to share their tools and ideas using secondary development. N...CodeReview: Code Review is an open source development tool based on the same approach than FxCop - check the compiled assemblies to enforce good practices rule...CommonFilter: CommonFilter is a subset of the CommonData project, containing just the functions and unit tests for filtering user input.Custom SharepointDesigner Actions: These are a couple of custom actions that i use in sharepoint designer to ease workflow creation.Customer Portal Accelerator for Microsoft Dynamics CRM: The Customer Portal accelerator for Microsoft Dynamics CRM provides businesses the ability to deliver portal capabilities to their customers while ...Danzica Asset Management System: Danzica is an asset management system written in C# that can ingest all of your hardware management systems into a single cohesive portal, giving y...Dot2Silverlight: Dot2Silverlight is a project thats enables to render graphs (written in Dot format) in Silverlight. dot2silverlight, dot, silverlight, C#, graphviz...eGrid_Windows7: This project will include a new platform independent version of the eGrid project. The new version will run on windows 7, using WPF 4 and the Surfa...Game project JAMK: game project on jamkHamcast for multi station coordination: Amateur Radio multiple station operation tends to have loggers and operators striving to get particular information from each other, like what IP a...Headspring Labs: Headspring Labs showcases presentations, samples, and starter kits developed by Headspring.Hongrui Software Development Management Platform: Hongrui Software Development Management Platform 鸿瑞软件开发管理平台(HrSDMP) LinkField: 带有链接的多列 Field migre.me plugin for Seesmic Desktop Platform: migre.me is a brazilian service created to reduces the size of URLs and provides tracking data for shortened links. migre.me plugin for Seesmic ...MISAO: MISAO is a presentation tool.Mongodb Management Studio: Mongodb Management Studio makes it easier for mongodb users (including DBA/Developers/Administrators) to use mongodb. It's developed in ASP.NET 4.0...MS Build for DotNetNuke module development: Automate the task of creating DotNetNuke module PA packs easily using MS Build. Create manifest files, include version #'s automatically and more.Rubyish: C# extensions providing a rubyish syntax to C#SharePoint 2007 Web Parts: The goal of this project is to develop a set of web parts for SharePoint 2007.SharePoint 2010 Web Parts: The goal of this project is to develop a set of web parts for SharePoint 2010.Taxomatic: Taxomatic adds the ability to bulk create Content Types and Columns to a SharePoint site collection. It also caters for the export of the Content T...trackuda: trackuda - track the motion!Web Camera Shooter: Small tool for taking screenshots from web camera and saving them to disk with few image filters as options.Windows API Code Pack Contrib: Extensions to Windows API Code PackNew ReleasesAlan Platform: Technical Preview 1: В центре данного релиза интерфейс, точнее не сам интерфейс, а принцип, по которому он построен. Используя парочку предоставленных свойств, можно со...Begtostudy-Test: Test: Don't Download.BFBC2 PRoCon: PRoCon 0.3.5.1: Release Notes ComingCBM-Command: 2010-05-09: Release Notes - 2010-05-09New Features FILE COPYING Changes Removed the Swap Panels functionality to make room for file copying. It's still in th...CBM-Command: 2010-05-10: Release Notes - 2010-05-10New Features Launching PRG Files New color schemes to better match the C128 and C64 platforms Function Keys Changes ...CommonFilter: CommonFilter0.3D: This initial release of CommonFilter 0.3D is a subset of the CommonData solution that contains just the filter functions.Custom SharepointDesigner Actions: Custom SPD Actions v1.0: This is the first version of the actions library, it includes: Calling a Webservice. Convert a string to a double. Convert a string to an integ...Customer Portal Accelerator for Microsoft Dynamics CRM: Customer Portal Accelerator for Dynamics CRM: The Customer Portal accelerator for Microsoft Dynamics CRM provides businesses the ability to deliver portal capabilities to their customers while ...EPiMVC - EPiServer CMS with ASP.NET MVC: EPiMVC CTP1: First release that mainly addresses routing. The release is described in greater detail here.Helium Frog Animator: Helium Frog 2_06SW3: This is a first release (not for end users as it is not packaged) of mods intended to make the program run easier on netbooks and customised for us...HouseFly controls: HouseFly controls alpha 0.9.8.0: HouseFly controls release 0.9.8.0 alphaID3Tag.Net: ID3TagLib.Net 1.1: The ID3Tag team is proud to release a new version of the ID3tag lib! New features: Removing of ID3V1 and ID3V2 tags Logging operations ( if enab...IT Tycoon: IT Tycoon 0.2.1: Switched to .NET Framework 4 and implemented some Parallel.ForEach calls.MeaMod Playme: MeaMod Playme 0.9.6.5 Bucking Bunny: MeaMod Playme 0.9.6.5 Bucking Bunny Version 0.9.6.5 | Change Set: 48050 -- Added Playme Store -- Added Buy Album -- Added OCDS/Core system -- Adde...migre.me plugin for Seesmic Desktop Platform: migre.me plugin 0.7.0.1: Initial release. Compatible with Seesmic Desktop Platform 0.7.0.772.MISAO: Ver. 5 Alpha(2010-05-10): Alpha versionMultiwfn: multiwfn1.3.2_source: multiwfn1.3.2_sourcePocket Wiki: Desktop Wiki (in dev): Full screen wiki for the PC - supports the same parsers that Pocket Wiki does. Currently in development but usable. Left side shows listbox of all ...Rubyish: alpha: intial buildSevenZipLib Library: v9.13 beta: New release to match 7-zip 9.13 betaShake - C# Make: Shake v0.1.11: Initial version of Shake's services (API), command line parameters (dynamic) now available via ShakeServices class. Introducing interfaces and bas...SharpNotes: SharpNotes (New): This is the release of SharpNotes.SharpNotes: SharpNotes Source (New): This is the source release of SharpNotes.StackOverflow Desktop Client in C# and WPF: StackOverflow Client 1.0: Improved UI Showing votes/answers/views on popups. Bug fixesTaxomatic: Design_0: Design documentThe Movie DB API: TMDB API v1.2: Updated to reflect changes in The Movie DB API.Web Camera Shooter: 1.0.0.0: Initial release. Unstable. Often exception AccessViolation from Touchless SDK.WF Personalplaner: Personalplaner v1.7.29.10127: - Drag und Drop wurde beim Plan und in der Maske unter Plan\Plan-Layout anpassen in die Grids eingefügt - Weitere kleine bugfixesWindows Phone 7 Panorama & Pivot controls: panorama + pivot controls v0.7 (samples included): Panorama and Pivot Controls source code + sample projects. - Phone.Controls.Samples : source code for the PanoramaControl and PivotControl. - Pic...XmlCodeEditor: Release 0.9 Alpha: Release 0.9 AlphaMost Popular ProjectsWBFS ManagerRawrAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)patterns & practices – Enterprise LibraryMicrosoft SQL Server Community & SamplesASP.NETPHPExcelMost Active Projectspatterns & practices – Enterprise LibraryRawrThe Information Literacy Education Learning Environment (ILE)Mirror Testing SystemCaliburn: An Application Framework for WPF and SilverlightjQuery Library for SharePoint Web Serviceswhitepatterns & practices - UnityTweetSharpBlogEngine.NET

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  • CodePlex Daily Summary for Thursday, June 06, 2013

    CodePlex Daily Summary for Thursday, June 06, 2013Popular ReleasesReliability Modeling and Prediction: Reliability Prediction v2.0.1: Including the reliability modeling schema and the reliability prediction tool. Including case studies (Reporting service and WebScan system). Check Readme.txt for a quick tutorial.Virtual Sport for Sport Team: Virtual Sport Website: This is the website to manage a sports team. Through this website you can manage the members of the team, from players to staff, schedules, and more. and for supporter, be able more easily get to know team through the this websiteChristoc's DotNetNuke Module Development Template: DotNetNuke 7 Project Templates V2.3 for VS2012: V2.3 - Release Date 6/5/2013 Items addressed in this 2.3 release Fixed bad namespace for BusinessController in one of the C# templates. Updated documentation in all templates. Setting up your DotNetNuke Module Development Environment Installing Christoc's DotNetNuke Module Development Templates Customizing the latest DotNetNuke Module Development Project TemplatesPulse: Pulse 0.6.7.0: A number of small bug fixes to stabilize the previous Beta. Sorry about the never ending "New Version" bug!ZXMAK2: Version 2.7.5.3: - debugger: add LPC indicator (last executed opcode pc) - add host joystick support (written by Eltaron) - change file extension for CMOS PENTEVO to "cmos" - add hardware value monitor (see Memory Map for PENTEVO/ATM/PROFI)QlikView Extension - Animated Scatter Chart: Animated Scatter Chart - v1.0: Version 1.0 including Source Code qar File Example QlikView application Tested With: Browser Firefox 20 (x64) Google Chrome 27 (x64) Internet Explorer 9 QlikView QlikView Desktop 11 - SR2 (x64) QlikView Desktop 11.2 - SR1 (x64) QlikView Ajax Client 11.2 - SR2 (based on x64)BarbaTunnel: BarbaTunnel 7.2: Warning: HTTP Tunnel is not compatible with version 6.x and prior, HTTP packet format has been changed. Check Version History for more information about this release.Harvester - Debug Viewer for Trace, NLog & Log4Net: v2.0.1 (.NET 4.0): Minor Updates Fixed incorrect process naming being displayed if process ID reassigned before cache invalidated. Fixed incorrect event type/source for TraceListener.TraceData methods. Updated NLog package references. Official Documentation Moved to GitHub http://cbaxter.github.com/Harvester Official Source Moved to GitHub https://github.com/cbaxter/HarvesterSuperWebSocket, a .NET WebSocket Server: SuperWebSocket 0.8: This release includes these changes below: Upgrade SuperSocket to 1.5.3 which is much more stable Added handshake request validating api (WebSocketServer.ValidateHandshake(TWebSocketSession session, string origin)) Fixed a bug that the m_Filters in the SubCommandBase can be null if the command's method LoadSubCommandFilters(IEnumerable<SubCommandFilterAttribute> globalFilters) is not invoked Fixed the compatibility issue on Origin getting in the different version protocols Marked ISub...BlackJumboDog: Ver5.9.0: 2013.06.04 Ver5.9.0 (1) ?????????????????????????????????($Remote.ini Tmp.ini) (2) ThreadBaseTest?? (3) ????POP3??????SMTP???????????????? (4) Web???????、?????????URL??????????????? (5) Ftp???????、LIST?????????????? (6) ?????????????????????Media Companion: Media Companion MC3.569b: New* Movies - Autoscrape/Batch Rescrape extra fanart and or extra thumbs. * Movies - Alternative editor can add manually actors. * TV - Batch Rescraper, AutoScrape extrafanart, if option enabled. Fixed* Movies - Slow performance switching to movie tab by adding option 'Disable "Not Matching Rename Pattern"' to Movie Preferences - General. * Movies - Fixed only actors with images were scraped and added to nfo * Movies - Fixed filter reset if selected tab was above Home Movies. * Updated Medi...Nearforums - ASP.NET MVC forum engine: Nearforums v9.0: Version 9.0 of Nearforums with great new features for users and developers: SQL Azure support Admin UI for Forum Categories Avoid html validation for certain roles Improve profile picture moderation and support Warn, suspend, and ban users Web administration of site settings Extensions support Visit the Roadmap for more details. Webdeploy package sha1 checksum: 9.0.0.0: e687ee0438cd2b1df1d3e95ecb9d66e7c538293b Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.93: Added -esc:BOOL switch (CodeSettings.AlwaysEscapeNonAscii property) to always force non-ASCII character (ch > 0x7f) to be escaped as the JavaScript \uXXXX sequence. This switch should be used if creating a Symbol Map and outputting the result to the a text encoding other than UTF-8 or UTF-16 (ASCII, for instance). Fixed a bug where a complex comma operation is the operand of a return statement, and it was looking at the wrong variable for possible optimization of = to just .Document.Editor: 2013.22: What's new for Document.Editor 2013.22: Improved Bullet List support Improved Number List support Minor Bug Fix's, improvements and speed upsPHPExcel: PHPExcel 1.7.9: See Change Log for details of the new features and bugfixes included in this release, and methods that are now deprecated.Droid Explorer: Droid Explorer 0.8.8.10 Beta: Fixed issue with some people having a folder called "android-4.2.2" in their build-tools path. - 16223 Magick.NET: Magick.NET 6.8.5.402: Magick.NET compiled against ImageMagick 6.8.5.4. These zip files are also available as a NuGet package: https://nuget.org/profiles/dlemstra/patterns & practices: Data Access Guidance: Data Access Guidance Drop3 2013.05.31: Drop 3DotNet.Highcharts: DotNet.Highcharts 2.0 with Examples: DotNet.Highcharts 2.0 Tested and adapted to the latest version of Highcharts 3.0.1 Added new chart types: Arearange, Areasplinerange, Columnrange, Gauge, Boxplot, Waterfall, Funnel and Bubble Added new type PercentageOrPixel which represents value of number or number with percentage. Used for sizes, width, height, length, etc. Removed inheritances in YAxis option classes. Closed issues: 682: Missing property - XAxisPlotLinesLabel.Text 688: backgroundColor and plotBackgroundColor are...DirectX Tool Kit: May 2013: May 30, 2013 Added more GeometricPrimitives: Cone, Tetrahedron, Octahedron, Dodecahedron, Icosahedron Updated to support loading new metadata from DDS files (if present) Fixed bug with loading of WIC 32bpp RGBE format images Fixed bug when skipping mipmaps in a 1D or 2D array texture DDS fileNew Projectsabang: ????????Alex Develop Kit: ????????C#?????????。AnaLog - Analyse Logique: Software for logical equations analyse. App Excess: App Platform for Windows.Associativy Frontend Engines Administration: Frontend Engines Administration module for the Associativy (http://associativy.com) Orchard graph platform.ATDD Applied (Example): Sample code for Nordic Testing Days 2013 workshop - Acceptance Test Driven Development Applied: An Intro to ATDD using Jasmine and SpecFlowAzCAD: AzCAD is a free CAD program.BVVD Project: SOURCE CODECrzy Engine: C# and XNA ORPG Game Development engine.Custom Pong: Custom PongEDID Puller: Simple C# application showing how to get the EDIDs of the connected monitors to a PC, in particular the manufacturer and model of the display device.GooMUI: A desktop player for the Google Play Music service that runs on Windows.Had: HadIIS Express GUI: The GUI for IISExpress (version 7.5 and 8.0) jean0605jabbrchangbranch: ddjQueryBuddy Port to .Net 4.0+: Upgrading the project to current dot net will make using this app easier for some folks!Kinopoly: Dieses Projekt ist eine Arbeit der Berufschule Bern, GIBB. Das Ziel ist es das berühmte Spiel Monopoly im Film Theme als eine Clientapplikation zu realisieren.Magic Engine - 2D and 3D engine developed by school students: Magic Engine - 2D and 3D engine developed by school studentsMetrics calculation: Calculates metrics with the use of Driven Metrics.Metro WPF: Metro WPF provides a set of controls and styles for you to build your metro style WPF applications.mysitie: this is unknown error site Native API Test Command-Line Utility: A command-line utility that allows the user to call native API function interactively and experiment with how they function.prakark06052013Hg01: *bold* _italics_ +underline+ ! Heading 1 !! Heading 2 * Bullet List ** Bullet List 2 # Number List ## Number List 2 [another wiki page] [url:http://www.example.prakark06052013Tfs01: *bold* _italics_ +underline+ ! Heading 1 !! Heading 2 * Bullet List ** Bullet List 2 # Number List ## Number List 2 [another wiki page] [url:http://www.example.prakarkGit06052013Git01: *bold* _italics_ +underline+ ! Heading 1 !! Heading 2 * Bullet List ** Bullet List 2 # Number List ## Number List 2 [url:http://www.example.com] {"Do QlikView Extension - Animated Scatter Chart: Animated scatter chart for QlikView, inspired by D3js.orgREADPDB(Program Database Reader): This tool uses the Microsoft Debug Interface Access Software Development Kit (DIA SDK) to parser PDB file SelfProject: Just For TestSlWfDesign: 11212SSZZ: SSZZ is a tool for Data Analysistest project codeplex: This is a testtesttom06052013git01: dfdstesttom06052013hg01: *bold* _italics_ +underline+ ! Heading 1 !! Heading 2 * Bullet List ** Bullet List 2 # Number List ## Number List 2 [another wiki page] [url:http://www.example.testtom06052013tfs01: gfdgfdthree: It's a personal project.Validation Rules Framework for C++: C++ framework for rule creation, validation and management.

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  • Question on Scala Closure (From "Programming in Scala")

    - by Ekkmanz
    I don't understand why authors said that Code Listing 9.1 from "Programming in Scala" use closure. In chapter 9, they show how to refactor code into more less duplicated form, from this original code: object FileMatcher { private def filesHere = (new java.io.File(".")).listFiles def filesEnding(query: String) = for (file <- filesHere; if file.getName.endsWith(query)) yield file def filesContaining(query: String) = for (file <- filesHere; if file.getName.contains(query)) yield file def filesRegex(query: String) = for (file <- filesHere; if file.getName.matches(query)) yield file } To the second version: object FileMatcher { private def filesHere = (new java.io.File(".")).listFiles def filesMatching(query: String, matcher: (String, String) => Boolean) = { for (file <- filesHere; if matcher(file.getName, query)) yield file } def filesEnding(query: String) = filesMatching(query, _.endsWith(_)) def filesContaining(query: String) = filesMatching(query, _.contains(_)) def filesRegex(query: String) = filesMatching(query, _.matches(_)) } Which they said that there is no use of closure here. Now I understand until this point. However they introduced the use of closure to refactor even some more, shown in Listing 9.1: object FileMatcher { private def filesHere = (new java.io.File(".")).listFiles private def filesMatching(matcher: String => Boolean) = for (file <- filesHere; if matcher(file.getName)) yield file def filesEnding(query: String) = filesMatching(_.endsWith(query)) def filesContaining(query: String) = filesMatching(_.contains(query)) def filesRegex(query: String) = filesMatching(_.matches(query)) } Now they said that query is a free variable but I don't really understand why they said so? Since ""query"" seems to be passed from top method down to string matching function explicitly.

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  • Scala method where type of second parameter equals part of generic type from first parameter

    - by ifischer
    I want to create a specific generic method in Scala. It takes two parameters. The first is of the type of a generic Java Interface (it's from the JPA criteria query). It currently looks like this: def genericFind(attribute:SingularAttribute[Person, _], value:Object) { ... } // The Java Interface which is the type of the first parameter in my find-method: public interface SingularAttribute<X, T> extends Attribute<X, T>, Bindable<T> Now i want to achieve the following: value is currently of type java.lang.Object. But I want to make it more specific. Value has to be the of the same type as the placeholder "_" from the first parameter (and so represents the "T" in the Java interface). Is that somehow possible, and how? BTW Sorry for the stupid question title (any suggestions?)

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  • Scala, make my loop more functional

    - by Pengin
    I'm trying to reduce the extent to which I write Scala (2.8) like Java. Here's a simplification of a problem I came across. Can you suggest improvements on my solutions that are "more functional"? Transform the map val inputMap = mutable.LinkedHashMap(1->'a',2->'a',3->'b',4->'z',5->'c') by discarding any entries with value 'z' and indexing the characters as they are encountered First try var outputMap = new mutable.HashMap[Char,Int]() var counter = 0 for(kvp <- inputMap){ val character = kvp._2 if(character !='z' && !outputMap.contains(character)){ outputMap += (character -> counter) counter += 1 } } Second try (not much better, but uses an immutable map and a 'foreach') var outputMap = new immutable.HashMap[Char,Int]() var counter = 0 inputMap.foreach{ case(number,character) => { if(character !='z' && !outputMap.contains(character)){ outputMap2 += (character -> counter) counter += 1 } } }

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  • Project Euler 10: (Iron)Python

    - by Ben Griswold
    In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 10.  As always, any feedback is welcome. # Euler 10 # http://projecteuler.net/index.php?section=problems&id=10 # The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. # Find the sum of all the primes below two million. import time start = time.time() def primes_to_max(max): primes, number = [2], 3 while number < max: isPrime = True for prime in primes: if number % prime == 0: isPrime = False break if (prime * prime > number): break if isPrime: primes.append(number) number += 2 return primes primes = primes_to_max(2000000) print sum(primes) print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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  • Can Scala be considered a functional superset of Java?

    - by Giorgio
    Apart from the differences in syntax, can Scala be considered a superset of Java that adds the functional paradigm to the object-oriented paradigm? Or are there any major features in Java for which there is no direct Scala equivalent? With major features I mean program constructs that would force me to heavily rewrite / restructure my code, e.g., if I had to port a Java program to Scala. Or can I expect that, given a Java program, I can port it to Scala almost line-by-line?

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  • Writing functions of tuples conveniently in Scala

    - by Alexey Romanov
    Quite a few functions on Map take a function on a key-value tuple as the argument. E.g. def foreach(f: ((A, B)) ? Unit): Unit. So I looked for a short way to write an argument to foreach: > val map = Map(1 -> 2, 3 -> 4) map: scala.collection.immutable.Map[Int,Int] = Map(1 -> 2, 3 -> 4) > map.foreach((k, v) => println(k)) error: wrong number of parameters; expected = 1 map.foreach((k, v) => println(k)) ^ > map.foreach({(k, v) => println(k)}) error: wrong number of parameters; expected = 1 map.foreach({(k, v) => println(k)}) ^ > map.foreach(case (k, v) => println(k)) error: illegal start of simple expression map.foreach(case (k, v) => println(k)) ^ I can do > map.foreach(_ match {case (k, v) => println(k)}) 1 3 Any better alternatives?

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  • Minimal framework in Scala for collections with inheriting return type

    - by Rex Kerr
    Suppose one wants to build a novel generic class, Novel[A]. This class will contain lots of useful methods--perhaps it is a type of collection--and therefore you want to subclass it. But you want the methods to return the type of the subclass, not the original type. In Scala 2.8, what is the minimal amount of work one has to do so that methods of that class will return the relevant subclass, not the original? For example, class Novel[A] /* What goes here? */ { /* Must you have stuff here? */ def reverse/* What goes here instead of :Novel[A]? */ = //... def revrev/*?*/ = reverse.reverse } class ShortStory[A] extends Novel[A] /* What goes here? */ { override def reverse: /*?*/ = //... } val ss = new ShortStory[String] val ss2 = ss.revrev // Type had better be ShortStory[String], not Novel[String] Does this minimal amount change if you want Novel to be covariant? (The 2.8 collections do this among other things, but they also play with return types in more fancy (and useful) ways--the question is how little framework one can get away with if one only wants this subtypes-always-return-subtypes feature.)

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