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  • Cannot access updated Java object from Saxon XSLT processor

    - by chipk
    I am working with an open source version of the Saxon XSLT processor "Saxon 9.0.0.2J from Saxonica" and am trying to make use of the java extensibility for the first time. I am running into an issue I suspect may be a limitation on the open source version, but wanted to check first whether there might be something I am just missing here. From the snippet below, my result is that the final value of $c1 does not change as a result of the call to greg:setTime() - i.e. the $c1 variable within Saxon appears to be unhooked from the underlying Java object and there is no apparent way to access the object as updated by the setTime() call. NOTE that all code in the snippet is tested and working otherwise - i.e. $c1 is properly instantiated by the getInstance() call, $startdate is of the proper format and $d1 is properly instantiated. Thoughts? <xsl:transform ..... xmlns:sql="java:java.sql.Date" xmlns:greg="java:java.util.GregorianCalendar" ..... > .... <xsl:element name="JobExpireDate"> <xsl:variable name="c1" select="greg:getInstance()" /> <xsl:variable name="d1" select="sql:valueOf($startdate)" /> <xsl:variable name="void" select="greg:setTime($c1,$d1)" /> <xsl:value-of select="$c1" /> </xsl:element>

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  • Java: What are the various available security settings for applets

    - by bguiz
    I have an applet that throws this exception when trying to communicate with the server (running on localhost). This problem is limited to Applets only - a POJO client is able to communicate with the exact same server without any problem. Exception in thread "AWT-EventQueue-1" java.security.AccessControlException: access denied (java.net .SocketPermission 127.0.0.1:9999 connect,resolve) at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) My applet.policy file's contents is: grant { permission java.security.AllPermission; }; My question is what are the other places where I need to modify my security settings to grant an Applet more security settings? Thank you. EDIT: Further investigation has lead me to find that this problem only occurs on some machines - but not others. So it could be a machine level (global) setting that is causing this, rather than a application-specific setting such as the one in the applet.policy file. EDIT: Another SO question: Socket connection to originating server of an unsigned Java applet This seems to describe the exact same problem, and Tom Hawtin - tackline 's answer provides the reason why (a security patch released that disallows applets from connecting to localhost). Bearing this in mind, how do I grant the applet the security settings such that in can indeed run on my machine. Also why does it run as-is on other machines but not mine?

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  • org.apache.cxf.interceptor.Fault: Unmarshalling Error: Duplicate default namespace declaration.

    - by JohnC
    Not sure why I am receiving this after the webservice ran and I am trying to return back to my client side bean. The webservice works perfectly outside of my webserver in SoapUI. org.apache.cxf.interceptor.Fault: Unmarshalling Error: Duplicate default namespace declaration. at [row,col {unknown-source}]: [1,321] at org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:764) at org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:623) at org.apache.cxf.jaxb.io.DataReaderImpl.read(DataReaderImpl.java:128) at org.apache.cxf.interceptor.DocLiteralInInterceptor.handleMessage(DocLiteralInInterceptor.java:101) at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:236) at org.apache.cxf.endpoint.ClientImpl.onMessage(ClientImpl.java:671) at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponseInternal(HTTPConduit.java:2177) at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponse(HTTPConduit.java:2057) at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.close(HTTPConduit.java:1982) at org.apache.cxf.transport.AbstractConduit.close(AbstractConduit.java:66) at org.apache.cxf.transport.http.HTTPConduit.close(HTTPConduit.java:637) at org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor.handleMessage(MessageSenderInterceptor.java:62) at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:236) at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:483) at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:309) at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:261) at org.apache.cxf.frontend.ClientProxy.invokeSync(ClientProxy.java:73) at org.apache.cxf.jaxws.JaxWsClientProxy.invoke(JaxWsClientProxy.java:124)

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  • An alternative to reading input from Java's System.in

    - by dvanaria
    I’m working on the UVa Online Judge problem set archive as a way to practice Java, and as a way to practice data structures and algorithms in general. They give an example input file to submit to the online judge to use as a starting point (it’s the solution to problem 100). Input from the standard input stream (java.lang.System.in) is required as part of any solution on this site, but I can’t understand the implementation of reading from System.in they give in their example solution. It’s true that the input file could consist of any variation of integers, strings, etc, but every solution program requires reading basic lines of text input from System.in, one line at a time. There has to be a better (simpler and more robust) method of gathering data from the standard input stream in Java than this: public static String readLn(int maxLg) { byte lin[] = new byte[maxLg]; int lg = 0, car = -1; String line = “”; try { while (lg < maxLg) { car = System.in.read(); if ((car < 0) || (car == ‘\n’)) { break; } lin[lg++] += car; } } catch (java.io.IOException e) { return (null); } if ((car < 0) && (lg == 0)) { return (null); // eof } return (new String(lin, 0, lg)); } I’m really surprised by this. It looks like something pulled directly from K&R’s “C Programming Language” (a great book regardless), minus the access level modifer and exception handling, etc. Even though I understand the implementation, it just seems like it was written by a C programmer and bypasses most of Java’s object oriented nature. Isn’t there a better way to do this, using the StringTokenizer class or maybe using the split method of String or the java.util.regex package instead?

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  • Connect to a site using proxy code in java

    - by Nithin
    I want to connect to as site through proxy in java.This is the code which I have written public class ConnectThroughProxy { Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("proxy ip", 8080)); public static void main(String[] args) { try{ URL url = new URL("http://www.rgagnon.com/javadetails/java-0085.html"); URLConnection connection=url.openConnection(); String encoded = new String(Base64.encode(new String("user_name:pass_word").getBytes())); connection.setDoOutput(true); connection.setRequestProperty("Proxy-Authorization","Basic "+encoded); String page=""; String line; StringBuffer tmp = new StringBuffer(); BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); while ((line=in.readLine()) != null){ page.concat(line + "\n"); } System.out.println(page); }catch(Exception ex){ ex.printStackTrace(); } } while trying to run this code it throws the following error java.lang.IllegalArgumentException: Illegal character(s) in message header value: Basic dXNlcl9uYW1lOnBhc3Nfd29yZA== at sun.net.www.protocol.http.HttpURLConnection.checkMessageHeader(HttpURLConnection.java:323) at sun.net.www.protocol.http.HttpURLConnection.setRequestProperty(HttpURLConnection.java:2054) at test.ConnectThroughProxy.main(ConnectThroughProxy.java:30) Any Idea how to do it.

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  • Trouble with Berkeley DB JE Base API Secondary Databases and Sequences

    - by milosz
    I have a class Document which consists of Id (int) and Url (String). I would like to have a primary index on Id and secondary index on Url. I would also like to have a sequence for Id auto-incrementation. So I create a SecondaryDatabase and then I create a Sequence. During initialisation of the Sequence I get an exception: Exception in thread "main" java.lang.IllegalArgumentException at com.sleepycat.util.UtfOps.getCharLength(UtfOps.java:137) at com.sleepycat.util.UtfOps.bytesToString(UtfOps.java:259) at com.sleepycat.bind.tuple.TupleInput.readString(TupleInput.java:152) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyDocumentBiding.entryToObject(MyDocumentBiding.java:12) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyDocumentBiding.entryToObject(MyDocumentBiding.java:1) at com.sleepycat.bind.tuple.TupleBinding.entryToObject(TupleBinding.java:76) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.UrlKeyCreator.createSecondaryKey(UrlKeyCreator.java:20) at com.sleepycat.je.SecondaryDatabase.updateSecondary(SecondaryDatabase.java:835) at com.sleepycat.je.SecondaryTrigger.databaseUpdated(SecondaryTrigger.java:42) at com.sleepycat.je.Database.notifyTriggers(Database.java:2004) at com.sleepycat.je.Cursor.putNotify(Cursor.java:1692) at com.sleepycat.je.Cursor.putInternal(Cursor.java:1616) at com.sleepycat.je.Cursor.putNoOverwrite(Cursor.java:663) at com.sleepycat.je.Sequence.<init>(Sequence.java:188) at com.sleepycat.je.Database.openSequence(Database.java:546) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyFullTextSearchEngine.init(MyFullTextSearchEngine.java:131) at pl.edu.mimuw.zbd.berkeley.zadanie.testy.MyFullTextSearchEngineTest.main(MyFullTextSearchEngineTest.java:18) It seems that during the initialisation of the sequence the secondary database is forced to update. When I debug the entryToObject method of MyDocumentBiding the bytes that it tries to convert to object seem random. What am I doing wrong?

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  • Switching from Java to .NET from a career change point of view

    - by Joe
    Could anyone share with me their experience with switching from Java to .NET from a career point of view? I've been a Java developer for 12 years and am just getting tired of how fragmented the Java world has become. For my liking, there's just too many frameworks, tools, application servers, etc.. And it seems each new tool just adds complexity and time to even the simplest of projects. I'm not trying to start any wars - I'm just giving you the reason I ask the main question. I've read a few books on .NET and have done one WebForms job. I love the integrated environment and would like to hear how others transitioned from Java to .NET. What I mean by that is did you do it somehow as a contractor or did you join a company as a beginner .NET developer with much Java experience? Personally, I'm ready to take the leap if I can figure out how to not lose too much income in the process (Senior Java developer to beginner .NET developer). I would really appreciate hearing your stories.

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  • java serialization problems with different JVMs

    - by Alberto
    I am having trouble using serialization in Java. I've searched the web for a solution but haven't found an answer yet. The problem is this - I have a Java library (I have the code and I export it to an archive prior to executing the code) which I need to use with two differents JVMs. One JVM is on the server (Ubuntu, running Java(TM) JRE SE Runtime Environment (build 1.7.0_09-b05)) and the other on Android 2.3.3. I compiled the library in Java 1.6. Now, I am trying to import to the client, an object exported from the server, but I receive this error: java.io.InvalidClassException: [Lweka.classifiers.functions.MultilayerPerceptron$NeuralEnd;; Incompatible class (SUID): [Lweka.classifiers.functions.MultilayerPerceptron$NeuralEnd;: static final long serialVersionUID =-359311387972759020L; but expected [Lweka.classifiers.functions.MultilayerPerceptron$NeuralEnd;: static final long serialVersionUID =1920571045915494592L; I do have an explicit serial version UID declared on the class MultilayerPerceptron$NeuralEnd, like this: protected class NeuralEnd extends NeuralConnection { private static final long serialVersionUID = 7305185603191183338L; } Where NeuralConnection implements the java.io.Serializable interface. If I do a serialver on MultilayerPerceptron$NeuralEnd I receive the serialVersionUID which I declared. So, why have both JVMs changed this value? Can you help me? Thanks, Alberto

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  • Java sound doesn't work under Linux

    - by Cliff
    Help! I'm getting frustrated by the individual hoops I have to go through to eek sound out of my speakers when running Java apps on Linux platforms! I just installed Fedora 12 and after downloading and running the Java Sound Demo I get exceptions. If I run just a vanilla Java program that plays a wav file it runs silently with no sound and no exceptions. Every other app seems to play sound. I also took some advice from this thread in the Ubuntu forums which almost seemed to work. (Installing aoss got rid of the initial exceptions in the sound demo but I still hear nothing when I play.) can somebody help me figure out what's wrong?

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  • Is 1/0 a legal Java expression?

    - by polygenelubricants
    The following compiles fine in my Eclipse: final int j = 1/0; // compiles fine!!! // throws ArithmeticException: / by zero at run-time Java prevents many "dumb code" from even compiling in the first place (e.g. "Five" instanceof Number doesn't compile!), so the fact this didn't even generate as much as a warning was very surprising to me. The intrigue deepens when you consider the fact that constant expressions are allowed to be optimized at compile time: public class Div0 { public static void main(String[] args) { final int i = 2+3; final int j = 1/0; final int k = 9/2; } } Compiled in Eclipse, the above snippet generates the following bytecode (javap -c Div0) Compiled from "Div0.java" public class Div0 extends java.lang.Object{ public Div0(); Code: 0: aload_0 1: invokespecial #8; //Method java/lang/Object."<init>":()V 4: return public static void main(java.lang.String[]); Code: 0: iconst_5 1: istore_1 // "i = 5;" 2: iconst_1 3: iconst_0 4: idiv 5: istore_2 // "j = 1/0;" 6: iconst_4 7: istore_3 // "k = 4;" 8: return } As you can see, the i and k assignments are optimized as compile-time constants, but the division by 0 (which must've been detectable at compile-time) is simply compiled as is. javac 1.6.0_17 behaves even more strangely, compiling silently but excising the assignments to i and k completely out of the bytecode (probably because it determined that they're not used anywhere) but leaving the 1/0 intact (since removing it would cause an entirely different program semantics). So the questions are: Is 1/0 actually a legal Java expression that should compile anytime anywhere? What does JLS say about it? If this is legal, is there a good reason for it? What good could this possibly serve?

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  • Some help required while working on Java and Cygwin together

    - by Hippo
    Hello .. I am new to java and also cygwin . I do not have in detailed knowledge of both . I need some help.. I simple steps i will try to explain my problem. 1) I am working on tinyOS . its open source OS , used for wireless sensor networks. It provides java libraries to work on communication (PC to sensor) 2) I am working on windows xp environment through cigwin. 3) I am developing an application . THis application requires one java interface called "Serial Forwarder" , which is readily available in libraries provided. Previously i used to start this interface manually (by entering command *"java net.tinyos.sf.SerialForwarder ")*and then my application which uses this interface. But now i want to make my application independent . User need know about this background cygwin commands . 4) So in my java application i used "Runtime.getRuntime().exec( "java net.tinyos.sf.SerialForwarder)" . 5) This i neither giving any error nor starting the interface. Am I going on right way ? When i am using runtime execute command , how can i make sure that this command is called through cigwin interface ? Also .. if i want to write .bat file .. i which i can give commands which will be executed .. how can i make sure that those commands are given through cigwin .. and not through cmd.exe .. Please help . me .

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  • Working with mongodb from Java

    - by demas
    I have launch mongodb server: [[email protected]][~]% mongod --dbpatmongod --dbpath /home/demas/temp/ Mon Apr 19 09:44:18 Mongo DB : starting : pid = 4538 port = 27017 dbpath = /home/demas/temp/ master = 0 slave = 0 32-bit ** NOTE: when using MongoDB 32 bit, you are limited to about 2 gigabytes of data ** see http://blog.mongodb.org/post/137788967/32-bit-limitations for more Mon Apr 19 09:44:18 db version v1.4.0, pdfile version 4.5 Mon Apr 19 09:44:18 git version: nogitversion Mon Apr 19 09:44:18 sys info: Linux arch.local.net 2.6.33-ARCH #1 SMP PREEMPT Mon Apr 5 05:57:38 UTC 2010 i686 BOOST_LIB_VERSION=1_41 Mon Apr 19 09:44:18 waiting for connections on port 27017 Mon Apr 19 09:44:18 web admin interface listening on port 28017 I have created documents by console client: [[email protected]][~]% mongo MongoDB shell version: 1.4.0 url: test connecting to: test type "help" for help > db.some.find(); { "_id" : ObjectId("4bcbef3c3be43e9b7e04ef3d"), "name" : "mongo" } { "_id" : ObjectId("4bcbef423be43e9b7e04ef3e"), "x" : 3 } Now I am trying to work with MongoDb from Java: import com.mongodb.*; import java.net.UnknownHostException; public class test1 { public static void main(String[] args) { System.out.println("Start"); try { Mongo m = new Mongo("localhost", 27017); DB db = m.getDB("test"); DBCollection coll = db.getCollection("some"); coll.insert(makeDocument(10, "James", "male")); System.out.println("Finish"); } catch (UnknownHostException ex) { ex.printStackTrace(); } catch (MongoException ex) { ex.printStackTrace(); } } public static BasicDBObject makeDocument(int id, String name, String gender) { BasicDBObject doc = new BasicDBObject(); doc.put("id", id); doc.put("name", name); doc.put("gender", gender); return doc; } } But execution stops on line coll.insert(): [[email protected]][~/dev/study/java/mongodb]% javac test1.java [[email protected]][~/dev/study/java/mongodb]% java test1 Start There are not messages from mogodb server regarding accepted connection. Why?

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  • Calling Java classes from IzPack

    - by bguiz
    I am trying to write an IzPack installer which is able to detect a previously installed version of the application. After finding out that it doesn't really support this feature, I think the only way to do this is through writing a Java class and calling it from IzPack. Tim Williscroft has previously suggested this method: <condition type="java" id="jbossEnv"> <java> <class>au.com.codarra.ela.installer.JBossChecker</class <field>hasJBossEnv</field> </java> <returnvalue type="boolean">true</returnvalue> </condition> However, is it possible to call <java> from somewhere other than a <condition> tag? I want to be able to call it from a <variable> tag. Also, is it possible to call a method from a Java class instead of reading a value of a field? I want to be able to pass parameters to my class. Thank you!

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  • Performance of Java matrix math libraries?

    - by dfrankow
    We are computing something whose runtime is bound by matrix operations. (Some details below if interested.) This experience prompted the following question: Do folk have experience with the performance of Java libraries for matrix math (e.g., multiply, inverse, etc.)? For example: JAMA: http://math.nist.gov/javanumerics/jama/ COLT: http://acs.lbl.gov/~hoschek/colt/ Apache commons math: http://commons.apache.org/math/ I searched and found nothing. Details of our speed comparison: We are using Intel FORTRAN (ifort (IFORT) 10.1 20070913). We have reimplemented it in Java (1.6) using Apache commons math 1.2 matrix ops, and it agrees to all of its digits of accuracy. (We have reasons for wanting it in Java.) (Java doubles, Fortran real*8). Fortran: 6 minutes, Java 33 minutes, same machine. jvisualm profiling shows much time spent in RealMatrixImpl.{getEntry,isValidCoordinate} (which appear to be gone in unreleased Apache commons math 2.0, but 2.0 is no faster). Fortran is using Atlas BLAS routines (dpotrf, etc.). Obviously this could depend on our code in each language, but we believe most of the time is in equivalent matrix operations. In several other computations that do not involve libraries, Java has not been much slower, and sometimes much faster.

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  • ClassNotFoundException com.mysql.jdbc.Driver

    - by Dusk
    This question might have asked here number of times . After doing some google search for the above error and doing some update, I can't understand why I'm still getting that error. I've already put my driver-- mysql-connector-java-5.1.5-bin in the classpath: Java_Home\jre\lib\ Java_Home\jre\lib\ext\ Java_Home\lib and the code which I'm using to connect to mysql database is: try{ Class.forName("com.mysql.jdbc.Driver"); Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mail","root",""); Statement stmt = con.createStatement(); ResultSet rs = stmt.executeQuery("select message_body from deadletter"); String dbtime; while (rs.next()) { dbtime = rs.getString(1); System.out.println(dbtime); } con.close(); } catch (SQLException e) { System.out.println("Connection Failed! Check output console"); e.printStackTrace(); } } and the complete stacktrace of the above exception is: java.lang.ClassNotFoundException: com.mysql.jdbc:Driver at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:307) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at mail.main(mail.java:114) Now, what's wrong I'm doing here?

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  • java bubblesort with acm dialog

    - by qzar
    Hi, the program gives following exception: Exception in thread "main" java.lang.NullPointerException at myclasses.BubbleSort.run(BubbleSort.java:42) at acm.program.Program.runHook(Program.java:1519) at acm.program.Program.startRun(Program.java:1508) at acm.program.Program.start(Program.java:729) at myclasses.BubbleSort.main(BubbleSort.java:49) what is wrong? thank you very much! package myclasses; import acm.program.DialogProgram; public class BubbleSort extends DialogProgram { int[] array; public int[] getArray() { return array; } public void setArray(int[] array) { this.array = array; } void swap(int firstPos, int secondPos) { int temp = array[firstPos]; array[firstPos] = array[secondPos]; array[secondPos] = temp; } public void bubblesort() { int i, j, k; for (i = 1; i < array.length; i++) { j = i; k = array[i]; while (j > 0 && array[j - 1] > k) { array[j] = array[j - 1]; --j; } array[j] = k; } } public void run() { BubbleSort a = new BubbleSort(); a.setArray(new int[] {1, 3, 5, 7, 6, 2}); a.bubblesort(); StringBuffer sb = new StringBuffer(a.array.length * 2); for (int i = 0; i < getArray().length; i++) sb.append(getArray()[i]).append(" "); println(sb); } public static void main(String[] args) { new BubbleSort().start(args); } }

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  • Longer execution through Java shell than console?

    - by czuk
    I have a script in Python which do some computations. When I run this script in console it takes about 7 minutes to complete but when I run it thought Java shell it takes three times longer. I use following code to execute the script in Java: this.p = Runtime.getRuntime().exec("script.py --batch", envp); this.input = new BufferedReader(new InputStreamReader(p.getInputStream())); this.output = new BufferedWriter(new OutputStreamWriter(p.getOutputStream())); this.error = new BufferedReader(new InputStreamReader(p.getErrorStream())); Do you have any suggestion why the Python script runs three time longer in Java than in a console? update The computation goes as follow: Java sends data to the Python. Python reads the data. Python generates a decision tree --- this is a long operation. Python sends a confirmation that the tree is ready. Java receives the confirmation. Later there is a series of communications between Java and Python but it takes only several second.

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  • Java Class<T> static method forName() IncompatibleClassChangeError

    - by matt
    Hi, i have this code: private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = Class.forName(s).asSubclass(Importable.class); Importable i = c.newInstance(); return i; } which i can also write private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = (Class<? extends Importable>)Class.forName(s); Importable i = c.newInstance(); return i; } or private static Importable getRightInstance(String s) throws Exception { Class<?> c = Class.forName(s); Importable i = (Importable)c.newInstance(); return i; } where Importable is an interface and s is a string representing an implementing class. Well, in any case it gives the following: Exception in thread "main" java.lang.IncompatibleClassChangeError: class C1 has interface Importable as super class Here is the last snippet of the stack trace: at java.lang.Class.forName(Class.java:169) at Importer.getRightImportable(Importer.java:33) at Importer.importAll(Importer.java:44) at Test.main(Test.java:16) Now, class C1 actually implemens Importable and i totally don't understand why it complaints. Thanks in advance.

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  • Java constructor using generic types

    - by Beer Me
    I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method breweryMethod() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // breweryMethod() is an instance method // of Brewery, of which <T> is a subclass (right?) c.breweryMethod(); // "The method breweryMethod() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void brewerySubClassMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

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  • Is app stability unusually hard with Java?

    - by wrp
    Java's extensive libraries and tool support are appealing, but I've never tried developing with it because most Java applications I've used have been extremely buggy. This has me puzzled, because I hear that Java is the dominant platform for enterprise development. Maybe it's fine for server-side stuff but not desktop applications. I'm not talking about things like the long compile/startup times or the random latencies due to garbage collection. This is about things just going wrong. Some of the most common problems I see are: corrupted icons corrupted fonts, in menus usually and editing areas sometimes inaccurate framing of GUI elements dialogs sometimes popping up blank Maybe the problems are mostly with Swing. I've rarely used a Java application long enough to find deeper issues. I can think of a few possible explanations for what I've experienced: It's possible to write stable apps with Java, just harder. Java apps are always buggy and enterprise users just put up with it. Server-side apps are fine because just Swing is buggy. I'm living under a curse and need the services of a good witchdoctor.

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  • Java constructor using generic types

    - by user37903
    I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method initBreweryFromObject() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // initBreweryFromObject() is an instance method // of Brewery, of which <T> is a subclass (right?) c.initBreweryFromObject(); // "The method initBreweryFromObject() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void androidMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

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  • Java program using a class from a JAR file

    - by Myn
    Hi guys, I'll try to phrase this as best I can. I have a program which has an API-like functionality - it uses reflection to dynamically call methods from within a class. In this instance: Server.java public static void main(String[] args) { Class<?> clazz = Class.forName("DiHandler"); StHandler out = (StHandler) clazz; out.read(); DiHandler.java // implements StHandler import edu.ds.*; public void read() { Ds aType = new Ds(); aType = "134"; } So DiHandler has a method read() which can contain anything, it doesn't matter to Server.java after compile time. My problem is: DiHandler.java uses the class Ds from a JAR file. When I'm working on DiHandler.java in Eclipse (in a separate project from the project Server.java is in) I can add this JAR without a problem. But when I move DiHandler.class, after it's compiled, to be used by Server.class, how can it still use the JAR file? I hope this makes some sense, I suppose another way to phrase it would be how can I allow DiHandler to call on a class from the JAR without editing the classpath? Thanks very much in advance and sorry for any confusion or poor phrasing, I can only offer thanks and the customary offer of a pint for any assistance. M

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  • Java Equivalent of C++ .dll?

    - by Matt D
    So, I've been programming for a while now, but since I haven't worked on many larger, modular projects, I haven't come across this issue before. I know what a .dll is in C++, and how they are used. But every time I've seen similar things in Java, they've always been packaged with source code. For instance, what would I do if I wanted to give a Java library to someone else, but not expose the source code? Instead of the source, I would just give a library as well as a Javadoc, or something along those lines, with the public methods/functions, to another programmer who could then implement them in their own Java code. For instance, if I wanted to create a SAX parser that could be "borrowed" by another programmer, but (for some reason--can't think of one in this specific example lol) I don't want to expose my source. Maybe there's a login involved that I don't want exploited--I don't know. But what would be the Java way of doing this? With C++, .dll files make it much easier, but I have never run into a Java equivalent so far. (I'm pretty new to Java, and a pretty new "real-world" programmer, in general as well)

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  • How to connect SQLite with Java?

    - by Rajapandian
    Hi, I am using one simple code to access the SQLite database from Java application . My code is import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ConnectSQLite { public static void main(String[] args) { Connection connection = null; ResultSet resultSet = null; Statement statement = null; try { Class.forName("org.sqlite.JDBC"); connection = DriverManager.getConnection("jdbc:sqlite:D:\\testdb.db"); statement = connection.createStatement(); resultSet = statement .executeQuery("SELECT EMPNAME FROM EMPLOYEEDETAILS"); while (resultSet.next()) { System.out.println("EMPLOYEE NAME:" + resultSet.getString("EMPNAME")); } } catch (Exception e) { e.printStackTrace(); } finally { try { resultSet.close(); statement.close(); connection.close(); } catch (Exception e) { e.printStackTrace(); } } } } But this code gives one exception like java.lang.ClassNotFoundException: org.sqlite.JDBC Any body knows how to slove it,please help me.

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  • StackOverflow Error at java.util.AbstractColllection.<init>(Unknown Source)

    - by thebulge
    I fixed my prior problem yesterday by just separating all the classes into separate files. Nevertheless, I wrote all the code down and seeing no errors was able to compile the program. Or so I thought. Here's the error code: Exception in thread "main" java.lang.StackOverflowError at java.util.AbstractCollection.<init>(Unknown Source) at java.util.AbstractList.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source Here are the spots where my I get the errors(marked with problem?) public class GameWorld implements IObservable, IGameWorld { // create collections class public Vector<GameObject> GameObjectList = new Vector<GameObject>(); // PROBLEM private Vector<IObserver> ObserverList = new Vector<IObserver>(); // declare objects Tank pTank = new Tank(10, 10); // other objects and variables to declare public GameWorld() { // add objects to GameObjectList } // accessors/mutators } I get another error here public class Tank extends Movable implements ISteerable { private int armorStrength; private int missileCount; public Tank() {} public Tank(int armStr, int misslCt) // problem? { armorStrength = armStr; // default armorStrength missileCount = misslCt; // default missileCount } public void setDirection(int direction) { this.setDirection(direction); // get input from left turn or right turn // updateValues(); } // access/mutators here I'm stumped on what to do here.

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