This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
I currently am trying to make a risk-like game and as I try to display a map (vectorial image) I have a NullPointerException that I do not understand at all how it can be solved. =/
Here's the code :
public class Test1 extends Stage {
private BorderPane root = new BorderPane();
private WebView browser = new WebView();
public Test1(){
this.setTitle("Test1");
this.setScene(new Scene(content()));
}
Parent content(){
WebEngine webEngine = browser.getEngine();
webEngine.load(this.getClass().getResource("../../resources/worldMap.html").toExternalForm());
root.setCenter(browser);
return root;
}
}
and the error :
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at hmi.Test1.content(Test1.java:23)
at hmi.Test1.<init>(Test1.java:18)
at Main.start(Main.java:13)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
... 1 more
Exception running application Main
So it seems to be caused by the link "../../resources/worldMap.html" but it really leads to the file. I also tried with a svg file or with an url (this one : https://upload.wikimedia.org/wikipedia/commons/8/80/World_map_-_low_resolution.svg )
and I still have the exact same error.
It's been a day I'm stuck on that despite my researchs on internet, so I hope you will be able to help me.
Thanks !
I can't say for certain from the pasted code, but I think I can help you debug it. You've identified webEngine.load(this.getClass().getResource("../../resources/worldMap.html").toExternalForm()); as the errant line in one of your comments.
The NPE means one of the things you are using in that line is null in an unexpected way. Are you using an IDE with a debugger? Set a break-point on that line and evaluate each subcomponent.
If not, you really should try one. I use intellij and find it makes me far more effective and efficient. In the interim, the hackiest simplest way to figure this out is with a bunch of print statements
System.out.println("webEngine" + webEngine);
System.out.println("class" + this.getClass());
System.out.println("resource" + this.getClass().getResource("../../resources/worldMap.html"));
System.out.println("loaded" + webEngine.load(this.getClass().getResource("../../resources/worldMap.html"));
One of these things will be null and the next line will throw an NPE. That way, you'll know where in the stack you have a problem. Please post back when you find it. I would guess that either using the this.getClass.getResource is wrong or the place you think the relative path starts from in your path string is wrong (usually it is relative to where your .class paths are written).
Have you tried using an absolute path instead to load your resource? It's possible where you think your code is executing from and where it's actually executing from are different.
Ok, I finally found out the answer.
My question is actually a duplicate of Class.getResource() returns null
And the answer was that the image had to be in the same directory as the package where the class on which I apply the "getclass" is, while it was in the root of the project.
Thank you for your help though !
Related
Some of our Windows users get this stack trace shortly after launching our app:
java.lang.InternalError: Could not bind shell folder to interface
at sun.awt.shell.Win32ShellFolder2.initSpecial(Native Method) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2.access$300(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2$1.call(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2$1.call(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolderManager2$ComInvoker.invoke(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.ShellFolder.invoke(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2.<init>(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolderManager2.getNetwork(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2.getFileSystemPath(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2.access$400(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2$10.call(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolder2$10.call(Unknown Source) ~[na:1.7.0_25]
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) ~[na:1.7.0_25]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[na:1.7.0_25]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) ~[na:1.7.0_25]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) ~[na:1.7.0_25]
at sun.awt.shell.Win32ShellFolderManager2$ComInvoker$3.run(Unknown Source) ~[na:1.7.0_25]
at java.lang.Thread.run(Unknown Source) ~[na:1.7.0_25]
Observations:
Every frame in the stack trace is something in the JDK, not in our code.
This happens only on Windows, but we've had reports of it on both Vista and Windows 7.
This happens with various versions of Java: 1.6.0_19, 1.6.0_21, 1.7.0_11, 1.7.0_25.
The problem happens to only a handful of our users, but is 100% repeatable for those users. Unfortunately, we haven't been able to see anything which those users' systems have in common other than exhibiting this issue, and none of our developers has ever experienced it themselves.
My search of Oracle's bug database turned up no bugs with the same or a similar stack trace.
There seem to be a lot of posts on the net about this particular issue without anyone having any idea what causes it.
I'm not holding out any hope of Oracle fixing whatever the problem is, if it is indeed a JDK bug---but if we knew what triggered the bug, we could at least help our users afflicted by it. Can anyone shed light on what causes this to happen?
Edit: The relevant native function is this one, from ShellFolder2.cpp:
JNIEXPORT void JNICALL Java_sun_awt_shell_Win32ShellFolder2_initSpecial
(JNIEnv* env, jobject folder, jlong desktopIShellFolder, jint folderType)
{
// Get desktop IShellFolder interface
IShellFolder* pDesktop = (IShellFolder*)desktopIShellFolder;
if (pDesktop == NULL) {
JNU_ThrowInternalError(env, "Desktop shell folder missing");
return;
}
// Get special folder relative PIDL
LPITEMIDLIST relPIDL;
HRESULT res = fn_SHGetSpecialFolderLocation(NULL, folderType,
&relPIDL);
if (res != S_OK) {
JNU_ThrowIOException(env, "Could not get shell folder ID list");
return;
}
// Set field ID for relative PIDL
env->CallVoidMethod(folder, MID_relativePIDL, (jlong)relPIDL);
// Get special folder IShellFolder interface
IShellFolder* pFolder;
res = pDesktop->BindToObject(relPIDL, NULL, IID_IShellFolder,
(void**)&pFolder);
if (res != S_OK) {
JNU_ThrowInternalError(env,
"Could not bind shell folder to interface");
return;
}
// Set field ID for pIShellFolder
env->CallVoidMethod(folder, MID_pIShellFolder, (jlong)pFolder);
}
In order to reach the "Could not bind" exception, it looks like pDesktop != NULL and relPIDL is retrieved successfully, but pDesktop->BindToObject() returns something other than S_OK. pDesktop is an IShellFolder*, which is apparently defined in Windows's <shellapi.h>. Aggravatingly, Java throws away the error code returned by IShellFolder::BindToObject.
So, I guess the question reduces to: What can cause IShellFolder::BindToObject to fail?
Edit 2: Since Win32ShellFolderManager2.getNetwork() is what's calling the Win32ShellFolder2 ctor at Win32ShellFolderManager2.java:181, we can see that the last argument to Win32ShellFolder2.initSpecial must be Win32ShellFolder2.NETWORK. So, is something is wrong with the user's Network Neighborhood folder, perhaps?
Well, there are several reports similar to yours (like this one from jEdit, this one from codenameone and this one - in german - which seems like a JFileChooser bug with a stack trace very close to yours in Windows 7 and Java 6). All seem related to JFileChooser and/or File Browsing in one way or another.
So I would approach this in one of two ways:
Either go for the time-consuming / non speculative road and take dumps of the affected installations with tools such as jstack, VisualVM or JConsole until you are able to isolate the root cause of the problem (which may or may not be the JFileChooser). If you choose that path, remember that either remote access to one of the affected installations or help from a technical savvy user is a must.
Or try to take a shortcut, assume that the problem is indeed the JFileChooser (as anecdotal evidence shows) and release a custom version replacing the JFileChooser by FileDialog. If it runs as expected on the affected machines case is closed; else give yourself a tap on the back for trying and take "The Long and Winding Road".
Had same problem and the answer was
java.awt.FileDialog
If you look up VbScript solutions for "Open File Dialog", it seems that there is no COM class doing the job for most of the windows platforms
I'd like to read different kinds of objects from file to an ArrayList, all of them are instances of class which extend the class Advertisement. I'm trying with this code:
ArrayList <Advertisement> ads = new ArrayList<Advertisement>();
ObjectInput input2 = new ObjectInputStream(
new BufferedInputStream(new FileInputStream("ads.ser")));
//break from this method at this point
ads = (ArrayList<Advertisement>) input2.readObject();
The problem is at the 3rd line/last line. It doesn't read the objects in variable ads of type ArrayList<Advertisement>, furthermore, it breaks from this method, without any messages.
Edit: Removed the try-catch block, I should have done it earlier, but I still don't know the solution. Stacktrace:
java.io.InvalidClassException: Kiado; local class incompatible: stream classdesc serialVersionUID = -1393576200767336208, local class serialVersionUID = -841663850423605586
at java.io.ObjectStreamClass.initNonProxy(Unknown Source)
at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source)
at java.io.ObjectInputStream.readClassDesc(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at java.util.ArrayList.readObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at Main.beolvasas(Main.java:30)
at Main.startup(Main.java:57)
at Main.main(Main.java:633)
Now that you have a stack trace, the problem is clear: since the moment you serialized the objects to the file, you have made changes to the class Kiado. So the class you have now is not compatible anymore with the class as it was when serializing the objects to the file.
If you didn't change the number and the names of the fields of the class (and of all its superclasses), you can make it compatible again by just adding the following variable declaration in the class:
private static final long serialVersionUID = -1393576200767336208;
If you added, removed or renamed at least one (non-transient) field, then you might make the new class still compatible with the old one, but with more pain. And we would have to know the nature of the changes to help you.
I would personally avoid using native serialization for long-term storage because, as you just noticed, it's fragile and makes it hard to change the model. I would use a more easily readable and migratable file format: XML or JSON for example.
Do you have any code like:
catch(<WheteverException> e)
{
// nothing here
}
If so do the following:
change the // nothing here to e.printStackTrace();
remove the try/catch and only add it back if the compiler tells you to, and then only add back what exception that the compiler tells you to add (for instance don't do catch(Exception e).
I am trying to compress a graph using the WebGraph framework. I have set up the jars I need and I use the following code:
ImmutableGraph ig = ArcListASCIIGraph.load(BoldiTest.class.getResource("/citation-csconf-mult5-PaperJSON.graph.txt").getFile());
System.out.println(ig.numNodes()+" "+ig.numArcs());
ImmutableGraph.store(BVGraph.class, ig, "output");
The graph is loaded correctly but fails to be stored for the graph I am interested. For a much smaller graph (3 arcs) everything goes well so I guess the code is correct.
I provide the Stack Trace below. Any ideas? (the numbers are nodes and arcs)
124538 249755
Exception in thread "main" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at it.unimi.dsi.big.webgraph.ImmutableGraph.store(ImmutableGraph.java:623)
at it.unimi.dsi.big.webgraph.ImmutableGraph.store(ImmutableGraph.java:638)
at gr.di.uoa.a8.boldi.BoldiTest.main(BoldiTest.java:22)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at it.unimi.dsi.big.webgraph.ImmutableGraph.store(ImmutableGraph.java:619)
... 2 more
Caused by: java.lang.ArrayIndexOutOfBoundsException: -1
at it.unimi.dsi.big.webgraph.BVGraph.updateBins(BVGraph.java:1701)
at it.unimi.dsi.big.webgraph.BVGraph.storeInternal(BVGraph.java:1808)
at it.unimi.dsi.big.webgraph.BVGraph.store(BVGraph.java:1650)
at it.unimi.dsi.big.webgraph.BVGraph.store(BVGraph.java:1678)
at it.unimi.dsi.big.webgraph.BVGraph.store(BVGraph.java:1690)
... 7 more
After eliminating the duplicate edges and sorting the input file I managed to store the graph.
i am learning JAXb 2.0 and is new to it.
i am trying to generate XSD based on y POJO classes using schemagen and for simple classes it working fine but when my class contains refrence to other classes
schemagen is giving me error below is the error trace for the same
Problem encountered during annotation processing;
see stacktrace below for more information.
java.lang.NullPointerException
at com.sun.tools.jxc.model.nav.APTNavigator$2.onDeclaredType(APTNavigator.java:436)
at com.sun.tools.jxc.model.nav.APTNavigator$2.onClassType(APTNavigator.java:410)
at com.sun.tools.jxc.model.nav.APTNavigator$2.onClassType(APTNavigator.java:464)
at com.sun.istack.tools.APTTypeVisitor.apply(APTTypeVisitor.java:27)
at com.sun.tools.jxc.model.nav.APTNavigator.getBaseClass(APTNavigator.java:113)
at com.sun.tools.jxc.model.nav.APTNavigator.getBaseClass(APTNavigator.java:89)
at com.sun.xml.bind.v2.model.impl.PropertyInfoImpl.getIndividualType(PropertyInfoImpl.java:195)
at com.sun.xml.bind.v2.model.impl.PropertyInfoImpl.<init>(PropertyInfoImpl.java:137)
at com.sun.xml.bind.v2.model.impl.MapPropertyInfoImpl.<init>(MapPropertyInfoImpl.java:71)
at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.createMapProperty(ClassInfoImpl.java:928)
at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.addProperty(ClassInfoImpl.java:885)
at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.findGetterSetterProperties(ClassInfoImpl.java:1004)
at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.getProperties(ClassInfoImpl.java:314)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:247)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:213)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:319)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:334)
at com.sun.tools.xjc.api.impl.j2s.JavaCompilerImpl.bind(JavaCompilerImpl.java:94)
at com.sun.tools.jxc.apt.SchemaGenerator$1.process(SchemaGenerator.java:119)
at com.sun.mirror.apt.AnnotationProcessors$CompositeAnnotationProcessor.process(AnnotationProcessors.java:60)
at com.sun.tools.apt.comp.Apt.main(Apt.java:454)
at com.sun.tools.apt.main.JavaCompiler.compile(JavaCompiler.java:258)
at com.sun.tools.apt.main.Main.compile(Main.java:1102)
at com.sun.tools.apt.main.Main.compile(Main.java:964)
at com.sun.tools.apt.Main.processing(Main.java:95)
at com.sun.tools.apt.Main.process(Main.java:85)
at com.sun.tools.apt.Main.process(Main.java:67)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.tools.jxc.SchemaGenerator$Runner.main(SchemaGenerator.java:245)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.tools.jxc.SchemaGenerator.run(SchemaGenerator.java:177)
at com.sun.tools.jxc.SchemaGenerator.run(SchemaGenerator.java:81)
at com.sun.tools.jxc.SchemaGenerator.main(SchemaGenerator.java:73)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.tools.jxc.SchemaGeneratorFacade.main(SchemaGeneratorFacade.java:60)
C:\Users\Desktop\jaxb\jaxb-ri-20101119\bin\src\com\tr\model\destination\Destination.java:9: package com.tr.model.address does not exist
import com.tr.model.address.BasicAddress;[code]
below is the detail of my folder structure
schemagen is located at the following location
C:\Users\Desktop\jaxb\jaxb-ri-20101119\bin
My Java class based on which i am trying to generate xsd is at the following location
C:\Users\Desktop\jaxb\jaxb-ri-20101119\bin\src\com\tr\model\destination
Destination.java
while all other classes being refrenced from Destination as well as the class itself are inside the following structure
C:\Users\Raisonne\Desktop\jaxb\jaxb-ri-20101119\bin\src\com\raisonne\tr\model
i know the problem is with the setting of classpath but i am unable to figure it out ho to set correct classpath for this case
i tried to set system's CLASSPATH variable to the value of
C:\Users\Raisonne\Desktop\jaxb\jaxb-ri-20101119\bin\src\com\raisonne\tr\model as well other 2 mentioned in my post but nothing worked out.
can any one help me in setting classpath for the schemagen.
thanks in advance
Umesh
it seems you have set package declaration of your class to
com.tr.model.address
where it should be from your dir structure
com.tr.model.destination
As part of some simulations that I am running using a tool called JIST/SWANS I am getting some weird errors. This simulator has been written for Java 1.4 and I am attempting to port it to 1.5.
What I am trying to do is to compile the original code with the 1.5 SDK. The problem is that the simulator uses bcel to rewrite the bytecode so that JVM could be used for simulations. When I compile the code under the new SDK, I get the error given below. Can someone point me in the right direction to fix this? I know the byte code produced by 1.4 and 1.5 are somewhat different but I have no clue where to start looking from.
java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.remove(ArrayList.java:390)
at org.apache.bcel.verifier.structurals.OperandStack.pop(OperandStack.java:135)
at org.apache.bcel.verifier.structurals.ExecutionVisitor.visitPUTFIELD(ExecutionVisitor.java:1048)
at org.apache.bcel.generic.PUTFIELD.accept(PUTFIELD.java:78)
at jist.runtime.RewriterFlow.execute(RewriterFlow.java:235)
at jist.runtime.RewriterFlow.doFlow(RewriterFlow.java:187)
at jist.runtime.RewriterTraversalContinuableMethods.doMethod(Rewriter.java:3059)
at jist.runtime.ClassTraversal.processMethodGen(ClassTraversal.java:136)
at jist.runtime.ClassTraversal.processClassGen(ClassTraversal.java:96)
at jist.runtime.ClassTraversal.processClass(ClassTraversal.java:63)
at jist.runtime.Rewriter.rewriteClass(Rewriter.java:621)
at jist.runtime.Rewriter.findClass(Rewriter.java:410)
at jist.runtime.Rewriter.loadClass(Rewriter.java:367)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)
at java.lang.Class.getDeclaredMethod(Class.java:1935)
at jist.swans.app.AppJava.findMain(AppJava.java:86)
at jist.swans.app.AppJava.<init>(AppJava.java:61)
at driver.aodvtest.createNode(aodvtest.java:192)
at driver.aodvtest.createSim(aodvtest.java:235)
at driver.aodvtest.main(aodvtest.java:277)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at jist.runtime.Bootstrap$JavaMain.startSimulation(Bootstrap.java:163)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at jist.runtime.Controller.processEvent(Controller.java:650)
at jist.runtime.Controller.eventLoop(Controller.java:428)
at jist.runtime.Controller.run(Controller.java:457)
at java.lang.Thread.run(Thread.java:619)
java.lang.NullPointerException
at driver.aodvtest.createNode(aodvtest.java:198)
at driver.aodvtest.createSim(aodvtest.java:235)
at driver.aodvtest.main(aodvtest.java:277)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at jist.runtime.Bootstrap$JavaMain.startSimulation(Bootstrap.java:163)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at jist.runtime.Controller.processEvent(Controller.java:650)
at jist.runtime.Controller.eventLoop(Controller.java:428)
at jist.runtime.Controller.run(Controller.java:457)
at java.lang.Thread.run(Thread.java:619)
UPDATE:
I narrowed down to this line from where the exception is being thrown:
private Method findMain(Class<?> c) throws NoSuchMethodException {
return c.getDeclaredMethod("main", new Class<?>[] { String[].class });
}
There is a main method in the class which is being passed to this function so I have no clue why it is returning a null.
UPDATE 2:
There is one function:
createNode(..., ..., ..., ..., MyClient.class, ..., ...)
which passes the MyClient.class to a function that makes use of this in the findMain method posted above. Using the debugger, I can see that declaredMethods is null so obviously the getDeclaredMethods call is dying. The MyClient class is defined as an inner static class in the following way:
public static class MyClient {
public static void main(String[] args[]) {
...
}
}
I am not sure if this has anything to do with declaredMethods being null so I tried extracting the class into a separate class but with no luck.
UPDATE 3:
Ok narrowed it down. The following throws an exception even in the main class:
System.out.println(MyClient.class.getDeclaredMethods());
Perhaps downloading BCEL's source code and putting a breakpoint at line 135 of this method
org.apache.bcel.verifier.structurals.OperandStack.pop(OperandStack.java:135)
will tell you more. Obviously, there's a problem somewhere with array index manipulation.
From what I see, BCEL is no more in development, so if a bug exists, it might be difficult to have it fixed if you report it.
ASM is a more modern bytecode generation library that's under development. You probably already know this; but if you have that simulator's source code and it isn't using BCEL too much, you might be able to rewrite it using ASM. Of course, stuff like this is usually overkill.