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Issue displaying a map with java [duplicate]

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 !

NullPointerException at java.util.logging.Logger.demandLogger

After upgrading from Java 6 to Java 8, my application throws the following exception:
com.mathworks.toolbox.javabuilder.MWException: Java exception occurred:
java.lang.NullPointerException
at java.util.logging.Logger.demandLogger(Logger.java:451)
at java.util.logging.Logger.getLogger(Logger.java:502)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.mclFeval(Native Method)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.access$600(MWMCR.java:23)
at com.mathworks.toolbox.javabuilder.internal.MWMCR$6.mclFeval(MWMCR.java:833)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.mathworks.toolbox.javabuilder.internal.MWMCR$5.invoke(MWMCR.java:731)
at com.sun.proxy.$Proxy2.mclFeval(Unknown Source)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.invoke(MWMCR.java:406)
at mDataEngine.mDataEngineMIF.volatility(mDataEngineMIF.java:7212)
This occurs when using the mathworks library, which in turn uses java.util.logging.Logger where the exception is thrown.

This can be solved by setting the following system property when starting the Java program:
-Dsun.util.logging.disableCallerCheck=true
More detailed information:
The reason for the NullpointerException seems to be explained here: http://www.infoq.com/news/2013/07/Oracle-Removes-getCallerClass
The method getCallerClass is used here in java.util.logging.Logger:
public static Logger More ...getLogger(String name) {
return demandLogger(name, null, Reflection.getCallerClass());
}
This leads to the variable caller to be null in the following code of java.util.logging.Logger:
if (sm != null && !SystemLoggerHelper.disableCallerCheck) {
if (caller.getClassLoader() == null) {
return manager.demandSystemLogger(name, resourceBundleName);
}
}
return manager.demandLogger(name, resourceBundleName, caller);
By setting the systemvariable as explained above, the caller variable will not be used.

The Oracle bug JDK-8145302 NullPointerException at java.util.logging.Logger.demandLogger has been replaced with
JDK-8177325 Caller sensitive methods Logger.getLogger, Logger.getAnonymousLogger, will throw NPE if there is no caller on the stack.
The workaround in that bug report is listed as:
Workaround: use an auxiliary class in order to call Logger.getLogger instead of calling Logger::getLogger directly from JNI.
As you can see from your stacktrace:
java.lang.NullPointerException
at java.util.logging.Logger.demandLogger(Logger.java:451)
at java.util.logging.Logger.getLogger(Logger.java:502)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.mclFeval(Native Method)
...
the com.mathworks.toolbox.javabuilder.internal.MWMCR.mclFeval is a JNI method calling java.util.logging.Logger.getLogger.
Mathworks should update the MWMCR class to include a java helper method to invoke getLogger and that helper method should be called from JNI instead of getLogger directly.

Velocity - NullPointerException

During my searching, I would like to have some help about my problem :
So this is my error, the trace :
VelocityView : Error processing a template for path '/comptes/affilies.html.vtl'
Invocation of method 'getRemunerationVendeur' in class model.User threw exception java.lang.NullPointerException at /comptes/affilies.html.vtl[line 28, column 20]
java.lang.NullPointerException
at model.User.getListRemunerationVendeur(User.java:238)
at model.User.getRemunerationVendeur(User.java:268)
at sun.reflect.GeneratedMethodAccessor75.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.velocity.runtime.parser.node.PropertyExecutor.execute(PropertyExecutor.java:127)
at org.apache.velocity.util.introspection.UberspectImpl$VelGetterImpl.invoke(UberspectImpl.java:523)
at org.apache.velocity.runtime.parser.node.ASTIdentifier.execute(ASTIdentifier.java:198)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:271)
at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:561)
at org.apache.velocity.runtime.directive.VelocimacroProxy.handleArgValues(VelocimacroProxy.java:325)
at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:189)
at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:300)
at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:230)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
at org.apache.velocity.runtime.directive.Foreach.renderBlock(Foreach.java:281)
at org.apache.velocity.runtime.directive.Foreach.render(Foreach.java:258)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
at org.apache.velocity.Template.merge(Template.java:356)
at org.apache.velocity.Template.merge(Template.java:260)
at org.apache.velocity.tools.view.VelocityView.performMerge(VelocityView.java:942)
at org.apache.velocity.tools.view.VelocityView.merge(VelocityView.java:902)
at org.apache.velocity.tools.view.VelocityViewServlet.mergeTemplate(VelocityViewServlet.java:318)
at org.apache.velocity.tools.view.VelocityViewServlet.doRequest(VelocityViewServlet.java:220)
at org.apache.velocity.tools.view.VelocityViewServlet.doGet(VelocityViewServlet.java:182)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:120)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:97)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:109)
at filter.AuthFilter.doRedirect(AuthFilter.java:54)
at velosurf.web.auth.AuthenticationFilter.doFilter(AuthenticationFilter.java:392)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:89)
at filter.DateFilter.doFilter(DateFilter.java:309)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:89)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:156)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:289)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:838)
at com.caucho.network.listen.TcpSocketLink.dispatchRequest(TcpSocketLink.java:1345)
at com.caucho.network.listen.TcpSocketLink.handleRequest(TcpSocketLink.java:1301)
at com.caucho.network.listen.TcpSocketLink.handleRequestsImpl(TcpSocketLink.java:1285)
at com.caucho.network.listen.TcpSocketLink.handleRequests(TcpSocketLink.java:1193)
at com.caucho.network.listen.TcpSocketLink.handleAcceptTaskImpl(TcpSocketLink.java:992)
at com.caucho.network.listen.ConnectionTask.runThread(ConnectionTask.java:117)
at com.caucho.network.listen.ConnectionTask.run(ConnectionTask.java:93)
at com.caucho.network.listen.SocketLinkThreadLauncher.handleTasks(SocketLinkThreadLauncher.java:169)
at com.caucho.network.listen.TcpSocketAcceptThread.run(TcpSocketAcceptThread.java:61)
at com.caucho.env.thread2.ResinThread2.runTasks(ResinThread2.java:173)
at com.caucho.env.thread2.ResinThread2.run(ResinThread2.java:118)
Normally the class User.java works.
This is a piece of my class java (User.java) that corresponds to my error :
Instance service = (Instance)db.get("service_by_code");
vendeur.put("ope_code", operateur.get("ope_code"));
vendeur.put("srv_code", service.get("srv_code"));
My variable service corresponds at a line of a result at my database.
I think my row is NULL in the database (because a nullPointerException is mainly that ... an object set at NULL !) but I don't know to solve the problem in my database : to change value in the row of my database.
I try it but It changes nothing.
Please if you've got a piece of advice.
Ale.

It looks, like your object of class Instance is NULL, because of your work with DB.
Anyway, should be nice, if you give a stacktrace of your exception, so nobody will try to guess.

YUICompressor crashes - stackoverflow error

I frequently get what appears to be a stackoverflow error ;-) from YUICompressor. The following is the first part of thousands of error lines that come from attempting to compress a 24074 byte css stylesheet (not the "Caused by java.lang.StackOverflowError about 8 lines down):
iMac1:src jas$ min ../style2.min.css style2.css
Exception in thread "main" java.lang.reflect.InvocationTargetException
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 com.yahoo.platform.yui.compressor.Bootstrap.main(Bootstrap.java:21)
Caused by: java.lang.StackOverflowError
at java.lang.Character.codePointAt(Character.java:2335)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3344)
at java.util.regex.Pattern$Branch.match(Pattern.java:4114)
... (plus 1021 more error lines)
The errors happen usually after adding a couple of lines to the file getting compressed. The css is fine, and works perfectly in the uncompressed format. I don't see a particular pattern to the types of selectors added to the file that cause the errors. In this case, adding the following selector to a previously compressible file resulted in the errors:
#thisisatest
{
margin-left:87px;
}
I am wondering if there is perhaps a flag to java to enlarge the stack that might help. Or if that is not the problem, what is?
EDIT:
As I was posting this question, it dawned on me that I should check the java command to see if there was a parameter to enlarge the stack. Turns out that it is -Xssn, where "n" is a parameter to indicate the stack size. Its default value is 512k. So I tried 1024k but that still led to the stackoverflow. Trying 2048k works however, and I think this could be the solution.
EDIT 2:
While I no longer use this method for minification any longer, to be more specific here is the full command (which I have set up as a shell alias), showing how the -Xss2048k parameter is used:
java -Xss2048k -jar ~/Documents/RepHunter/Website\ Materials/Code/Third\ Party\ Libraries/YUI\ Compressor/yuicompressor-2.4.8.jar --type css -o

As posted in my edit, the solution was to add the parameters to the java command. The clue was the error line at the 5-th "at" line, as follows:
at com.yahoo.platform.yui.compressor.Bootstrap.main(Bootstrap.java:21)
Caused by: java.lang.StackOverflowError
Seeing that the issue was a "StackOverlowError" ;-) gave the suggestion to try to increase the stack size. The default is 512k. My first try of 1024k did not work. However increasing it to 2048k did work, and I have had no further issues.

Getting weird errors on stack manipulation

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.