I have a Java Project (an application to play connect 4) and I want to turn it into an executable file. I created this project in VsCode, and I am using the Java Language Server (see details below). I extracted the .jar file, and used Launch4J to turn it into an executable, and when I run it, I get an error message (see below).
I researched the problem, and it seems that I need to compile my code targeting Java SE 8 rather than 17 (I have 17 currently installed). Could anyone explain to me how I should do this, or is there anything else I'm doing wrong?
The project has multiple files. I'm not sure if this is relevant, but the project has no external dependencies, although it does use javax.swing, javax.sound, and java.awt (as well as java.io.File, java.io.IOException, and java.util.Random, but I'm pretty sure those are irrelevant).
I have eclipse installed if it's necessary, but I only installed it today, and have no experience using it at all. The JDK I am using is (I believe) version 1.8.0_321. (At least this is what I get when I type in java -version.)
The Java compiler version is javac 17.0.2
When I try to run the executable generated by Launch4J, I this is the error I get:
Exception in thread "main" java.lang.UnsupportedClassVersionError: Main has been compiled by a more recent version of the Java Runtime (class file version 61.65535), this version of the Java Runtime only recognizes class file versions up to 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
And the popup error:
Java Virtual Machine Launcher
Error: A JNI error has occurred, please check your installation and try again.
Here are the Settings I used in Launch4J:
Output File: C:\Users\username\OneDrive\Coding\Java Connect 4 v.2\Connect 4.exe
Jar: C:\Users\username\OneDrive\Coding\Java\Java Connect 4 v.2\Java Connect 4 v.2.jar
Don't wrap the jar, launch only: NOT ticked
Wrapper Manifest: none
Change dir: .
Command Line args: none
Process priority: Normal
Both Options NOT ticked
Min JRE version: 1.2.0, Prefer public JRE, but use JDK runtime if newer
Max JRE version: none, First 64-bit, then 32-bit. (This was the default.)
All other settings are default.
Download the latest Java JDK version as .exe file (“x64 Installer”) and install by clicking on the .jar file.
Now the server should start again
#Holger has answered this question. The answer to the problem was to ship a custom JRE image with the application with the help of JLink. That way it can be used regardless of the local version of JRE.
Related
Since upgrading to install4j 7.0.5 and Java 10, users that run our application on Windows more and more often report that the application throws
java.lang.NoSuchMethodError: <init>
at javafx.graphics/com.sun.glass.ui.win.WinApplication.staticScreen_getScreens(Native Method)
at javafx.graphics/com.sun.glass.ui.Screen.initScreens(Unknown Source)
at javafx.graphics/com.sun.glass.ui.Application.lambda$run$1(Unknown Source)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
UiLauncher (WAITING)
at java.base#10.0.1/jdk.internal.misc.Unsafe.park(Native Method)
at java.base#10.0.1/java.util.concurrent.locks.LockSupport.park(Unknown Source)
at java.base#10.0.1/java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(Unknown Source)
at java.base#10.0.1/java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(Unknown Source)
at java.base#10.0.1/java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(Unknown Source)
at java.base#10.0.1/java.util.concurrent.CountDownLatch.await(Unknown Source)
at platform/javafx.graphics#10.0.1/com.sun.javafx.tk.quantum.QuantumToolkit.startup(Unknown Source)
at platform/javafx.graphics#10.0.1/com.sun.javafx.application.PlatformImpl.startup(Unknown Source)
at platform/javafx.graphics#10.0.1/com.sun.javafx.application.PlatformImpl.startup(Unknown Source)
at platform/javafx.swing#10.0.1/javafx.embed.swing.JFXPanel.initFx(Unknown Source)
at platform/javafx.swing#10.0.1/javafx.embed.swing.JFXPanel.<init>(Unknown Source)
at java.base#10.0.1/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base#10.0.1/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at java.base#10.0.1/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.base#10.0.1/java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.base#10.0.1/java.lang.Class.newInstance(Unknown Source)
at app//...
when starting the application though the install4j created exe file. The error is triggered by creating an instance of javafx.embed.swing.JFXPanel through reflection:
Class.forName("javafx.embed.swing.JFXPanel").newInstance();
We currently suspect that for some reason an incompatible DLL is loaded (glass.dll seems to contain the native method mentioned in the stacktrace).
Does anyone know how to prevent this error? E.g. is there are way to restrict the java.library.path used when executing the application through the install4j-generated exe to the Java runtime environment that was embedded in the installer and installed locally with the application?
According to one user, the error does not occur if the application is started "manually" using the
java -jar app.jar
command. So it seems the problem lies with the install4j created executable.
The workaround to this problem seems to be to remove all occurences of "glass.dll" from your system %PATH%.
I believe a fix must be implemented somewhere else, though; either in the Java runtime or in the Install4j code, but cannot be implemented in the Java code of the actual app:
For some reason the Java runtime version in Install4j checks the bundled JRE last when locating the libraries. In this case the problematic native library is glass.dll which should contain the requested <init> method but if anywhere in your %PATH% there is an older, incompatible version of glass.dll (e.g. from a previous Java 8 installation) that file will be loaded with a higher precedence and then the application will crash natively.
This is not a problem in the code of the application (the java code), nor a problem with the bundled JDK, this is a problem of how the install-4j-generated exe files (or maybe Java internally) tries to resolve native dlls. Instead of checking all path elements first, it should be checking the bundled JRE directory, first.
With Procmon you can see that it loads arbitrarily placed glass.dll files in the path, first: I added one from JDK 1.8 into one of my path elements and got this (plus the crash):
I have been trying to fix this problem for several hours now, and I am totally at my wits end.
My old computer crashed, but luckily I was able to recover most of my files. I installed eclipse on my desktop, and attempted to import a few projects into eclipse. Every one of them had problems, and not a single one will run. I am running Windows 7 on a homebuild PC- I am 99% sure this is not a hardware problem, I don't think you need specs.
First, every time I import I have followed this thread because it is the first of my problems: every time I import a project, eclipse will not recognize anything from java and I apparently need to manually tell it what to use (which is annoying, and if anyone has a fix for this it would be great to know how to stop it).
But the big problem comes after I fix that. Whenever I try to run the project, no matter which project it is I get the error I copied in the description:
Exception in thread "main" java.lang.UnsupportedClassVersionError: MainMethod : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
I have tried just about everything, and am getting pretty close to just breaking the whole thing. I have followed all of the following guides: this one, this one and this one. All of them say to do the same thing: change the project preferences and check the compiler settings. The settings should match.
I am running JDK7 and JRE7. JRE8/JDK8 is not installed anywhere on my desktop- I am not sure why eclipse seems to think it is. My question is this: how do I fix this problem? Do I need to do a clean install and follow a specific set of steps to stop this from happening? Do I need to put JDK8 on my computer? Do I need ro re-import the projects into the workspace in a specific way? Am I just stuck?
If you have followed the steps of configuring JDK, the project might be referring to previously generated classes. You may try Project on menu > Clean, select all projects and then try to run the application.
Moreover, go to Project Properties, Java Build Path, Libraries and confirm that you are referring to the correct Java Runtime version.
Your project was created with a version of Java JDK, but your eclipse has a older version of JDK.
Verify if the version of your project's JDK is the same of the eclipse's JDK.
First off. I am a newbie and green with respect to Java programming.
I created a Java Eclipse "SWT" "Application Window" on a Eclipse Kepler 4.3.1 (32-bit) running WindowBuilder and SWT (swt.jar). The design view is a composite.
The java application runs fine from Eclipse. I simply press the play button and presto.
Problem:
Issuing
java -cp . PkgNetAccelerator32.netAcceleratorApp
yields the following error message:
Exception in thread "main" java.lang.NoClassDefFoundError: org/eclipse/swt/widgets/Composite
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.getMethod0(Unknown Source)
at java.lang.Class.getMethod(Unknown Source)
at sun.launcher.LauncherHelper.getMainMethod(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.eclipse.swt.widgets.Composite
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 6 more
I was doing some research and several posts on other issues suggested that the cure is to create a manifest. I saw an article that said something like:
Select the src folder, right click and select export, then Java, then JAR file, specify Manifest.jar and a path on the folder, make sure the "Generate the manifest file" is selected, and press finish.
I created the manifest file and tried launching it with the following command line:
java -jar ../Manifest.jar -cp . PkgNetAccelerator32.netAcceleratorApp
That yielded the same error message above.
I saw another article that said that one should add in the swt.jar file, but that is taken care of by the manifest. No? Specifying "swt.jar" instead of the manifest that I created resulted in an error message:
no main manifest attribute, in ../swt.jar
That error message makes sense.
I am at a loss. How do I run the java application?
I am testing on my Windows 7 Professional 64-bit desktop, but I need to run on CENTOS too. That should be no problem, as I assume whatever the fix on Windows is, will work on CENTOS.
UPDATE:
I placed the two lib files in a /lib folder to match the answer given. I then issued the following command line and got the following error message.
C:\SoftDev\Projects\NetAccelerator\JavaWorkspace\NetAccelerator32>java -cp "bin/*;lib/*" PkgNetAccelerator32.netAcceleratorApp
Exception in thread "main" java.lang.UnsatisfiedLinkError: Cannot load 32-bit SWT libraries on 64-bit JVM
at org.eclipse.swt.internal.Library.loadLibrary(Unknown Source)
at org.eclipse.swt.internal.Library.loadLibrary(Unknown Source)
at org.eclipse.swt.internal.C.<clinit>(Unknown Source)
at org.eclipse.swt.widgets.Display.<clinit>(Unknown Source)
at PkgNetAccelerator32.netAcceleratorApp.open(netAcceleratorApp.java:43)
at PkgNetAccelerator32.netAcceleratorApp.main(netAcceleratorApp.java:33)
I found the following article, which produces a command line that works, just that is not reasonable for sending. I much rather use the answer.
Lets assume you have a eclipse project structure similar to this:
Workspace
-> Project
-> src (source code directory)
-> bin (compiled byte code directory as JAR)
-> lib (jar directory)
-> .classpath (eclipse file)
-> .project (eclipse file)
I am assuming that you are exporting the JAR as an executable JAR.
So in order to run a class in that exported JAR with another JAR from the lib directory (swt.jar) while your working directory is the Project directory you will need to execute:
java -cp "bin/*:lib/*" PkgNetAccelerator32.netAcceleratorApp
Using wildcards requires Java 6 or later
Please note: CENTOS requires : as a path separator. Windows uses a semi-colon.
This will add your classes and the swt classes onto the classpath and run your main class PkgNetAccelerator32.netAcceleratorApp
SWT 32bit vs 64bit
You will either need to use a 32bit JVM locally or continue to use a 64bit JVM and use the 64bit version of swt; see swt on windows 64 bit. I would suggest you match your version of your local JVM (32bit or 64bit) with the version that you will be running on the CENTOS machine. You will however need a different swt jar for CENTOS.
I followed some online tutorial and build a little GUI. I tried to make a jar file by clean and build project in the Netbeans, but the jar file doesn't let me open for some reason. Am i missing other stuff?
okay here is what happens after i type in java -jar GUI2.jar
Exception in thread "main" java.lang.UnsupportedClassVersionError: gui2/GUI2 : U nsupported major.minor version 51.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(Unknown Source) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source)at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$000(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) Could not find the main class: gui2.GUI2. Program will exit
If you want to execute a JAR file, you can run from command line "java -jar yourJarFilePathHere".
Also, take a look at this SO post...
https://stackoverflow.com/a/5258323/1246574
Unsupported major.minor version 51.0
This tells that runtime environment doesn't support the format of class compiled
Either upgrade JRE to supported version or compile your source with runtime environment compatibility by adding -source switch
For netbeans: right click on project > properties > source select the source version compatible with your runtime version (java -version from terminal where you are running it) and rebuild the jar
The problem is that when you compile a java file it targets a certain version of Java (1.6, 1.7, etc). So if you compile your project for version 1.7, but on your computer you only have installed 1.6, it will give you this Unsupported major.minor version error when you try to run it. That just means there's a mismatch between the target version and the installed version.
The solution: check the Java version currently installed on your computer with java -version from the command line. I would just go ahead and update to be safe. Then check the target in your Netbeans settings (right click your project name -> Properties -> Sources -> Source/Binary format)
When I run start.jar I get the following error:
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/eclipse/
jetty/start/Main : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: org.eclipse.jetty.start.Main. Program will exit.
According to the Jetty documentation (http://www.eclipse.org/jetty/documentation/current/quickstart-running-jetty.html), all I need to do is download the zip, extract, and run start.jar. Google doesn't seem to provide me with any people having similar issues.
Thanks,
Sam
Take a look on the following discussion and specifically on the most popular answer.
Shortly you have a problem of class version incompatibility. Your jetty is compiled with compiler of java 7 while you are trying to run it with JVM of previous version. The solution is: go forward to Java 7: upgrade your JDK and configure eclipse to use java 7 and start enjoying the new features.
This could happen when you have some code compiled using higher JDK, try to check the JDKs used to compile your code.
Besides according to the documetnation Jetty 9 needs JVM 1.7.
Further links:
What Version Do I Use? (Jetty Documentation)
https://code.google.com/p/googleappengine/issues/detail?id=6768
Unsupported major.minor version 51.0 but everything is set to JDK 1.6
The newest release of Jetty needs Version 1.7 of the JVM. Update your JVM or use an older version of Jetty (not recommended).
You can see the Jetty-versions here: http://www.eclipse.org/jetty/documentation/9.0.2.v20130417/what-jetty-version.html#d0e75
java.lang.UnsupportedClassVersionError happens because of a higher JDK during compile time and lower JRE during runtime.
So upgred your JRE to the version of compiled time version of JDK.
The Java compiler is an advanced version, and the virtual machine is not. Make it uniform either by upgrading your JVM or downgrading your compiler (JDK). I recommend the second option. Gook luck !!!!
This can also happend if you are configuring for example Jetty 8.1 server, but your Jetty installation directory is higher than that, for example 9.1.
So download proper Jetty installation, in Eclipse go to Windows -> Preferences -> Servers -> Jetty -> Edit -> browse to your newly downloaded installation directory.