I'm using the JDK 3.1. I am using XML Publisher. I'm getting this error:
Could not find the main class. Program will exit.
After I click on "OK", I get
Java execution failed. Please check the Java Option in the option dialog
Sounds like you're trying to execute .jar file and there's no Main-Class entry in the manifest file. Other than that obvious point, your question does not give much information for assistance.
Your question is tricky to understand, but I'm guessing that you haven't actually compiled your Java code, or your compiled code isn't on the classpath.
When I try and execute a non-existent class (this would work if there was a MyClass.class on the classpath with a main() method):
paul#paul-laptop:~$ java MyClass
Exception in thread "main" java.lang.NoClassDefFoundError: MyClass
Caused by: java.lang.ClassNotFoundException: MyClass
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
Could not find the main class: MyClass. Program will exit.
Is that what you're seeing? If so:
compile your class with javac if you haven't done so
check that your classpath includes the location of the class
(You can specify the classpath explicitly when you execute the java program using -classpath, check the documentation for details.)
I include this answer as someone who has made an error someone consuming java rather than programming in it would make:
On the command line when executing a JAR file, be sure your line reads
java -jar whatever.jar
instead of
java whatever.jar
Without the -jar you sometimes get the "Could not find the main class" error.
Here are some good answers What does "Could not find or load main class" mean?
But, I will share one possibility I had. I used the JDK1.7 to compile my code and run the jar package using the JDK1.6, the error is:
Could not find the main class. Program will exit.
So, check if the JDK version you used to run your code is lower than that used to compile your code.
Check this website: "Could not find main class" error when previewing BI Publisher for Word. It directly references Java issues with Oracle BI Publisher Plugins for Word.
It basically says that you need to set your Java Home by going to Options in the BI Publisher Tab in the MS Office Ribbon.
Related
Following this post, I am using the following steps to compile the parser/lexer from this repository:
export CLASSPATH=".:/usr/local/Cellar/antlr/<version>/antlr-<version>-complete.jar:$CLASSPATH"
antlr <grammarName>.g4 -o <someFolder>/
javac <someFolder>/<grammarName>*.java
but when I use the instructions here:
grun <someFolder>/<grammarName> tokens -tokens < <inputFile>
I get this error messages:
Exception in thread "main" java.lang.NoClassDefFoundError: IllegalName: <someFolder>/<grammarName>Lexer
at java.base/java.lang.ClassLoader.preDefineClass(ClassLoader.java:889)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1014)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:825)
at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:723)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:646)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:604)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:168)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
at org.antlr.v4.gui.TestRig.process(TestRig.java:129)
at org.antlr.v4.gui.TestRig.main(TestRig.java:119)
I would appreciate if you could help me know what is the problem and how I can resolve it.
I don’t see where you’ve specified a package name, so now your Java classes are located in <someFolder>. Be sure to compile them in that folder.
Then you’ll need to add that folder to your classpath (probably instead of “.”)
Try adding <someFolder> into the CLASSPATH you’re exporting. Then leave it off of your grun command line.
Java will only load classes from the Classpath (it’s a security thing). When TestRig runs, it attempts to load your class by building the Java class name it would have produced for you Parser (and Java will have to find that class somewhere in the classpath).
Your could modify the grun alias to allow for you to specify a directory to search for your classes, and use the -cp option on the Java command, but that’s probably more trouble than just adding it to you classpath that you’re using for this testing.
When I try to execute the following program from DOS I get the results below..
The following program is in C:\Users\Apostolos\Documents\NetBeansProjects\Java1\src\java1
package java1;
public class MyProgram{
public static void main(String[] args){
System.out.println("Rome wasn’t burned in a day!");
}
}
javac MyProgram.java
works fine
But java MyProgram gives the following:
Exception in thread "main" java.lang.NoClassDefFoundError: MyProgram (wrong name
: java1/MyProgram)
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)
................
Why this is happening??
My environment variables:
CLASSPATH: .;C:\Program Files (x86)\Java\jre7\lib\ext\QTJava.zip;C:\Program Files\Java\jdk1.7.0_05\bin
PATH: C:\Program Files\Java\jdk1.7.0_05\bin
JAVA_HOME: C:\Program Files\Java\jdk1.7.0_05
I have seen similar problems here but i cannot find the solution to my problem.
Thank you in advance!
This is caused when there is a class file that your code depends on and it is present at compile time but not found at runtime. Look for differences in your build time and runtime classpaths.
Refer this Link
2 points you should keep in mind when using java tool:
Add the class to the classpath.
Use the fully qualified name of the class to be run.
Hence:
java -cp C:\Users\Apostolos\Documents\NetBeansProjects\Java1\bin java1.MyProgram
assuming the following file exists after compilation:
C:\Users\Apostolos\Documents\NetBeansProjects\Java1\bin\java1\MyProgram.class
For more info, see:
Mastering the Java CLASSPATH.
"Setting the class path" Documentation.
NoClassDefFoundError in Java comes when Java Virtual Machine is not
able to find a particular class at runtime which was available during
compile time. For example if we have a method call from a class or
accessing any static member of a Class and that class is not available
during run-time then JVM will throw NoClassDefFoundError.
Obvious reason of NoClassDefFoundError is that a particular class is not available in Classpath, so we need to add that into Classpath or we need to check why it’s not available in Classpath if we are expecting it to be. There could be multiple reasons like:
Class is not available in Java Classpath.
You might be running your program using jar command and class was
not defined in manifest file's ClassPath attribute.
Any start-up script is overriding Classpath environment variable.
Try in this way
run command prompt as Administrator, and
cd C:\Users\Apostolos\Documents\NetBeansProjects\Java1\src
then
javac java1/MyProgram.java
Then
java java1.MyProgram
This will work.
Exception in thread "main" java.lang.NoClassDefFoundError: MyProgram (wrong name
This exception is thrown when the JVM cannot finf your class at run time
From C:\Users\Apostolos\Documents\NetBeansProjects\Java1\src
execute " "java java1.MyProgram" –
I am running my java program but on executing it gives me following error.
before it was running fine but now it's throwing following error.
I checked my class path, path in environment variable all are correct.
Exception in thread "main" java.lang.UnsatisfiedLinkError: java.util.zip.ZipFile
.open(Ljava/lang/String;IJ)J
at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.<init>(ZipFile.java:114)
at java.util.jar.JarFile.<init>(JarFile.java:135)
at java.util.jar.JarFile.<init>(JarFile.java:72)
at sun.misc.URLClassPath$JarLoader.getJarFile(URLClassPath.java:646)
at sun.misc.URLClassPath$JarLoader.access$600(URLClassPath.java:540)
at sun.misc.URLClassPath$JarLoader$1.run(URLClassPath.java:607)
at java.security.AccessController.doPrivileged(Native Method)
at sun.misc.URLClassPath$JarLoader.ensureOpen(URLClassPath.java:599)
at sun.misc.URLClassPath$JarLoader.<init>(URLClassPath.java:583)
at sun.misc.URLClassPath$3.run(URLClassPath.java:333)
at java.security.AccessController.doPrivileged(Native Method)
at sun.misc.URLClassPath.getLoader(URLClassPath.java:322)
at sun.misc.URLClassPath.getLoader(URLClassPath.java:299)
at sun.misc.URLClassPath.getResource(URLClassPath.java:168)
at java.net.URLClassLoader$1.run(URLClassLoader.java:194)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: com.sun.tools.javac.Main. Program will exit.
To elaborate on #Peter Lawrey's answer ...
The start of the stacktrace is this:
Exception in thread "main" java.lang.UnsatisfiedLinkError: java.util.zip.ZipFile
.open(Ljava/lang/String;IJ)J
at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.<init>(ZipFile.java:114)
...
The UnsatisfiedLinkError is thrown when you attempt to call a native method that has not been resolved to a method in the corresponding native library. The rest of the message tells us that the method at fault has the signature:
long java.util.zip.ZipFile.open(String, int, long)
and that meshes with the top frame of the stack trace ... and the fact that Java's ZipFile code is known to use a native library for the heavy lifting.
The fact that it has gotten this far means that the JVM has found the native library and loaded it. But apparently, the load didn't resolve this overload of the native open method. That can only mean one thing: that the version of the ZipFile class on the bootclasspath does not match the native library.
We cannot make any definite conclusions about whether this is a JDK or a JRE, but it seems likely that it is a JDK ... unless the OP is trying to call the Java compiler in a strange way. (The "could not find the main class: com.sun.tools.javac.Main" message probably means that the JVM could not load the class ... because of the UnsatisfiedLinkError breakage.)
Either way, JDK versus JRE is not the immediate problem. The real problem is a mismatch between the "rt.jar" on the JVM's bootclasspath, and the native libraries.
The question asks:
how to solve this then?
It depends on what exactly you did to get this error.
What command did you run?
What were the command line options and arguments?
Have you been "messing around" with your JRE / JDK installation?
Are you trying to use the "rt.jar" file from one installation in another one?
It means your rt.jar is for a different version of Java as your JVM.
I would ensure that you don't have a rt.jar in your boot class path and your JRE is installed correctly.
Could not find the main class: com.sun.tools.javac.Main. Program will exit.
When a class fails to load due to some low level error, it reports that the class could not be found.
The reference in the error message about not finding com.sun.tools.javac.Main leads me to believe that this is a program that needs to be run with the JDK rather than just a JRE.
your JRE path is pointing to the JDK path
Solution :
Step 1: Right click the server
Step 2: Click the Run Time Configuration
Step 3: GIVE the JRE path under the JDK.
Solution fixed
I just restarted java for university and I have a pretty basic program that I need to code. The thing is every time I try to run it, I get a NoClassDefFoundError as follow:
run:
java.lang.NoClassDefFoundError: log120/devoir1/LOG120Devoir1
Caused by: java.lang.ClassNotFoundException: log120.devoir1.LOG120Devoir1
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: log120.devoir1.LOG120Devoir1. Program will exit.
Exception in thread "main" Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)
I am using Netbeans 7.0.1 since it was the IDE I was using a couple of years ago to code java. I googled the error and found something about the class path but all the example I found were for LINUX based OS so I am kinda lost as to how to set it right on Windows.
The class does exist, the program did compile, from what I understand this error comes when the JVM tries to run the code and does not find the class.
Anyone can help me with finding the ClassPath on Netbeans 7.0.1 or if it is not the ClassPath finding why this error keeps popping up?
If you're trying to run your own code, setting your classpath is probably barking up the wrong tree. Netbeans should be including your code automatically on the classpath when it tries to run it.
Please describe how you have your code laid out within your project (eg do you have LOG120Devoir1.java in a log120/devoir1 directory?) as well as how you told netbeans that you wanted to run that class as your main method.
I have been trying for what seems like two days now to get my java application to compile from the command line in Ubuntu. I know I have Java installed because I can run my applications in Eclipse & Netbeans and they work fine. But if I want to compile my applications from the command line I get the following error message:
javac Main.java
Everythings fine, no errors or anything. Then I try:
java Main
And I get this error message:
Exception in thread "main" java.lang.NoClassDefFoundError: Main (wrong name: input/Main)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:637)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:336)
Could not find the main class: Main. Program will exit.
Try:
java input.Main
By the looks of your error, your Main class is in package "input". You need to specify package name when running a class, not the filename.
Open terminal and paste this command:
export CLASSPATH=.:/usr/local/tomcat/common/lib/jsp-api.jar:/usr/local/tomcat/common/lib/servlet-api.jar:/home/trenog/javokapi/bin/xmlrpc.jar
This looks like a classic Classpath problem. Eclipse and Netbeans will set up the classpath for you, but when you're writing to the command line, you're on your own.
Assuming you're using BASH, try typing the following into the command line:
CLASSPATH=/path/to/your/java/class/file
Or, alternately, you can do this from the java command line:
java -cp /path/to/your/java/class/file Main
Follow this link for more info.
EDIT: Well, I see you figured it out. Congrats.
The classloader simply can't find the class input.Main.
The class should be located in the directory ./input, the file inside that directory should be called Main.class and the java command should be 'java input.Main'.