java: I cannot run the program after compilation? Help me

StackOverflow https://stackoverflow.com/questions/17792214

Question

i just downloaded a java program TableDrivenVaccumAgent.java while i was searching some robot class examples, i have included the requisite jars in the path C:\Program Files\Java\jdk1.7.0_25\jre\lib\ext but i am getting error after it compiles successfully.

what should i need to do more to resolve the following error:

Exception in thread "main" java.lang.NoClassDefFoundError: TableDrivenVacuumAgent (wrong name: aima/core/environment/vacuum/TableDrivenVacuumAgent)
        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)

now error is:

Exception in thread "main" java.lang.NoClassDefFoundError: TableDrivenVaccumAgent (wrong name: aima/core/environment/vacuum/TableDrivenVaccumAgent)
        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)
Was it helpful?

Solution

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:

  1. Class is not available in Java Classpath.

  2. You might be running your program using jar command and class was not defined in manifest file's ClassPath attribute.

  3. Any start-up script is overriding Classpath environment variable.

OTHER TIPS

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.

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