Java Exception - NoDefClassFoundError

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In summary, the conversation is about someone trying to run a Java program they coded using Geany, but encountering an error message stating that a class named temp is missing. The person suspects it may be a coding issue, but even when using example codes from Wikipedia, they still get the same error. They are advised to follow the specific instructions in the system documentation and set up environment variables before attempting to run the program.
  • #1
rollcast
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I'm trying to run a java program I coded using geany but it would let me run it as it comes up with the following error message.

Code:
Exception in thread "main" java.lang.NoClassDefFoundError: temp
Caused by: java.lang.ClassNotFoundException: temp
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: temp. Program will exit.

So then I thought it may have been my bad coding but even when I copied a few example codes from wikipedia it still gave me the same error?

Thanks
A.
 
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  • #2
It looks like you are missing a definition for a class named temp.
 
  • #3
Java is different from most programming languages in that it is VERY fussy about what you call your program files, and the directory structure you put them in.

There should be a "hello world" type of example in the system documentation. Try that, and make sure you do EXACTLY what it tells you to do.

You might have to set up some environment variables (CLASSPATH, in particular) before anything works.
 

Related to Java Exception - NoDefClassFoundError

1. What is a NoDefClassFoundError in Java?

A NoDefClassFoundError in Java is an exception that occurs when the Java Virtual Machine (JVM) is unable to find a particular class at runtime. This can happen for various reasons, such as a missing or incorrect classpath, or a class that was present during compile time but is not available during runtime.

2. How is a NoDefClassFoundError different from a ClassNotFoundException?

A NoDefClassFoundError is a subclass of the ClassNotFoundException. While a ClassNotFoundException occurs when a class is not found during compilation, a NoDefClassFoundError occurs when a class is not found during runtime. Additionally, a NoDefClassFoundError is typically caused by an issue with the classpath or a missing external library.

3. How can I troubleshoot a NoDefClassFoundError in Java?

To troubleshoot a NoDefClassFoundError, you can start by checking your classpath to ensure that all necessary classes and external libraries are included. You can also try recompiling your code to make sure all classes are available at runtime. If the error persists, you may need to check for any missing dependencies or consult with other developers for help.

4. Can a NoDefClassFoundError be fixed?

Yes, a NoDefClassFoundError can be fixed. As mentioned earlier, this error is typically caused by an issue with the classpath or a missing external library. By identifying and addressing the root cause, such as adding the missing class or updating the classpath, the error can be resolved.

5. Is there a way to prevent a NoDefClassFoundError from occurring?

Yes, there are several ways to prevent a NoDefClassFoundError from occurring. One way is to ensure that all necessary classes and external libraries are included in the classpath. Additionally, it is important to regularly check for and update any outdated dependencies. Proper testing and debugging can also help identify and address any potential issues that may lead to a NoDefClassFoundError.

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