Lesson: Common Problems (and Their Solutions) (The Java™ Tutorials > Getting Started)

Lesson: Common Problems (and Their Solutions) (The Java™ Tutorials > Getting Started): "Exception in thread 'main' java.lang.NoClassDefFoundError: HelloWorldApp/class
A common mistake made by beginner programmers is to try and run the java launcher on the .class file that was created by the compiler. For example, you'll get this error if you try to run your program with java HelloWorldApp.class instead of java HelloWorldApp. Remember, the argument is the name of the class that you want to use, not the filename.
Exception in thread 'main' java.lang.NoSuchMethodError: main
The Java VM requires that the class you execute with it have a main method at which to begin execution of your application. A Closer Look at the 'Hello World!' Application discusses the main method in detail."

Lesson: Common Problems (and Their Solutions) (The Java™ Tutorials > Getting Started)

Lesson: Common Problems (and Their Solutions) (The Java™ Tutorials > Getting Started): "Exception in thread 'main' java.lang.NoClassDefFoundError: HelloWorldApp
If you receive this error, java cannot find your bytecode file, HelloWorldApp.class.
One of the places java tries to find your bytecode file is your current directory. So, for example, if your bytecode file is in /home/jdoe/java, you should change your current directory to that. To change your directory, type the following command at the prompt and press Return:
cd /home/jdoe/java

If you enter pwd at the prompt, you should see /home/jdoe/java. If you enter ls at the prompt, you should see your .java and .class files. Now enter java HelloWorldApp again.
If you still have problems, you might have to change your CLASSPATH environment variable. To see if this is necessary, try clobbering the classpath with the following command.
unset CLASSPATH

Now enter java HelloWorldApp again. If the program works now, you'll have to change your CLASSPATH variable in the same manner as the PATH variable above."

Lesson: Common Problems (and Their Solutions) (The Java™ Tutorials > Getting Started)

Lesson: Common Problems (and Their Solutions) (The Java™ Tutorials > Getting Started): "Error Messages on UNIX Systems
Exception in thread 'main' java.lang.NoClassDefFoundError: HelloWorldApp
If you receive this error, java cannot find your bytecode file, HelloWorldApp.class.
One of the places java tries to find your bytecode file is your current directory. So, for example, if your bytecode file is in /home/jdoe/java, you should change your current directory to that. To change your directory, type the following command at the prompt and press Return:
cd /home/jdoe/java

If you enter pwd at the prompt, you should see /home/jdoe/java. If you enter ls at the prompt, you should see your .java and .class files. Now enter java HelloWorldApp again.
If you still have problems, you might have to change your CLASSPATH environment variable. To see if this is necessary, try clobbering the classpath with the following command.
unset CLASSPATH

Now enter java HelloWorldApp again. If the program works now, you'll have to change your CLASSPATH variable in the same manner as the PATH variable above.
Exception in thread 'main' java.lang.NoClassDefFoundError: HelloWorldApp/class
A common mistake made by beginner programmers is to try and run the java launcher on the .class file that was created by the compiler. For example, you'll get this error if you try to run your program with java HelloWorldApp.class instead of java HelloWorldApp. Remember, the argument is the name of the class that you want to use, not the filename.
Exception in thread 'main' java.lang.NoSuchMethodError: main
The Java VM requires that the class you execute with it have a main method at which to begin execution of your application. A Closer Look at the"

Another Java Error Found

java.security.policy: error parsing file:/C:/apps/java/servers/tomcat60/conf/catalina.policy:

line 43: expected [;], found [/]

java.lang.NoClassDefFoundError: org/apache/juli/logging/LogFactory

When i try to start tomcat the following exception happens:

java.lang.NoClassDefFoundError: org/apache/juli/logging/LogFactory
at org.apache.catalina.startup.Bootstrap.(Bootstrap.java:53)
Exception in thread "main"

Why ?

....

Java Exceptions

I think this blog will be very usefull for java programmers.

I don't know, but i think in the world will happen more than 1.000.000 exceptions by hour.

So i invite every java programmer to type here every exception found



I think it will be very interesting thing.



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But What is a Java Exception ?

An exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions.



The most important exceptions issues:



How to catch and handle exceptions

The discussion includes the try, catch, and finally blocks, as well as chained exceptions and logging.



How to Throw Exceptions ?

Using the throw statement and the Throwable class and its subclasses.



Unchecked Exceptions

The correct and incorrect use of the unchecked exceptions indicated by subclasses of RuntimeException.



Advantages of Exceptions

The use of exceptions to manage errors has some advantages over traditional error-management techniques.