Temat: Błąd java przy programie Install Shield Wizard
Daniel M.:
Krzysztof S.:
Nie wiem co prawda co to jest "QNX neutrino momentics" ale błąd mówi o tym ze nie znajduje jakiś klas javovych na classpathie. Zgaduje że gdzieś tam są jakieś pliczki .jar które po dodaniu do classpatha powinny załatwić problem.
NoClassDefFoundError to nie ClassNotFoundException i występuje m.in w przypadku obecności kilku jar-ów ale w innych wersjach w classpath.
Tutaj znalazłem całkiem spoko opis - w sumie dość ciekawie napisane:
http://javarevisited.blogspot.com/2011/06/noclassdeffo...
"[...] What is reason of NoClassDefFoundError in Java?
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. It’s important to understand that this is different than ClassNotFoundException which comes while trying to load a class at run-time only and name was provided during runtime not on compile time. Many Java developer mingle this two Error and gets confused.
In short NoClassDefFoundError will come if a class was present during compile time but not available in java classpath during runtime. Normally you will see below line in log when you get NoClassDefFoundError:
Exception in thread "main" java.lang.NoClassDefFoundError
Exception in thread “main” simply indicate that its “main” thread which is not able to find a particular class it could be any thread so just don’t worry . Difference between this error coming in main thread and other thread is , when Exception in thread “main” comes program crashes or shut it self down as opposed to other thread in which case your program will continue to run.,
Difference between java.lang.NoClassDefFoundError and ClassNotFoundException in Java
Many a times we confused ourselves with java.lang.ClassNotFoundException and java.lang.NoClassDefFoundError, though both of them related to Java Classpath they are completely different to each other. ClassNotFoundException comes when JVM tries to load a class at runtime dynamically means you give the name of class at runtime and then JVM tries to load it and if that class is not found in classpath it throws java.lang.ClassNotFoundException. While in case of NoClassDefFoundError the problematic class was present during Compile time and that's why program was successfully compile but not available during runtime by any reason. NoClassDefFoundError is easier to solve than ClassNotFoundException in my opinion because here we know that Class was present during build time but it totally depends upon environment, if you are working in J2EE environment than you can get NoClassDefFoundError even if class is present because it may not be visible to corresponding ClassLoader. [...][...]
How to resolve java.lang.NoClassDefFoundError:
java.lang.NoClassDefFoundError in Java solution 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.
4) Because NoClassDefFoundError is a sub class of java.lang.LinkageError it can also come if one of it dependency like native library may not available.
4) Check for java.lang.ExceptionInInitializerError in your log file. NoClassDefFoundError due to failure of static initialization is quite common.
5) If you are working in J2EE environment than visibility of Class among multiple Classloaders can also cause java.lang.NoClassDefFoundError, see examples and scenario section for detailed discussion.
[...]"
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