线程“ main”中的异常java.lang.NoClassDefFoundError：设置PATh和CLASSPATH之后

Question

I have tried to write a program where i want to access class in a jar.

I am using netbeans as ide,Windows 7 os and have added jar in the libraries. But i keep getting the error.

Exception in thread “main” java.lang.NoClassDefFoundError:after setting PATh and CLASSPATH



I have set the PATh variable to my <jdk directory>/bin;
CLASSPATH to %CLASSPATH%;
and JAVA_HOME to <jdk directory>

<jdk directory> =C:\Program Files\Java\jdk1.7.2

Answer 1

You've just learned an important lesson: Java ignores CLASSPATH environment variable.

You need the PATH to your JAVA/bin for your own convenience, but the CLASSPATH is not useful. I don't have one on any machine I work with.

You can see why: they're so idiosyncratic and specific to a given project.

You should learn how to set it using -cp option on javac.exe and java.exe. You can use Ant to build for more complex projects. And if you deploy to a Java EE app server, you need to understand the classloader hierarchy.

If you insist on using NetBeans, I'd recommend looking in the help to see how it wants you to set CLASSPATH.

Answer 2

You should have the jar file in your classpath to access the classes inside it. Moreover when you run a program from an IDE it overrides any classpath settings you do at system level. Please check your build path in the IDE.