Thread: package for Beginners

Respected PROGRAMMERS

When a classfile that belongs to a package, then

package PackageName;


is included in the source code of that file. So when jvm is invoked by writing

java PackageName.classfilename

it gets executed.

Is it that "package PackageName" guarantees the jvm that this classfile belongs to this very package? Because if we omit the "package PackageName" statement, then jvm still finds out the class file but gives

Exception in thread "main" java.lang.NoClassDefFoundError: Classfilename
wrongname PackageName/ClassfileName
It means jvm finds out the file but there is some reason for which it considers that this classfile has a wrong name.

As far as i know, you have to fix the environment variables, in order to let jvm know about the exact location of your file. Coz your class file is not set as a main project file. And in your environment variable CLASS_PATH, you have given the path to the directory. So, it is able to find the package but not class.
Also, you can use editors. Editors allow you to set any project as main project.
I don't know, if this is the answer, you asking for.

Once the JVM finds the class you are looking for, it checks the first line for that package statement. If the package statement isn't there, it assumes the class, the command or SOMETHING was named incorrectly. The package statement is absolutely required in a source file to to make sure both the compiler and the JVM at runtime understand what classes should be where.

This has nothing to do with Class Path if I understand your question correctly...