在没有CD的OS X Terminal中编译Java代码

Question

When I run

javac 'path/to/test.java'
java 'path/to/test'

I get an error like this

Exception in thread "main" java.lang.NoClassDefFoundError: path/to/test (wrong name: test)

It works when I do the same after I run "cd path/to", but is there a way to do this without the cd command? If so, how?

Answer 1

Your Test.java file should have a package line at the top:

package path.to;

public class Test {

    public static void main(String argv[]) {
    }
}

Then you can compile and run it. It works on my MacBook Pro. Note that java path.to.Test and java path/to/Test are equivalent .

% javac path/to/Test.java
% java path.to.Test

If you are missing the package statement, then you will get the error that you are reporting.

% javac path/to/Test.java
% java path.to.Test
Exception in thread "main" java.lang.NoClassDefFoundError: path/to/Test (wrong name: Test)

Answer 2

If you wish to compile and run the class from your current location (presumably a project directory), I would recommend:

1. Use a package declaration in your class:

    package path.to; public class Test { public static void main(String[] args) { System.out.println("LOADED"); } } 

2. When you run your code do so with dot notation to the class name:

    javac path/to/Test.java java path.to.Test 

Answer 3

Assuming test.java does not have a package statement, your class (which should be named Test , not test ) is in the unnamed package, so do this:

javac 'path/to/test.java'
java -cp 'path/to' test

If your test.java file starts with a package to; statement, then you do this:

java -cp 'path' to.test

And if it says package path.to; , then you do this:

java path.to.test

or this to be explicit:

java -cp . path.to.test

If your package statement says any other name, then your directory structure is wrong, since the directory must match the package statement, starting at the directory named in the classpath ( -cp ).