Question about javac and java commands

[Travis Roberts]

All:

I noticed something regarding the java command that I wanted to ask about. I created a temp folder on the root of C:\ then I created two more folders called packagea and packageb. In those folders were java files called ClassA and ClassB respectively. I compiled them by running javac packagea/ClassA.java packageb/ClassB.java

So then I tested to make sure it worked by running java packageb.Classb - which is where I coded the main method - and it worked. OK, good so far.

But then..

I changed my working directory to C:\temp\packageb and then attempted to run java ClassB and that does not work. I get:

Error: Could not find or load main class ClassB

Could anyone explain what is happening here?

[Knute Snortum]

I would need to see the code to be sure, but you probably have a package statement at the beginning of your program. That means you have to run the program from the "root" of the project or else Java can't find the class.

[Travis Roberts]

ClassB

package packageb;
import packagea.ClassA;

public class ClassB{
	public static void main(String[] args){
		ClassA a;
		System.out.println("Got it!");
	}
}

ClassA

package packagea;
public class ClassA{
	
}

[Knute Snortum]

package packageB; says "look in the folder packageB" for the class. import packageA.ClassA; says "you can find ClassA in the folder packageA". So you need to launch the program from a folder that can see both packageA and pacakgeB, or you need to have a classpath entry to each folder.

[Travis Roberts]

Knute Snortum wrote:package packageB; says "look in the folder packageB" for the class. import packageA.ClassA; says "you can find ClassA in the folder packageA". So you need to launch the program from a folder that can see both packageA and pacakgeB, or you need to have a classpath entry to each folder.

Thank you!