What's up with this?

[Steve Cohen]

I realize this may not be the appropriate place for this question but why can't
I do this?

//file a:

import java.awt.*;
public class a {
    void paint (Graphics g) {
        ...
    }

}

//file b:
import java.awt.*;
import a;

public class b {
    public a A;
    ...
    void paint (Graphics g) {
        A.paint(g);
    }
}

The compilation of file b fails with an error message about an unknown method
paint( java.awt.Graphics )

WHY?  This code compiles fine if it is all in one file