class file relationships for Java

A Java source file Javac out multiple class files! What's going on?

1. When you define several classes in a file, this can happen, such as
public class A {}
Class B {}
Class C {}
So each class will be a. class file

2. This happens when you define an internal class, such as
public class A {
Class B {
}
}
This will produce two class files, one a.class, one a$b.class

3. This occurs when an anonymous class is used, such as
public class A {
void xxx () {
Button.addactionlisener (new ActionListener () {...});
}
}
This will also produce multiple classes, a a.class, a a$1.class
}

class file relationships for Java