Consider the following example:

public class Sandbox {
    public interface Listener<T extends JComponent> {
        public void onEvent(T event);
    }

    public interface AnotherInterface extends Listener<JPanel>, Listener<JLabel> {
    }
}

This fails with the following error

/media/PQ-WDFILES/programming/Sandbox/src/Sandbox.java:20: Sandbox.Listener cannot be inherited with different arguments: <javax.swing.JPanel> and <javax.swing.JLabel>
        public interface AnotherInterface extends Listener<JPanel>, Listener<JLabel> {
               ^
1 error

Why though? There is no overlap in the generated methods. As a matter of fact, that essentially means

public interface AnotherInterface {
    public void onEvent(JPanel event);
    public void onEvent(JLabel event);
}

No overlap there. So why is it failing?

In case your wondering what I'm doing and have a better solution: I have a bunch of Events and a Listener interface that's almost exactly like the Listener class above. I'm wanting to create an adapter and an adapter interface, and for that I need to extend all the Listener interfaces with a specific event. Is this possible? Is there a better way to do this?

java generics
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