Getting error for generic interface: The interface Observer cannot be implemented more than once with different arguments:

Question

I am getting this error in Eclipse while writing a GWT app

The interface Observer cannot be implemented more than once with different arguments:

Answer 1

Not sure this can help, but I came across the same Java compile error today.

I partially solved my case by extracting all the shared implementation I could get to a parametrized abstract class:

public enum Example {
    ;
    static interface Observer { public void update (T o); }
    static abstract AbstractObserver implements Observer {
        public void update (T o) { /* shared stuff I can put here */ }
    }
    static Composite extends AbstractObserver {
        public void update (T o) {
            super(o);
            /* type-specific code here */
        }
    }
    static CompositeWordLists extends AbstractObserver {
        public void update (T o) {
            super(o);
            /* type-specific code here */
        }
    }
}