javac treats Object as a direct supertype of all interfaces

Name: mc57594 Date: 05/21/97


Object is not a direct supertype of an interface. In other
words, if an interface type is searched for a declaration during lookup,
lookup does not proceed thence into Object; similarly, an interface that
happens to declare an abstract method with the same signature as a
method in Object is NOT overriding the method in Object!

However javac treats all interfaces as though they were implicitly
directly extending/implementing Object:

interface J {
    void notify (); // error - overrides final method
    void finalize () throws J; // error - wider 'throws' list
    J clone (); // error - different return type
}

This interface is well-formed, but javac rejects it.

Similarly, the following code is illegal; however javac accepts it:

interface J {
}

class Test {
    void f (J j) {
        j.toString(); // OK - toString is a member of J
    }
}
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