Name: krT82822 Date: 10/07/99


//Begin A1.java
/*
 Why is in class A1 the invocation x.m(x) ambiguous and the two other
 invocations not? According to the JLS (15.11.2.2) all invocations are
 ambiguous. In all three cases both methods I/m(J) and J/m(I) are
 applicable.
 */

interface I {
    void m(J x);
}

interface J extends I {
    void m(I x);
}

abstract class A1 implements J {
    void test(J x) {
        this.m(x); // invokevirtual m(J).
        ((A1) x).m(x); // invokevirtual m(J).
        x.m(x); // Reference to m is ambiguous.
    }
}
//End A1.java

//Begin A2.java
/*
 If we use abstract classes instead of interfaces, then all three
 invocations are ambiguous. Why are abstract classes treated
 differently?
 */

abstract class I {
    abstract void m(J x);
}

abstract class J extends I {
    abstract void m(I x);
}

abstract class A2 extends J {
    void test(J x) {
        this.m(x); // Reference to m is ambiguous.
        ((A2) x).m(x); // Reference to m is ambiguous.
        x.m(x); // Reference to m is ambiguous.
    }
}
//End A2.java

--------------

10/7/99 eval1127@eng -- may be related to 4133897
(Review ID: 93681)
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