Description David Stubbs 2005-06-29 14:00:39 EDT

The basic problem is that when building the varargs for A... args where A has
been specified as String, the compiler is ignoring the specified type and
building an array of Objects instead.

Note that this behaviour has been introduced since at least Eclipse 3.1rc1.

This causes a ClassCastException in the following code:
public class MyTest {

    public static void main(String[] args) {
        Test<String> t = new Tester();
        t.method("1st string");
    }
    
    static abstract class Test<A> {
        abstract void method(A... args);
    }
    
    static class Tester extends Test<String> {

        void method(String... args) {
            System.out.println(args);
            call(args);
        }
        
        void call(String[] args) {
            for ( String str : args )
                System.out.println("String: "+str);
        }
    }
    
}

the exact output when compiled with Eclipse 3.1 is:
Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object;
	at MyTest$Tester.method(MyTest.java:1)
	at MyTest.main(MyTest.java:10)

when compiled using Eclipse 3.1rc1, or javac from Sun's JDK1.5.0_01 the output
is as I would expect:
[Ljava.lang.String;@360be0
String: 1st string

I don't know which is the "correct" result, but if the latest Eclipse is then I
would expect a compiler warning or error, rather than a run-time ClassCastException.