Why these varargs methods (which work fine in Java 6) are ambiguous in Java 8

Question

This code compiles and runs in Java 6 (IBM Java 6) but does not compile in Java 8 (IBM Java 8, and Eclipse's built-in compiler) :

public class App {
    public static void main(String[] args) {
        App app = new App();
        app.test(true, new Object());
    }

    void test(boolean b, Object... objects) {
    }

    void test(Object... objects) {
    }
}

The compilation error is:

The method test(boolean, Object[]) is ambiguous for the type App

I found this problem while migrating a real application from Java 6 to Java 8. This code looks ok to me as varargs methods are usualy used as a last resort when Java chooses among overloaded methods.

What is the problem here?

Answer 1

I think this is because of Object type. Compiler thinks that boolean parameter is a subclass of Object (maybe because of autoboxing?), so it treats it as another vararg.