Question

I was developing the below class..

public class Test1 
{
    public void method(Object o)
    {
        System.out.println("Object Verion");
    }   
    public void method(String s)
    {
        System.out.println("String Version");
    }



    public static void main(String args[])
    {
        Test1 question = new Test1();
        //question.method(question);

        question.method(null);
    }

}

Now upon executing it invokes string version as output So please advise here string is treated as null and what should we pass to invoke the object version.Thanks in advance

Answer 1

All other things being equal, the most-specific method will be called. From the JLS:

15.12.2.5. Choosing the Most Specific Method

If more than one member method is both accessible and applicable to a
method invocation, it is necessary to choose one to provide the
descriptor for the run-time method dispatch. The Java programming
language uses the rule that the most specific method is chosen.

The informal intuition is that one method is more specific than
another if any invocation handled by the first method could be passed
on to the other one without a compile-time type error.

question.method(null) could mean either the String or Object overload, but since String is more specific (narrower) than Object, the String overload is the method that is called.