Checking With String and Object [duplicate]

Question

Here is the code:

public class OverloadingByObject {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Object object = null;
        new OverloadingByObject().SayHi(null);
        new OverloadingByObject().SayHi(object);
    }

    public void SayHi(String str) {

        System.out.println("String called");
    }

    public void SayHi(Object obj) {

        System.out.println("Object called");
    }
}

When I am passing null it should call the method of Object. What is the reason it is calling method of String ?

Eran · Accepted Answer · 2015-05-22 13:33:57Z

7

null can be assigned to any reference type. When deciding which overloaded version of a method will be called, the method with the most specific arguments is chosen. String is more specific than Object (since String is a sub-class of Object). Therefore SayHi(String str) is called for a null argument.

answered May 22, 2015 at 13:33

Eran

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7 Comments

Kishan Bheemajiyani Over a year ago

So u are sure that it will prefer first Sub-class metod.

Eran Over a year ago

@Krishna It will prefer the method with the most specific argument types. However, if you add another method, such as SayHi(Integer i), calling SayHi(null) won't pass compilation, since neither Integer nor String is more specific than the other.

user987339 Over a year ago

Running this example I am getting "Object called" twice.

Eran Over a year ago

@user987339 strange, I'm getting String called Object called, which is the expected behavior.

user987339 Over a year ago

can you paste it on ideone?

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