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javastringobjectoop

Checking With String and Object

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 ?

Solution

  • 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.