Java – how do overloaded methods work?

public class Test1  {

public class Test1  {

    public static void main(String[] args)   {
        Test1 test1 = new Test1();
        test1.testMethod(null);
    }

    public void testMethod(String s){
        System.out.println("Inside String Method");     
    }

    public void testMethod(Object o){
        System.out.println("Inside Object Method"); 
    }
}

When I try to run the given code, I get the following output:

Anyone can explain why a method using a string type parameter is called?

Solution

The most important method is to select the most specific method parameters

In this case, string is a subclass of object Therefore, string becomes more specific than object Therefore, the inside string method is printed

Directly from jls-15.12 two point five

As BMT and lastfreenickname correctly prompt, (object) null will cause overloaded methods using the object type method to be called