Java – how does null work in this code?

See English answers > method overloading and choosing the most specific type 9

class Test1{
    public void doStuff(Object o){
    System.out.println("In Object");
}

    public void doStuff(String o){
        System.out.println("In String");
    }
}

public class TTest {
    public static void  main(String args[]){    
        Test1 t = new Test1();
        t.doStuff(null);
    }
}

Output:

Solution

Java always tries to use the most specific method version

Self summoning

t.doStuff(null);

Applicable to both methods

t.doStuff(Object o)
t.doStuff(String o)

Java will choose the most specific method description, namely

t.doStuff(String o)