Method call

[gaurav gupta sitm]

 class MainClass { 
  void test(Object s)    { System.out.println ("Object version");    } 
  void test(MainClass s)    { System.out.println ("MainClass version");    } 
  void test(SubMainClass s) { System.out.println ("SubMainClass version"); } 
//void test(String s) { System.out.println ("String version"); } 

  public static void main (String args[]) { 
    MainClass c = new MainClass (); 
    c.test (null);        
   
  } 
} 

class SubMainClass extends MainClass{ 
} 

Output : SubMainClass version

in this program , how compiler perform selection of method call ???

Thanks ,

[David Byron]

Just as Object is the parent of all objects, null is the child of all objects. It's the ultimate child. So when the argument used to resolve a call to an overloaded method happens to be null, the compiler looks for the most specific type.

[Stephan van Hulst]

The compiler always chooses the most specific overloading that is applicable. SubMainClass is more specific than MainClass or Object, and it is applicable to null, so that's what it chooses.