Question

In the code below, the output is : S1S2. Why do we get the that result?

 public class S1 {
     public static void main(String[] args) {
         new S2();
     }
     S1(){
         System.out.print("S1");
     }
 }
 class S2 extends S1{
     S2(){
         System.out.print("S2");
     }
 }

Answer 1

Since S2 extends S1, it’s equivalent to calling all the constructors in a top-level down order.

Java will first create the parent object, S1 and call it’s constructor. Then move down to the next object, S2 with it’s constructor.