Classes and SubClasses

Question

How do you explicitly call a certain constructor in the superclass in the cunstructor of the subclass?
For clarity look at the following example:
This is ClassOne:
import java.io.*;
public class ClassOne {
public ClassOne() {
System.out.println("ClassOne Constructor One");
public ClassOne(String strX) {
System.out.println("ClassOne Constructor Two");
This is ClassTwo
import java.io.*;
public class ClassTwo extends ClassOne {
/** Creates a new instance of ClassTwo */
public ClassTwo() {
System.out.println("ClassTwo First Constructor");
public ClassTwo(String strX) {
System.out.println("ClassTwo Second Constructor");
public static void main(String[] args) {
ClassTwo X = new ClassTwo("X");
So the problem is I want the second constructor of ClassTwo to call the second constructor in ClassOne instead of the first constructor of ClassOne.

Answer 1

Hi billy,
As passgodev suggested you have to insert a super("X") statement in your code.I will explain you why this happens:
public ClassTwo() {
System.out.println("ClassTwo First Constructor");
public ClassTwo(String strX) {
System.out.println("ClassTwo Second Constructor");
}The compiler inserts a no-argument super() call as the first statement in your constructors to call the super class constructors.So,your code changes to:
public ClassTwo() {
super();
System.out.println("ClassTwo First Constructor");
public ClassTwo(String strX) {
super();
System.out.println("ClassTwo Second Constructor");
}So,you just need to pass arguments to the super() method to call the overloaded constructor of ClassOne i.e
public ClassTwo(String strX) {
super(strX);
System.out.println("ClassTwo Second Constructor");
}I hope that helps!!!