Why is a superclass constructer called automatically?

Question

I have two simple classes as shown:
public class Class1 {
public Class1() {
System.out.println("Hello World");
public class Class2 extends Class1 {
public Class2() {
static public void main(String[] args) {
Class2 c2 = new Class2();
When I run Class2 (i.e. java Class2) it prints out "Hello World". It looks as though the constructor for class 2 is automatically calling the constructor from its superclass (class 1). I thought that you had to specify this with super(). Any Advice?

Answer 1

this should be in new to java programming.
anyway, the constructor of the super class need to be call automatically so that the object is in the proper state. suppose you extends from JFrame with class call MyJFrame. when you create your MyJFrame the code that construct the JFrame must be automatically called so that it works fine, after the constructor of the super class get called to initialize it's data then your subclass can initialize its own data. the constructor that is called automatically is the no-argument constructor. so if your super class does not have no-argument constructor you must explicitly call the appropiate super constructor in your subclass. also you cannot create instance of subclass that extends from the super class that has only private no-argument constructor.