Constructors in Java.

CODE :

package com.ack.learning;

public class Constructors {
private static final String DEFAULT_MSG = "hey";
private static final int DEFAULT_AMOUNT = 25;

private String msg;
private int amount;

public Constructors( String msg, int amount ) {
// use the 'this' keyword to reference to this object instance
// variables, with out, msg and amount refer to the formal parameters
this.msg = msg;
this.amount = amount;
}

public Constructors( String msg ) {
// must be first line in a constructor and calls the constructor
// within this class with those formal parameters
this( msg, DEFAULT_AMOUNT );
}

public Constructors() {
// must be first line in a constructor and calls the constructor
// within this class with those formal parameters
this( DEFAULT_MSG );
}

public static void main( String[] args ) {
// here, we demonstrate how all three constructors
// can be called to construct an object
new Constructors();
}
}