class Test
{  
    int  value1;  
    int  value2;  
    Test()  
    {  
        value1 = 10;  
        value2 = 20;  
        System.out.println("Inside Constructor");  
    }  
    public void display()  
    {  
        System.out.println("Value1 === "+value1);  
        System.out.println("Value2 === "+value2);  
    }  
    public static void main(String args[])  
    {  
        Test d1 = new Test();  
        d1.display();  
    }  
}

Inside Constructor
Value1 === 10
Value2 === 20

class Test
{  
      int  value1;  
      int  value2;  
      Test()  
      {  
        value1 = 10;  
        value2 = 20;  
        System.out.println("First Constructor");  
      }  
      Test(int a)  
      {  
        value1 = a;  
        System.out.println("Second Constructor");  
      }  
      Test(int a,int b)  
      {  
        value1 = a;  
        value2 = b;  
        System.out.println("Third Constructor");  
      }  
      public void display()  
      {  
        System.out.println("Value1 "+value1);  
        System.out.println("Value2 "+value2);  
      }  
      public static void main(String args[])  
      {  
        Test d1 = new Test();  
        Test d2 = new Test(30);  
        Test d3 = new Test(30,40);  
        d1.display();  
        d2.display();  
        d3.display();  
      }  
} 

First Constructor
Second Constructor
Third Constructor
Value1 10
Value2 20
Value1 30
Value2 0
Value1 30
Value2 40

class Test  
{  
   int  value1;  
   int  value2;  
    Test()  
    {  
      value1 = 1;  
      value2 = 2;  
      System.out.println("First Parent Constructor");  
    }  
    Test(int a)  
    {  
      value1 = a;  
      System.out.println("Second Parent Constructor");  
    }  
    public void display()  
    {  
        System.out.println("Value1 "+value1);  
        System.out.println("Value2 "+value2);  
    }  
    public static void main(String args[])  
    {  
        TestChild d1 = new TestChild();  
        d1.display();  
    }  
}  
class TestChild extends Test{  
    int value3;  
    int value4;  
    TestChild()  
    {  
        //super(1);  
        value3 = 3;  
        value4 = 4;  
        System.out.println("Child Constructor");  
    }  
    public void display()  
    {  
        System.out.println("Value1  "+value1);  
        System.out.println("Value2  "+value2);  
        System.out.println("Value1  "+value3);  
        System.out.println("Value2  "+value4);  
   }  
}  

First Parent Constructor
Child Constructor
Value1  1
Value2  2
Value1  3
Value2  4

class Rectangle {  
    private int x, y;  
    private int width, height;  
          
    public Rectangle() {  
        this(0, 0, 0, 0);  
    }  
    public Rectangle(int width, int height) {  
        this(0, 0, width, height);  
    }  
    public Rectangle(int x, int y, int width, int height) {  
        this.x = x;  
        this.y = y;  
        this.width = width;  
        this.height = height;  
    }  
	public void show(){
		System.out.println("X="+this.x);
		System.out.println("Y="+this.y);
		System.out.println("width="+this.width);
		System.out.println("height="+this.height);
	}
 }
public class Test{
	public static void main(String args[]){
		Rectangle obj=new Rectangle();
		Rectangle obj1=new Rectangle(1,2);
		Rectangle obj2=new Rectangle(1,2,3,4);
		obj.show();
		obj1.show();
		obj2.show();
	}
}

X=0
Y=0
width=0
height=0
X=0
Y=0
width=1
height=2
X=1
Y=2
width=3
height=4