Use of super keyword to call super class constructor in Java

// Program to use super keyword to call Super class constructor to 
// initialize super class instance variables
class Box 
{
private double width;
private double height;
private double depth;
Box(Box ob) 
{ 
 width = ob.width;
 height = ob.height;
 depth = ob.depth;
}
Box(double w, double h, double d) 
{
 width = w;
 height = h;
 depth = d;
}
Box() 
{
 width = 1; 
 height = 1; 
 depth = 1; 
}
Box(double len) 
{
 width = height = depth = len;
}
double volume() 
{
 return width * height * depth;
}
}
class BoxWeight extends Box 
{
double weight;
BoxWeight(BoxWeight ob) 
{ 
 super(ob);
 weight = ob.weight;
}
BoxWeight(double w, double h, double d, double m) 
{
 super(w, h, d); 
 weight = m;
}
BoxWeight() 
{
 super();
 weight = 1;
}
BoxWeight(double len, double m) 
{
 super(len);
 weight = m;
}
}
class  BoxWeightDemo2 
{
public static void main(String args[ ]) 
{
 BoxWeight b1 = new BoxWeight(10, 15, 20, 25.75);
 BoxWeight b2 = new BoxWeight(2, 3, 4, 2.25);
 BoxWeight b3 = new BoxWeight(); 
 BoxWeight b4 = new BoxWeight(5, 6);
 BoxWeight b5 = new BoxWeight(b1);
 double vol;

 vol = b1.volume();
 System.out.println("Volume of b1 is " + vol);
 System.out.println("Weight of b1 is " + b1.weight);
 System.out.println("");
 vol = b2.volume();
 System.out.println("Volume of b2 is " + vol);
 System.out.println("Weight of b2 is " + b2.weight);
 System.out.println("");
 vol = b3.volume();
 System.out.println("Volume of b3 is " + vol);
 System.out.println("Weight of b3 is " + b3.weight);
 System.out.println("");
 vol = b4.volume();
 System.out.println("Volume of b4 is " + vol);
 System.out.println("Weight of b4 is " + b4.weight);
 System.out.println("");
 vol = b5.volume();
 System.out.println("Volume of b5 is " + vol);
 System.out.println("Weight of b5 is " + b5.weight);
}
}
 
Outout:
Volume of b1 is 3000.0
Weight of b1 is 25.75
Volume of b2 is 24.0
Weight of b2 is 2.25
Volume of b3 is 1.0
Weight of b3 is 1.0
Volume of b4 is 125.0
Weight of b4 is 6.0
Volume of b5 is 3000.0
Weight of b5 is 25.75