Parameterized constructors

class Box
    {    double width;
          double height;
          double depth;

          Box( double w, double h, double d)
          {    System.out.println("constructing box");
                width=w;
                height=h;
                depth=d;
         }

         double volume( )
         {       
                   return width*height*depth;
         }
     }
class BoxDemo
     {
               public static void main( String args[])
               {    Box mybox1=new Box(10,20,15);
                     Box mybox2=new Box(3,6,9);
                     double vol;
                     vol=mybox1.volume( );
                     System.out.println("Volume of first box is"+vol);
                     vol=mybox2.volume( );
                     System.out.println("Volume of second box is"+vol);
                 }
      }


In a parameterised constructor the parameters are passed while creating a object as done here:
Box mybox1=new Box(10,20,15);
The values 10,20 and 15 are passed to the constructor of class box and width, height and depth of box 1 will be initialized to these values.
Similarly we are passing values 3,6 and 9 for box 2, hence its width,height and depth are initialized to 3, 6 and 9.

hence the output of above program will be:

Volume of first box is3000
Volume of second box is162            




To know about unparameterized constructors click here