Explain Parameterized Constructor In Java With Program And Examples, Program For Parametrized Constructor
In This Topic & Blog Having Any Query Then Post your Comment and Suggestion Below
Parameterized Constructors
While the
Box( )
constructor in the preceding example does initialize a
Box
object, it is not
very useful—all boxes have the same dimensions. What is needed is a way to construct
Box
objects of various dimensions. The easy solution is to add parameters to the constructor. As
you can probably guess, this makes them much more useful. For example, the following version
of
Box
defines a parameterized constructor that sets the dimensions of a box as specified by
those parameters. Pay special attention to how
Box
objects are created.
/* Here, Box uses a parameterized constructor to
initialize the dimensions of a box.
*/
class Box {
double width;
double height;
double depth;
// This is the constructor for Box.
Box(double w, double h, double d) {
width = w;
height = h;
depth = d;
}
// compute and return volume
double volume() {
return width * height * depth;
}
}
class BoxDemo7 {
public static void main(String args[]) {
// declare, allocate, and initialize Box objects
Box mybox1 = new Box(10, 20, 15);
Box mybox2 = new Box(3, 6, 9);
double vol;
// get volume of first box
vol = mybox1.volume();
System.out.println("Volume is " + vol);
// get volume of second box
vol = mybox2.volume();
System.out.println("Volume is " + vol);
}
}
The output from this program is shown here:
Volume is 3000.0
Volume is 162.0
As you can see, each object is initialized as specified in the parameters to its constructor.
For example, in the following line,
Box mybox1 = new Box(10, 20, 15);
the values 10, 20, and 15 are passed to the
Box( )
constructor when
new
creates the object.
Thus,
mybox1
’s copy of
width height
,
, and
depth
will contain the values 10, 20, and 15,
respectively.