Dynamic Method Dispatch Example in Java

This article demonstrates a Dynamic Method Dispatch Example in Java.

Problem Statement

Write a program in java to Create a class Figure and its 2 subclasses Rectangle and Triangle and calculate its area using dynamic method dispatch.

Solution

class Figure {
    double calculateArea() {
        return 0.0;
    }
}

class Rectangle extends Figure {
    double length;
    double width;

    Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }

    @Override
    double calculateArea() {
        return length * width;
    }
}

class Triangle extends Figure {
    double base;
    double height;

    Triangle(double base, double height) {
        this.base = base;
        this.height = height;
    }

    @Override
    double calculateArea() {
        return 0.5 * base * height;
    }
}

public class Main {
    public static void main(String[] args) {
        Figure[] figures = new Figure[3];
        figures[0] = new Rectangle(5.0, 4.0);
        figures[1] = new Triangle(6.0, 8.0);
        figures[2] = new Rectangle(3.0, 7.0);

        for (Figure figure : figures) {
            System.out.println("Area: " + figure.calculateArea());
        }
    }
}

In this program:

We have a base class Figure with a method calculateArea() that returns 0.0 by default.
Two subclasses, Rectangle and Triangle, inherit from Figure and override the calculateArea() method to calculate the area specific to each figure.
In the main method, we create an array of Figure objects, which can hold objects of both the base class and its subclasses.
We create instances of Rectangle and Triangle and store them in the figures array.
Finally, we use a for loop to iterate through the figures array and call the calculateArea() method for each figure. Dynamic method dispatch ensures that the correct calculateArea() method (either from Rectangle or Triangle) is called based on the actual object type.

Problem Statement

Solution

Further Reading