10. Polymorphism Example

Practical use of polymorphism - array of shape-derived objects, Circles, Rectangles, and Triangles:

public abstract class Shape {
    public abstract void draw();
}
public class Circle extends Shape {
    public void draw() {
        System.out.println("I am drawing a Circle");
    }
}
public class Rectangle extends Shape {
    public void draw() {
        System.out.println("I am drawing a Rectangle");
    }
}
public class Triangle extends Shape {
    public void draw() {
        System.out.println("I am drawing a Triangle");
    }
}

public class TestShapeArray {
    public static void main( String args [] ) {
        Shape [] myshapes = new Shape [4];
        myshapes [0] = new Circle();
        myshapes [1] = new Rectangle();
        myshapes [2] = new Circle();
        myshapes [3] = new Triangle();
        System.out.println(myshapes[0].draw());
        System.out.println(myshapes[1].draw());
        System.out.println(myshapes[2].draw());
        System.out.println(myshapes[3].draw());	
    } // end of main
} // end of TestShapeArray 

Test Results:

    I am drawing a Circle
    I am drawing a Rectangle
    I am drawing a Circle
    I am drawing a Triangle