Page 178 - CTS - CSA TP - Volume 2

COMPUTER SOFTWARE APPLICATION - CITS

EXERCISE 110 : Create abstract classes and methods

Objectives

At the end of this exercise you shall be able to
• develop Java programs to Create abstract classes and methods.

Requirements

Tools/Materials
• PC / laptop with windows OS
• SDK software
• Test editor (Visual studio/ subline/ notepad)

Procedure

TASK 1: Create abstract classes and methods example

// Abstract class
abstract class Shape {
// Abstract method
public abstract double calculateArea();

// Concrete method
public void displayArea() {
System.out.println(“Area: “ + calculateArea());
}
}

// Concrete class 1
class Circle extends Shape {
private double radius;
// Constructor
public Circle(double radius) {

this.radius = radius;
}
// Implementation of abstract method
@Override
public double calculateArea() {

return Math.PI * radius * radius;
}
}
// Concrete class 2

163