Inheritance in Java

Inheritance allows you to derive a class from another class for a hierarchy of classes that share a set of attributes and methods.

Source Code

class Bicycle {
    // Bicycle class has two fields
    public int gear;
    public int speed;
    // Bicycle class has one constructor
    public Bicycle(int gear, int speed) {
        this.gear = gear;
        this.speed = speed;
    }
    // Bicycle class has three methods
    public void applyBrake(int decrement) {
        speed -= decrement;
    }
    public void speedUp(int increment) {
        speed += increment;
    }
    // toString() method to print info of Bicycle
    public String toString() {
        return("No of gears are " + gear + "n" + "speed of bicycle is " + speed);
    }  
}
// derived class
class MountainBike extends Bicycle {
    // the MountainBike subclass adds one more field
    public int seatHeight;
    // the MountainBike subclass has one constructor
    public MountainBike(int gear,int speed, int startHeight) {
        // invoking base-class(Bicycle) constructor
        super(gear, speed);
        seatHeight = startHeight;
    }          
    // the MountainBike subclass adds one more method
    public void setHeight(int newValue) {
        seatHeight = newValue;
    }   
    // overriding toString() method of Bicycle to print more info
    @Override public String toString() {
        return (super.toString() + "nseat height is " + seatHeight);
    }   
}
// driver class
public class Test {
    public static void main(String args[]) {
        MountainBike mb = new MountainBike(3, 100, 25);
        System.out.println(mb.toString());
    }
}