Class

The introduction to object-oriented concepts in
the lesson titled
Object-oriented Programming Concepts used a bicycle class as an example,
with racing bikes, mountain bikes, and tandem bikes as subclasses.

Here is sample code for a possible implementation of a Bicycle class, to give you an overview of a
class declaration. Subsequent sections of this
lesson

will back up and explain class declarations
step by step. For the moment, don't concern yourself with the details.

public class Bicycle {

	

    // the Bicycle class has three fields

    public int cadence;

    public int gear;

    public int speed;

	

    // the Bicycle class has one constructor

    public Bicycle(int startCadence, int startSpeed, int startGear) {

        gear = startGear;

        cadence = startCadence;

        speed = startSpeed;

    }

	

    // the Bicycle class has four methods

    public void setCadence(int newValue) {

        cadence = newValue;

    }

	

    public void setGear(int newValue) {

        gear = newValue;

    }

	

    public void applyBrake(int decrement) {

        speed -= decrement;

    }

	

    public void speedUp(int increment) {

        speed += increment;

    }

	

}

A class declaration for a MountainBike class that is a subclass of Bicycle might look like this:

public class MountainBike extends Bicycle {

	

    // the MountainBike subclass has one field

    public int seatHeight;



    // the MountainBike subclass has one constructor

    public MountainBike(int startHeight, int startCadence, int startSpeed, int startGear) {

        super(startCadence, startSpeed, startGear);

        seatHeight = startHeight;

    }	

	

    // the MountainBike subclass has one method

    public void setHeight(int newValue) {

        seatHeight = newValue;

    }	



}

MountainBike inherits all the fields and methods of Bicycle and adds the field seatHeight and a method to set it (mountain bikes have seats that can be moved up and down
as the terrain demands).