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Java Tutorial : Inheritance Has A Relationship (Car)

Java Tutorial : Inheritance Has A Relationship (Car)

Car.java

public class Car
{

    private String color;
    private int maxSpeed;

    public Car(String color, int maxSpeed)
    {
        super();
        this.color = color;
        this.maxSpeed = maxSpeed;
    }

    public String getColor()
    {
        return color;
    }

    public void setColor(String color)
    {
        this.color = color;
    }

    public int getMaxSpeed()
    {
        return maxSpeed;
    }

    public void setMaxSpeed(int maxSpeed)
    {
        this.maxSpeed = maxSpeed;
    }

    public void carInfo()
    {

        System.out.println("Car Color= " + color + ", Max Speed= " + maxSpeed);

    }
}

Engine.java

public class Engine
{
    public void start()
    {

        System.out.println("Engine Started:");

    }

    public void stop()
    {

        System.out.println("Engine Stopped:");

    }
}

/**
 * 
 * MarutiSwift is specific type of Car which extends Car class means MarutiSwift
 * IS-A Car.
 * 
 * MarutiSwift extends Car and thus inherits all properties and methods from Car
 * (except final and static).
 * 
 * MarutiSwift can also define all its specific functionality.
 */
public class MarutiSwift extends Car
{
    /*
     * MarutiSwift HAS-A Engine
     */
    private Engine engine;

    public MarutiSwift(String color, int maxSpeed, Engine engine)
    {
        super(color, maxSpeed);
        this.engine = engine;
    }

    public void startMarutiSwift()
    {
        engine.start();
    }

}

/**
 * RelationsDemo class is making object of MarutiSwift class and initialized it.
 * Though MarutiSwift class does not have setColor(), setMaxSpeed() and carInfo()
 * methods still we can use it due to IS-A relationship of MarutiSwift class with Car
 * class.
 */

public class RelationshipDemo
{

    public static void main(String[] args)
    {

        Engine engine = new Engine();
        MarutiSwift marutiSwift = new MarutiSwift("Red", 200, engine);
        marutiSwift.carInfo();
        marutiSwift.startMarutiSwift();
    }
}