Tutorial 37 Abstract Classes

//Tutorial 37 (Abstract Classes)
//Abstract classes are something you can use when you want to start creating a class hierarchy.
//But the base class is not going to be doing anything in itself, its only gonna act as base for other classes.
//Machine is a base class

//App.java
public class App {

    public static void main(String[] args) {
        Camera cam1 = new Camera();
            cam1.setId(5);

        Car car1 = new Car();
            car1.setId(4);
            car1.run();

    //Machine machine1 = new Machine(); //Error: "cannot instantiate type Machine" see Machine.java comment

    }

}

//---------------------------------------------------------------------------------------------------------------------------------------
//Machine.java

public abstract class Machine { //adding "abstract" to "public class Machine {" prevents the user of this heirarchy from creating the base parent class, in this case: Machine
    //abstract classes can have abstract methods



    private int id;
        //then right click>generate getters and setters>check mark id> boom:
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;

    }

    public abstract void start(); //make methods abstract and with "@Override" to make child classes implement them
    public abstract void doStuff();
    public abstract void shutUp();


    public void run(){
        start();
        doStuff();
        shutUp();
    }
}
//---------------------------------------------------------------------------------------------------------------------------------------

public class Camera extends Machine {

    @Override
    public void start() {
        System.out.println("Starting camera.");
    }

    @Override
    public void doStuff() {
        System.out.println("Taking a photo");

    }

    @Override
    public void shutUp() {
        System.out.println("Shutting down the camera.");

    }

}

//---------------------------------------------------------------------------------------------------------------------------------------

public class Car extends Machine { //when you say "Car extends Machine", you are making a very strong statement that "Car is a machine.

    @Override
    public void start() {
        System.out.println("Starting camera.");
    }

    @Override
    public void doStuff() {
        System.out.println("Do stuff in car.");

    }

    @Override
    public void shutUp() {
        System.out.println("Shut up Optimus Prime.");

    }

}




//---------------------------------------------------------------------------------------------------------------------------------------
/*Run Results:
Starting camera.
Do stuff in car.
Shut up Optimus Prime.
*/