Remote Control

// the command interface
public interface Command {

    public void execute();

    public void undo();
}

import java.util.Stack;

// invoker
public class DeviceButton {
    Stack<Command> stack = new Stack<Command>();
    public void execute(Command cmd){

        System.out.println("Device button is pressed!");
        stack.add(cmd);
        cmd.execute();
    }

    public void undo(Command cmd) {
        System.out.println("Undoing last command!");
        stack.add(cmd);
        cmd.undo();

    }
}
public interface ElectronicDevice {

    public void on();

    public void off();

    public void volumeUp();

    public void volumeDown();

}
// the client
public class PlayWithRemote{

    public static void main(String[] args){
        DeviceButton button = new DeviceButton();
        //TV commands
        // create command receiver
        ElectronicDevice newTV = RemoteControl.GetTelevision();
        // create a concrete command
        TurnOn onTVCommand = new TurnOn(newTV);
        TurnOff offTVCommand = new TurnOff(newTV);
        VolumeUp tvVolumeUp = new VolumeUp(newTV);
        VolumeDown tvVolumeDown = new VolumeDown(newTV);
        // create invoker


        // invoke command


        // create another concrete command


        // invoke another concrete command
        button.execute(onTVCommand);
        button.undo(onTVCommand);
        button.execute(offTVCommand);
        button.undo(offTVCommand);

        //Stereo Commands
        ElectronicDevice newStereo = RemoteControl.GetStereo();
        //concrete commands for stereo
        TurnOn onStereoCommand = new TurnOn(newStereo);
        TurnOff offStereoCommand = new TurnOff(newStereo);
        VolumeUp stereoVolumeUp = new VolumeUp(newStereo);
        VolumeDown stereoVolumeDown = new VolumeDown(newStereo);
        // create invoker
        // invoke commands
        button.execute(onStereoCommand);
        button.undo(onStereoCommand);
        button.execute(stereoVolumeUp);
        button.undo(stereoVolumeUp);
        button.execute(stereoVolumeDown);
        button.undo(stereoVolumeDown);
        button.execute(offStereoCommand);
        button.undo(offStereoCommand);
    }
}

public class RemoteControl {

    // return a command receiver
    public static ElectronicDevice GetTelevision(){

        return new Television();
    }

    public static ElectronicDevice GetStereo() {

        return new Stereo();
    }
}
// a comand receiver
public class Stereo implements ElectronicDevice {

    private int volume = 0;

    public void on() {

        System.out.println("Stereo is on");

    }

    public void off() {

        System.out.println("Stereo is off");

    }

    public void volumeUp() {

        volume++;

        System.out.println("Stereo Volume is at: " + volume);

    }

    public void volumeDown() {

        volume--;

        System.out.println("Stereo is at: " + volume);

    }

}
// a comand receiver
public class Television implements ElectronicDevice {

    private int volume = 0;

    public void on() {

        System.out.println("TV is on");

    }

    public void off() {

        System.out.println("TV is off");

    }

    public void volumeUp() {

        volume++;

        System.out.println("TV Volume is at: " + volume);

    }

    public void volumeDown() {

        volume--;

        System.out.println("TV Volume is at: " + volume);

    }

}
// a concrete command
public class TurnOff implements Command {

    ElectronicDevice myDevice;

    public TurnOff(ElectronicDevice device){

        myDevice = device;
    }

    public void execute() {

        myDevice.off();
    }

    @Override
    public void undo() {
       myDevice.on();
    }
}
// a concrete command
public class TurnOn implements Command {

    ElectronicDevice myDevice;

    public TurnOn(ElectronicDevice device){
        // register receiver
        myDevice = device;
    }

    public void execute() {

        myDevice.on();
    }
    @Override
    public void undo() {
        myDevice.off();
    }
}

public class VolumeDown implements Command {

    ElectronicDevice myDevice;

    public VolumeDown(ElectronicDevice device){

        myDevice = device;
    }

    public void execute() {

        myDevice.volumeDown();
    } @Override
    public void undo() {
        myDevice.volumeUp();
    }


}

public class VolumeUp implements Command {

    ElectronicDevice myDevice;

    public VolumeUp(ElectronicDevice device){

        myDevice = device;
    }

    public void execute() {

        myDevice.volumeUp();
    }
    @Override
    public void undo() {
        myDevice.volumeDown();
    }

}