Command Pattern Implementation

patterns/command/AlexaDevice.java

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+package patterns.command;
+
+import patterns.command.commands.Command;
+import patterns.command.commands.NoOpCommand;
+
+public class AlexaDevice {
+    Command[] onCommands;
+    Command[] offCommands;
+    int slots = 3;
+
+    public AlexaDevice() {
+        onCommands = new Command[slots];
+        offCommands = new Command[slots];
+
+        for (int i = 0; i < slots; i++) {
+            onCommands[i] = new NoOpCommand();
+            offCommands[i] = new NoOpCommand();
+        }
+    }
+
+    public void setCommand(int slot, Command onCommand, Command offCommand) {
+        //slot between 0..2, neither commands can be nll
+        if (onCommand == null || offCommand == null) {
+            throw new IllegalArgumentException("Commands cannot be null!");
+        } else {
+            onCommands[slot] = onCommand;
+            offCommands[slot] = offCommand;
+        }
+    }
+
+    public void activateSlot(int slot) {
+        onCommands[slot].execute();
+    }
+
+    public void deactivateSlot(int slot) {
+        offCommands[slot].execute();
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("\n-------- Alexa Device Controller --------\n");
+        for (int i = 0; i < slots; i++) {
+            sb.append("Slot #" + i + " - " + onCommands[i].getClass().getSimpleName() + "(" + onCommands.getClass().getSimpleName() + ")" +
+                    " - " + offCommands[i].getClass().getSimpleName() + "(" + offCommands.getClass().getSimpleName() + ")" +
+                    "\n");
+        }
+        return sb.toString();
+    }
+}

patterns/command/Main.java

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+package patterns.command;
+
+import patterns.command.commands.EverythingOffCommand;
+import patterns.command.commands.EverythingOnCommand;
+import patterns.command.commands.KitchenLightsOffCommand;
+import patterns.command.commands.KitchenLightsOnCommand;
+import patterns.command.hardware.KitchenLights;
+import patterns.command.hardware.Music;
+
+public class Main {
+
+    public static void main(String[] args) {
+        //Example 1 - Empty slots
+        AlexaDevice alexa = new AlexaDevice();
+        System.out.println(alexa);
+
+//      ---------------------------------------------------------------
+
+        //Example 2 - Kitchen Lights on
+//        AlexaDevice alexa = new AlexaDevice();
+//
+//        //Create an instance
+//        KitchenLights kitchenLights = new KitchenLights();
+//
+//        //Set the slots with new commands
+//        alexa.setCommand(
+//                0,
+//                new KitchenLightsOnCommand(kitchenLights),
+//                new KitchenLightsOffCommand(kitchenLights)
+//        );
+//
+//        System.out.println(alexa);
+//
+//        alexa.activateSlot(0);
+//        alexa.deactivateSlot(0);
+
+//      ---------------------------------------------------------------
+
+        //Example 3 - Everything on!
+//        AlexaDevice alexa = new AlexaDevice();
+//
+//        //Create an instance
+//        KitchenLights kitchenLights = new KitchenLights();
+//        Music music = new Music();
+//
+//        //Set the slots with new commands
+//        alexa.setCommand(
+//                1,
+//                new EverythingOnCommand(music, kitchenLights),
+//                new EverythingOffCommand(music, kitchenLights)
+//        );
+//
+//        System.out.println(alexa);
+//
+//        alexa.activateSlot(1);
+//        alexa.deactivateSlot(1);
+
+    }
+}

patterns/command/commands/Command.java

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+package patterns.command.commands;
+
+public interface Command {
+    public void execute();
+}

patterns/command/commands/EverythingOffCommand.java

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+package patterns.command.commands;
+
+import patterns.command.hardware.KitchenLights;
+import patterns.command.hardware.Music;
+
+public class EverythingOffCommand implements Command {
+    Music music;
+    KitchenLights kitchenLights;
+
+    public EverythingOffCommand(Music music, KitchenLights kitchenLights) {
+        this.music = music;
+        this.kitchenLights = kitchenLights;
+    }
+
+    @Override
+    public void execute() {
+        System.out.println("--- PARTY TIME OVER! ---");
+        kitchenLights.off();
+        music.off();
+        music.setVolume(0);
+        music.setStation(0);
+    }
+
+}

patterns/command/commands/EverythingOnCommand.java

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+package patterns.command.commands;
+
+import patterns.command.hardware.KitchenLights;
+import patterns.command.hardware.Music;
+
+public class EverythingOnCommand implements Command {
+    Music music;
+    KitchenLights kitchenLights;
+
+    public EverythingOnCommand(Music music, KitchenLights kitchenLights) {
+        this.music = music;
+        this.kitchenLights = kitchenLights;
+    }
+
+    @Override
+    public void execute() {
+        System.out.println("--- ITS PARTY TIME! ---");
+        kitchenLights.on();
+        music.on();
+        music.setVolume(10);
+        music.setStation(102.1F);
+    }
+
+}

patterns/command/commands/KitchenLightsOffCommand.java

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+package patterns.command.commands;
+
+import patterns.command.hardware.KitchenLights;
+
+public class KitchenLightsOffCommand implements Command {
+    KitchenLights kitchenLights;
+
+    public KitchenLightsOffCommand(KitchenLights kitchenLights) {
+        this.kitchenLights= kitchenLights;
+    }
+
+    @Override
+    public void execute() {
+        kitchenLights.off();
+    }
+
+}

patterns/command/commands/KitchenLightsOnCommand.java

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+package patterns.command.commands;
+
+import patterns.command.hardware.KitchenLights;
+
+public class KitchenLightsOnCommand implements Command {
+    KitchenLights kitchenLights;
+
+    public KitchenLightsOnCommand(KitchenLights kitchenLights) {
+        this.kitchenLights= kitchenLights;
+    }
+
+    @Override
+    public void execute() {
+        kitchenLights.on();
+    }
+
+}

patterns/command/commands/MusicOffCommand.java

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+package patterns.command.commands;
+
+import patterns.command.hardware.Music;
+
+public class MusicOffCommand implements Command {
+    Music music;
+
+    public MusicOffCommand(Music music) {
+        this.music = music;
+    }
+
+    @Override
+    public void execute() {
+        music.setVolume(0);
+        music.setStation(0);
+        music.off();
+    }
+
+}

patterns/command/commands/MusicOnCommand.java

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+package patterns.command.commands;
+
+import patterns.command.hardware.Music;
+
+public class MusicOnCommand implements Command {
+    Music music;
+
+    public MusicOnCommand(Music music) {
+        this.music = music;
+    }
+
+    @Override
+    public void execute() {
+        music.on();
+        music.setVolume(5);
+        music.setStation(99.9F);
+    }
+
+}

patterns/command/commands/NoOpCommand.java

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+package patterns.command.commands;
+
+public class NoOpCommand implements Command {
+    public void execute() {
+
+    };
+}

patterns/command/hardware/KitchenLights.java

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+package patterns.command.hardware;
+
+public class KitchenLights {
+
+    public void on() {
+        System.out.println("Turning on Kitchen Lights");
+        //activate hardware...
+    }
+
+    public void off() {
+        System.out.println("Turning off Kitchen Lights");
+        //deactivate hardware
+    }
+}

patterns/command/hardware/Music.java

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+package patterns.command.hardware;
+
+public class Music {
+    private int volume;
+    private float station;
+
+    public int getVolume() {
+        return volume;
+    }
+
+    public void setVolume(int volume) {
+        System.out.println("Setting volume to: " + volume);
+        this.volume = volume;
+    }
+
+    public float getStation() {
+        return station;
+    }
+
+    public void setStation(float station) {
+        System.out.println("Setting station to: " + station );
+        this.station = station;
+    }
+
+    public void on() {
+        System.out.println("Turning on Music");
+        //activate hardware...
+    }
+
+    public void off() {
+        System.out.println("Turning off Music");
+        //deactivate hardware
+
+    }
+}