design patterns : command

design-pattern/gof/src/command/after/Button.java

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+package command.after;
+
+import java.util.Stack;
+
+public class Button {
+
+    private Stack<Command> commands = new Stack<>();
+
+    public void press(Command command) {
+        command.execute();
+        commands.push(command);
+    }
+
+    public void undo() {
+        if (!commands.isEmpty()) {
+            Command command = commands.pop();
+            command.undo();
+        }
+    }
+
+    public static void main(String[] args) {
+        Button button = new Button();
+        button.press(new GameStartCommand(new Game()));
+        button.press(new LightOnCommand(new Light()));
+        button.undo();
+        button.undo();
+    }
+}

design-pattern/gof/src/command/after/Command.java

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+package command.after;
+
+public interface Command {
+
+    void execute();
+
+    void undo();
+}

design-pattern/gof/src/command/after/Game.java

@@ -0,0 +1,20 @@
+package command.after;
+
+public class Game {
+
+    private boolean isStarted;
+
+    public void start() {
+        System.out.println("게임을 시작합니다.");
+        this.isStarted = true;
+    }
+
+    public void end() {
+        System.out.println("게임을 종료합니다.");
+        this.isStarted = false;
+    }
+
+    public boolean isStarted() {
+        return isStarted;
+    }
+}

design-pattern/gof/src/command/after/GameEndCommand.java

@@ -0,0 +1,20 @@
+package command.after;
+
+public class GameEndCommand implements Command {
+
+    private Game game;
+
+    public GameEndCommand(Game game) {
+        this.game = game;
+    }
+
+    @Override
+    public void execute() {
+        game.end();
+    }
+
+    @Override
+    public void undo() {
+        new GameStartCommand(this.game).execute();
+    }
+}

design-pattern/gof/src/command/after/GameStartCommand.java

@@ -0,0 +1,20 @@
+package command.after;
+
+public class GameStartCommand implements Command {
+
+    private Game game;
+
+    public GameStartCommand(Game game) {
+        this.game = game;
+    }
+
+    @Override
+    public void execute() {
+        game.start();
+    }
+
+    @Override
+    public void undo() {
+        new GameEndCommand(this.game).execute();
+    }
+}

design-pattern/gof/src/command/after/Light.java

@@ -0,0 +1,20 @@
+package command.after;
+
+public class Light {
+
+    private boolean isOn;
+
+    public void on() {
+        System.out.println("불을 켭니다.");
+        this.isOn = true;
+    }
+
+    public void off() {
+        System.out.println("불을 끕니다.");
+        this.isOn = false;
+    }
+
+    public boolean isOn() {
+        return this.isOn;
+    }
+}

design-pattern/gof/src/command/after/LightOffCommand.java

@@ -0,0 +1,20 @@
+package command.after;
+
+public class LightOffCommand implements Command {
+
+    private Light light;
+
+    public LightOffCommand(Light light) {
+        this.light = light;
+    }
+
+    @Override
+    public void execute() {
+        light.off();
+    }
+
+    @Override
+    public void undo() {
+        new LightOnCommand(this.light).execute();
+    }
+}

design-pattern/gof/src/command/after/LightOnCommand.java

@@ -0,0 +1,21 @@
+package command.after;
+
+public class LightOnCommand implements Command {
+
+    private Light light;
+
+    public LightOnCommand(Light light) {
+        this.light = light;
+    }
+
+    @Override
+    public void execute() {
+        light.on();
+    }
+
+    @Override
+    public void undo() {
+        new LightOffCommand(this.light).execute();
+    }
+
+}

design-pattern/gof/src/command/after/MyApp.java

@@ -0,0 +1,20 @@
+package command.after;
+
+public class MyApp {
+
+    private Command command;
+
+    public MyApp(Command command) {
+        this.command = command;
+    }
+
+    public void press() {
+        command.execute();
+    }
+
+    public static void main(String[] args) {
+        MyApp myApp = new MyApp(new GameStartCommand(new Game()));
+        myApp.press();
+        myApp.press();
+    }
+}

design-pattern/gof/src/command/before/Button.java

@@ -0,0 +1,22 @@
+package command.before;
+
+public class Button {
+
+    private Light light;
+
+    public Button(Light light) {
+        this.light = light;
+    }
+
+    public void press() {
+        light.off();
+    }
+
+    public static void main(String[] args) {
+        Button button = new Button(new Light());
+        button.press();
+        button.press();
+        button.press();
+        button.press();
+    }
+}

design-pattern/gof/src/command/before/Game.java

@@ -0,0 +1,20 @@
+package command.before;
+
+public class Game {
+
+    private boolean isStarted;
+
+    public void start() {
+        System.out.println("게임을 시작합니다.");
+        this.isStarted = true;
+    }
+
+    public void end() {
+        System.out.println("게임을 종료합니다.");
+        this.isStarted = false;
+    }
+
+    public boolean isStarted() {
+        return isStarted;
+    }
+}

design-pattern/gof/src/command/before/Light.java

@@ -0,0 +1,20 @@
+package command.before;
+
+public class Light {
+
+    private boolean isOn;
+
+    public void on() {
+        System.out.println("불을 켭니다.");
+        this.isOn = true;
+    }
+
+    public void off() {
+        System.out.println("불을 끕니다.");
+        this.isOn = false;
+    }
+
+    public boolean isOn() {
+        return this.isOn;
+    }
+}

design-pattern/gof/src/command/before/MyApp.java

@@ -0,0 +1,22 @@
+package command.before;
+
+public class MyApp {
+
+    private Game game;
+
+    public MyApp(Game game) {
+        this.game = game;
+    }
+
+    public void press() {
+        game.start();
+    }
+
+    public static void main(String[] args) {
+        Button button = new Button(new Light());
+        button.press();
+        button.press();
+        button.press();
+        button.press();
+    }
+}