feature: Completed component design pattern implementation, testing and respective README (#2153)

* update the explanation in README.md * #556 update initial files * added README to component design pattern * Rearrange the file * Finalize the directory * Add test sample * Update the title for README.md * Update the title for README.md * Update the title for README.md * Update the title for README.md * Finish the component design pattern * Updated comments and docstrings for component DP, added basic tests for App and GameObject java classes. Slight modifications to pom.xml to reflect the test suite introduction. * updated comments/docstrings for all classes - wrote v1 of README.md for component design pattern. This still requires the class diagram sketch. * Update the UML and linked with the README.md * Update the README.md * Remove the additional update method and rearrange the file based on the CheckStyle plugin * Changed the structure based on the code smells feedback from PR * Documentation update - uml * Documentation update - grammar * Updated readme to reflect the use of the LOGGER instead of the system output prints. * Correct the constant name * Uses Lombok to remove getter/setter boilerplate * Rename the constant name * Branch out from master and finish all the review changes * Correct the CheckStyle warning Co-authored-by: Samman Palihapitiya Gamage <u7287889@anu.edu.au> Co-authored-by: SammanPali <110753804+SammanPali@users.noreply.github.com>
2026-05-14 10:58:42 +00:00 · 2022-11-21 00:19:26 +11:00
parent 0a53b23c61
commit 1a14fa4f40
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+package com.iluwatar.component;
+
+import java.awt.event.KeyEvent;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * The component design pattern is a common game design structure. This pattern is often
+ * used to reduce duplication of code as well as to improve maintainability.
+ * In this implementation, component design pattern has been used to provide two game
+ * objects with varying component interfaces (features). As opposed to copying and
+ * pasting same code for the two game objects, the component interfaces allow game
+ * objects to inherit these components from the component classes.
+ *
+ * <p>The implementation has decoupled graphic, physics and input components from
+ * the player and NPC objects. As a result, it avoids the creation of monolithic java classes.
+ *
+ * <p>The below example in this App class demonstrates the use of the component interfaces
+ * for separate objects (player & NPC) and updating of these components as per the
+ * implementations in GameObject class and the component classes.
+ */
+@Slf4j
+public final class App {
+  /**
+   * Program entry point.
+   *
+   * @param args args command line args.
+   */
+  public static void main(String[] args) {
+    final var player = GameObject.createPlayer();
+    final var npc = GameObject.createNpc();
+
+
+    LOGGER.info("Player Update:");
+    player.update(KeyEvent.KEY_LOCATION_LEFT);
+    LOGGER.info("NPC Update:");
+    npc.demoUpdate();
+  }
+}
@@ -0,0 +1,94 @@
+package com.iluwatar.component;
+
+import com.iluwatar.component.component.graphiccomponent.GraphicComponent;
+import com.iluwatar.component.component.graphiccomponent.ObjectGraphicComponent;
+import com.iluwatar.component.component.inputcomponent.DemoInputComponent;
+import com.iluwatar.component.component.inputcomponent.InputComponent;
+import com.iluwatar.component.component.inputcomponent.PlayerInputComponent;
+import com.iluwatar.component.component.physiccomponent.ObjectPhysicComponent;
+import com.iluwatar.component.component.physiccomponent.PhysicComponent;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+/**
+ * The GameObject class has three component class instances that allow
+ * the creation of different game objects based on the game design requirements.
+ */
+@Getter
+@RequiredArgsConstructor
+public class GameObject {
+  private final InputComponent inputComponent;
+  private final PhysicComponent physicComponent;
+  private final GraphicComponent graphicComponent;
+
+  private final String name;
+  private int velocity = 0;
+  private int coordinate = 0;
+
+  /**
+   * Creates a player game object.
+   *
+   * @return player object
+   */
+  public static GameObject createPlayer() {
+    return new GameObject(new PlayerInputComponent(),
+        new ObjectPhysicComponent(),
+        new ObjectGraphicComponent(),
+        "player");
+  }
+
+
+  /**
+   * Creates a NPC game object.
+   *
+   * @return npc object
+   */
+  public static GameObject createNpc() {
+    return new GameObject(
+            new DemoInputComponent(),
+        new ObjectPhysicComponent(),
+        new ObjectGraphicComponent(),
+        "npc");
+  }
+
+  /**
+   * Updates the three components of the NPC object used in the demo in App.java
+   * note that this is simply a duplicate of update() without the key event for
+   * demonstration purposes.
+   *
+   * <p>This method is usually used in games if the player becomes inactive.
+   */
+  public void demoUpdate() {
+    inputComponent.update(this, 0);
+    physicComponent.update(this);
+    graphicComponent.update(this);
+  }
+
+  /**
+   * Updates the three components for objects based on key events.
+   *
+   * @param e key event from the player.
+   */
+  public void update(int e) {
+    inputComponent.update(this, e);
+    physicComponent.update(this);
+    graphicComponent.update(this);
+  }
+
+  /**
+   * Update the velocity based on the acceleration of the GameObject.
+   *
+   * @param acceleration the acceleration of the GameObject
+   */
+  public void updateVelocity(int acceleration) {
+    this.velocity += acceleration;
+  }
+
+
+  /**
+   * Set the c based on the current velocity.
+   */
+  public void updateCoordinate() {
+    this.coordinate += this.velocity;
+  }
+}
@@ -0,0 +1,10 @@
+package com.iluwatar.component.component.graphiccomponent;
+
+import com.iluwatar.component.GameObject;
+
+/**
+ * Generic GraphicComponent interface.
+ */
+public interface GraphicComponent {
+  void update(GameObject gameObject);
+}
@@ -0,0 +1,21 @@
+package com.iluwatar.component.component.graphiccomponent;
+
+import com.iluwatar.component.GameObject;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * ObjectGraphicComponent class mimics the graphic component of the Game Object.
+ */
+@Slf4j
+public class ObjectGraphicComponent implements GraphicComponent {
+
+  /**
+   * The method updates the graphics based on the velocity of gameObject.
+   *
+   * @param gameObject the gameObject instance
+   */
+  @Override
+  public void update(GameObject gameObject) {
+    LOGGER.info(gameObject.getName() + "'s current velocity: " + gameObject.getVelocity());
+  }
+}
@@ -0,0 +1,28 @@
+package com.iluwatar.component.component.inputcomponent;
+
+import com.iluwatar.component.GameObject;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Take this component class to control player or the NPC for demo mode.
+ * and implemented the InputComponent interface.
+ *
+ * <p>Essentially, the demo mode is utilised during a game if the user become inactive.
+ * Please see: http://gameprogrammingpatterns.com/component.html
+ */
+@Slf4j
+public class DemoInputComponent implements InputComponent {
+  private static final int WALK_ACCELERATION = 2;
+
+  /**
+   * Redundant method in the demo mode.
+   *
+   * @param gameObject the gameObject instance
+   * @param e          key event instance
+   */
+  @Override
+  public void update(GameObject gameObject, int e) {
+    gameObject.updateVelocity(WALK_ACCELERATION);
+    LOGGER.info(gameObject.getName() + " has moved right.");
+  }
+}
@@ -0,0 +1,10 @@
+package com.iluwatar.component.component.inputcomponent;
+
+import com.iluwatar.component.GameObject;
+
+/**
+ * Generic InputComponent interface.
+ */
+public interface InputComponent {
+  void update(GameObject gameObject, int e);
+}
@@ -0,0 +1,38 @@
+package com.iluwatar.component.component.inputcomponent;
+
+import com.iluwatar.component.GameObject;
+import java.awt.event.KeyEvent;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * PlayerInputComponent is used to handle user key event inputs,
+ * and thus it implements the InputComponent interface.
+ */
+@Slf4j
+public class PlayerInputComponent implements InputComponent {
+  private static final int WALK_ACCELERATION = 1;
+
+  /**
+   * The update method to change the velocity based on the input key event.
+   *
+   * @param gameObject the gameObject instance
+   * @param e          key event instance
+   */
+  @Override
+  public void update(GameObject gameObject, int e) {
+    switch (e) {
+      case KeyEvent.KEY_LOCATION_LEFT:
+        gameObject.updateVelocity(-WALK_ACCELERATION);
+        LOGGER.info(gameObject.getName() + " has moved left.");
+        break;
+      case KeyEvent.KEY_LOCATION_RIGHT:
+        gameObject.updateVelocity(WALK_ACCELERATION);
+        LOGGER.info(gameObject.getName() + " has moved right.");
+        break;
+      default:
+        LOGGER.info(gameObject.getName() + "'s velocity is unchanged due to the invalid input");
+        gameObject.updateVelocity(0);
+        break; // incorrect input
+    }
+  }
+}
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+package com.iluwatar.component.component.physiccomponent;
+
+import com.iluwatar.component.GameObject;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Take this component class to update the x coordinate for the Game Object instance.
+ */
+@Slf4j
+public class ObjectPhysicComponent implements PhysicComponent {
+
+  /**
+   * The method update the horizontal (X-axis) coordinate based on the velocity of gameObject.
+   *
+   * @param gameObject the gameObject instance
+   */
+  @Override
+  public void update(GameObject gameObject) {
+    gameObject.updateCoordinate();
+    LOGGER.info(gameObject.getName() + "'s coordinate has been changed.");
+  }
+}
@@ -0,0 +1,10 @@
+package com.iluwatar.component.component.physiccomponent;
+
+import com.iluwatar.component.GameObject;
+
+/**
+ * Generic PhysicComponent interface.
+ */
+public interface PhysicComponent {
+  void update(GameObject gameObject);
+}
@@ -0,0 +1,17 @@
+package com.iluwatar.component;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+/**
+ * Tests App class : src/main/java/com/iluwatar/component/App.java
+ * General execution test of the application.
+ */
+class AppTest {
+
+    @Test
+    void shouldExecuteComponentWithoutException() {
+        assertDoesNotThrow(() -> App.main(new String[]{}));
+    }
+}
@@ -0,0 +1,71 @@
+package com.iluwatar.component;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.awt.event.KeyEvent;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Tests GameObject class.
+ * src/main/java/com/iluwatar/component/GameObject.java
+ */
+@Slf4j
+class GameObjectTest {
+    GameObject playerTest;
+    GameObject npcTest;
+    @BeforeEach
+    public void initEach() {
+        //creates player & npc objects for testing
+        //note that velocity and coordinates are initialised to 0 in GameObject.java
+        playerTest = GameObject.createPlayer();
+        npcTest = GameObject.createNpc();
+    }
+
+    /**
+     * Tests the create methods - createPlayer() and createNPC().
+     */
+    @Test
+    void objectTest(){
+        LOGGER.info("objectTest:");
+        assertEquals("player",playerTest.getName());
+        assertEquals("npc",npcTest.getName());
+    }
+
+    /**
+     * Tests the input component with varying key event inputs.
+     * Targets the player game object.
+     */
+    @Test
+    void eventInputTest(){
+        LOGGER.info("eventInputTest:");
+        playerTest.update(KeyEvent.KEY_LOCATION_LEFT);
+        assertEquals(-1, playerTest.getVelocity());
+        assertEquals(-1, playerTest.getCoordinate());
+
+        playerTest.update(KeyEvent.KEY_LOCATION_RIGHT);
+        playerTest.update(KeyEvent.KEY_LOCATION_RIGHT);
+        assertEquals(1, playerTest.getVelocity());
+        assertEquals(0, playerTest.getCoordinate());
+
+        LOGGER.info(Integer.toString(playerTest.getCoordinate()));
+        LOGGER.info(Integer.toString(playerTest.getVelocity()));
+
+        GameObject p2 = GameObject.createPlayer();
+        p2.update(KeyEvent.KEY_LOCATION_LEFT);
+        //in the case of an unknown, object stats are set to default
+        p2.update(KeyEvent.KEY_LOCATION_UNKNOWN);
+        assertEquals(-1, p2.getVelocity());
+    }
+
+    /**
+     * Tests the demo component interface.
+     */
+    @Test
+    void npcDemoTest(){
+        LOGGER.info("npcDemoTest:");
+        npcTest.demoUpdate();
+        assertEquals(2, npcTest.getVelocity());
+        assertEquals(2, npcTest.getCoordinate());
+    }
+}