Refactored the Invaders class to keep things simple. The main change …

…involved moving the next level logic into the game screen class. This way students can focus on the if statements in the Invaders.run loop and won't have to worry about much else.

src/engine/Constants.java

@@ -0,0 +1,9 @@
+package engine;
+
+/**
+ * Created by Ryan on 7/28/2015.
+ */
+public class Constants {
+    /** Max lives. */
+    public static final int MAX_LIVES = 3;
+}

src/engine/DrawManager.java

@@ -82,8 +82,8 @@ public enum SpriteType {
 	 * Private constructor.
 	 */
 	private DrawManager() {
-		fileManager = Core.getFileManager();
-		logger = Core.getLogger();
+		fileManager = Main.getFileManager();
+		logger = Main.getLogger();
 		logger.info("Started loading resources.");
 
 		try {

src/engine/FileManager.java

@@ -42,7 +42,7 @@ public final class FileManager {
 	 * private constructor.
 	 */
 	private FileManager() {
-		logger = Core.getLogger();
+		logger = Main.getLogger();
 	}
 
 	/**

src/engine/Frame.java

@@ -43,7 +43,7 @@ public Frame(final int width, final int height) {
 		this.height = height - insets.top + insets.bottom;
 		setTitle("Invaders");
 
-		addKeyListener(Core.getInputManager());
+		addKeyListener(Main.getInputManager());
 	}
 
 	/**
@@ -54,14 +54,14 @@ public Frame(final int width, final int height) {
 	 * @return Return code of the finished screen.
 	 */
 	public final ScreenType setScreen(final Screen screen) {
-		Core.getLogger().info("Starting " + screen.getScreenType() + " " + Core.WIDTH + "x" + Core.HEIGHT +
-				 " at " + Core.FPS + " fps.");
+		Main.getLogger().info("Starting " + screen.getScreenType() + " " + Main.WIDTH + "x" + Main.HEIGHT +
+				 " at " + Main.FPS + " fps.");
 
 		currentScreen = screen;
 		currentScreen.initialize();
 		ScreenType nextScreen = currentScreen.run();
 
-		Core.getLogger().info("Closing " + screen.getScreenType() + ".");
+		Main.getLogger().info("Closing " + screen.getScreenType() + ".");
 
 		return nextScreen;
 	}

src/engine/GameState.java

@@ -46,16 +46,25 @@ public GameState(final int level, final int score,
 	/**
 	 * @return the level
 	 */
-	public final int getLevel() {
-		return level;
-	}
+	public final int getLevel() {return level; }
+
+	/**
+	 * Sets a new level
+	 * @param newLevel
+	 */
+	public final void setLevel(int newLevel) { this.level = newLevel; }
 
 	/**
 	 * @return the score
 	 */
-	public final int getScore() {
-		return score;
-	}
+	public final int getScore() { return score;	}
+
+	/**
+	 * Sets a new score
+	 * @param newScore
+	 * @return
+	 */
+	public final void setScore(int newScore) { this.score = newScore; }
 
 	/**
 	 * @return the livesRemaining
@@ -64,12 +73,22 @@ public final int getLivesRemaining() {
 		return livesRemaining;
 	}
 
+	/**
+	 * Set new lives remaining
+	 * @param newLivesRemaining
+	 */
+	public final void setLivesRemaining(int newLivesRemaining) { this.livesRemaining = newLivesRemaining; }
+
 	/**
 	 * @return the bulletsShot
 	 */
-	public final int getBulletsShot() {
-		return bulletsShot;
-	}
+	public final int getBulletsShot() { return bulletsShot; }
+
+	/**
+	 * Set bullets shot
+	 * @param bulletsShot
+	 */
+	public void setBulletsShot(int bulletsShot) { this.bulletsShot = bulletsShot; }
 
 	/**
 	 * @return the shipsDestroyed
@@ -78,4 +97,10 @@ public final int getShipsDestroyed() {
 		return shipsDestroyed;
 	}
 
+	/**
+	 * Set ships destroyed
+	 * @param shipsDestroyed
+	 */
+	public void setShipsDestroyed(int shipsDestroyed) { this.shipsDestroyed = shipsDestroyed; }
+
 }

src/engine/Invaders.java

@@ -0,0 +1,57 @@
+package engine;
+
+import screen.*;
+
+import java.util.List;
+
+/**
+ * Created by Ryan on 7/28/2015.
+ */
+public class Invaders {
+
+    /**
+     * Start running the game
+     */
+    public static void run(Frame frame) {
+        // Get the size of the frame
+        int width = frame.getWidth();
+        int height = frame.getHeight();
+
+        // Get a list of levels to play
+        List<GameSettings> levelSettings = Levels.getLevels();
+
+        // Hold on to all of the game's information
+        GameState gameState;
+
+        // The current screen
+        // Empty by default
+        Screen currentScreen;
+
+        // Start at the title screen
+        ScreenType nextScreen = ScreenType.TitleScreen;
+
+        while (nextScreen != ScreenType.EndGame) {
+            // Reset the game's state each time the game starts over
+            gameState = new GameState(1, 0, Constants.MAX_LIVES, 0, 0);
+
+            if(nextScreen == ScreenType.TitleScreen) {
+                // Main menu.
+                currentScreen = new TitleScreen(width, height, Main.FPS);
+                nextScreen = frame.setScreen(currentScreen);
+            }
+            else if (nextScreen == ScreenType.GameScreen) {
+                currentScreen = new GameScreen(gameState, levelSettings, width, height, Main.FPS);
+                frame.setScreen(currentScreen);
+
+                currentScreen = new ScoreScreen(width, height, Main.FPS, gameState);
+                nextScreen = frame.setScreen(currentScreen);
+            }
+            else if (nextScreen == ScreenType.HighScroreScreen) {
+                // High scores.
+                currentScreen = new HighScoreScreen(width, height, Main.FPS);
+                nextScreen = frame.setScreen(currentScreen);
+            }
+
+        }
+    }
+}

src/engine/Core.java → src/engine/Main.java

@@ -1,6 +1,5 @@
 package engine;
 
-import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.ConsoleHandler;
 import java.util.logging.FileHandler;
@@ -20,30 +19,18 @@
  * @author <a href="mailto:[email protected]">Roberto Izquierdo Amo</a>
  * 
  */
-public final class Core {
-
+public final class Main {
 	/** Width of current screen. */
 	public static final int WIDTH = 448;
 	/** Height of current screen. */
 	public static final int HEIGHT = 520;
 	/** Max fps of current screen. */
 	public static final int FPS = 60;
 
-	/** Max lives. */
-	private static final int MAX_LIVES = 3;
-	/** Levels between extra life. */
-	private static final int EXTRA_LIFE_FRECUENCY = 3;
-	/** Total number of levels. */
-	private static final int NUM_LEVELS = 7;
-
 	/** Frame to draw the screen on. */
 	private static Frame frame;
-	/** Screen currently shown. */
-	private static Screen currentScreen;
-	/** Difficulty settings list. */
-	private static List<GameSettings> gameSettings;
 	/** Application logger. */
-	private static final Logger LOGGER = Logger.getLogger(Core.class
+	private static final Logger LOGGER = Logger.getLogger(Main.class
 			.getSimpleName());
 	/** Logger handler for printing to disk. */
 	private static Handler fileHandler;
@@ -78,81 +65,19 @@ public static void main(final String[] args) {
 
 		frame = new Frame(WIDTH, HEIGHT);
 		DrawManager.getInstance().setFrame(frame);
-		int width = frame.getWidth();
-		int height = frame.getHeight();
 
 		// Run the game
-		run(width, height);
+		Invaders.run(frame);
 
 		fileHandler.flush();
 		fileHandler.close();
 		System.exit(0);
 	}
 
-	/**
-	 * Start running the game
-	 * @param width
-	 * @param height
-	 */
-	public static void run(int width, int height) {
-		// Get a list of levels to play
-		gameSettings = Levels.getLevels();
-
-		// Hold on to all of the game's information
-		GameState gameState;
-
-		// Start at the title screen
-		ScreenType nextScreen = ScreenType.TitleScreen;
-
-		do {
-			// Reset the game's state each time the game starts over
-			gameState = new GameState(1, 0, MAX_LIVES, 0, 0);
-
-			if(nextScreen == ScreenType.TitleScreen) {
-				// Main menu.
-				currentScreen = new TitleScreen(width, height, FPS);
-				nextScreen = frame.setScreen(currentScreen);
-			}
-			else if (nextScreen == ScreenType.GameScreen) {
-				// Game & score.
-				do {
-					// One extra life every few levels.
-					boolean bonusLife = gameState.getLevel()
-							% EXTRA_LIFE_FRECUENCY == 0
-							&& gameState.getLivesRemaining() < MAX_LIVES;
-
-					currentScreen = new GameScreen(gameState,
-							gameSettings.get(gameState.getLevel() - 1),
-							bonusLife, width, height, FPS);
-					frame.setScreen(currentScreen);
-
-					gameState = ((GameScreen) currentScreen).getGameState();
-
-					gameState = new GameState(gameState.getLevel() + 1,
-							gameState.getScore(),
-							gameState.getLivesRemaining(),
-							gameState.getBulletsShot(),
-							gameState.getShipsDestroyed());
-
-				} while (gameState.getLivesRemaining() > 0
-						&& gameState.getLevel() <= NUM_LEVELS);
-
-				currentScreen = new ScoreScreen(width, height, FPS, gameState);
-				nextScreen = frame.setScreen(currentScreen);
-			}
-			else if (nextScreen == ScreenType.HighScroreScreen) {
-				// High scores.
-				currentScreen = new HighScoreScreen(width, height, FPS);
-				nextScreen = frame.setScreen(currentScreen);
-			}
-
-		} while (nextScreen != ScreenType.EndGame);
-	}
-
 	/**
 	 * Constructor, not called.
 	 */
-	private Core() {
+	private Main() {
 
 	}
 

src/entity/EnemyShip.java

@@ -3,7 +3,7 @@
 import java.awt.Color;
 
 import engine.Cooldown;
-import engine.Core;
+import engine.Main;
 import engine.DrawManager.SpriteType;
 
 /**
@@ -45,7 +45,7 @@ public EnemyShip(final int positionX, final int positionY,
 		super(positionX, positionY, 12 * 2, 8 * 2, Color.WHITE);
 
 		this.spriteType = spriteType;
-		this.animationCooldown = Core.getCooldown(500);
+		this.animationCooldown = Main.getCooldown(500);
 		this.isDestroyed = false;
 
 		switch (this.spriteType) {

src/entity/EnemyShipFormation.java

@@ -9,7 +9,7 @@
 
 import screen.Screen;
 import engine.Cooldown;
-import engine.Core;
+import engine.Main;
 import engine.DrawManager;
 import engine.DrawManager.SpriteType;
 import engine.GameSettings;
@@ -112,8 +112,8 @@ private enum Direction {
 	 *            Current game settings.
 	 */
 	public EnemyShipFormation(final GameSettings gameSettings) {
-		this.drawManager = Core.getDrawManager();
-		this.logger = Core.getLogger();
+		this.drawManager = Main.getDrawManager();
+		this.logger = Main.getLogger();
 		this.enemyShips = new ArrayList<List<EnemyShip>>();
 		this.currentDirection = Direction.RIGHT;
 		this.movementInterval = 0;
@@ -191,7 +191,7 @@ public final void draw() {
 	 */
 	public final void update() {
 		if(this.shootingCooldown == null) {
-			this.shootingCooldown = Core.getVariableCooldown(shootingInterval,
+			this.shootingCooldown = Main.getVariableCooldown(shootingInterval,
 					shootingVariance);
 			this.shootingCooldown.reset();
 		}

src/entity/Ship.java

@@ -4,7 +4,7 @@
 import java.util.Set;
 
 import engine.Cooldown;
-import engine.Core;
+import engine.Main;
 import engine.DrawManager.SpriteType;
 
 /**
@@ -39,8 +39,8 @@ public Ship(final int positionX, final int positionY) {
 		super(positionX, positionY, 13 * 2, 8 * 2, Color.GREEN);
 
 		this.spriteType = SpriteType.Ship;
-		this.shootingCooldown = Core.getCooldown(SHOOTING_INTERVAL);
-		this.destructionCooldown = Core.getCooldown(1000);
+		this.shootingCooldown = Main.getCooldown(SHOOTING_INTERVAL);
+		this.destructionCooldown = Main.getCooldown(1000);
 	}
 
 	/**