tumbleweedgame.java

/* Title: J2ME Games With MIDP2 Authors: Carol Hamer Publisher: Apress ISBN: 1590593820 */

/*
 Title:  J2ME Games With MIDP2
 Authors:  Carol Hamer
 Publisher:  Apress
 ISBN:   1590593820
 */

import javax.microedition.media.*;
import javax.microedition.media.control.*;

import java.util.Random;

import javax.microedition.lcdui.game.*;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

/**
 * This is the main class of the tumbleweed game.
 * 
 * @author Carol Hamer
 */
public class Jump extends MIDlet implements CommandListener {

  //---------------------------------------------------------
  //   commands

  /**
   * the command to end the game.
   */
  private Command myExitCommand = new Command("Exit", Command.EXIT, 99);

  /**
   * the command to start moving when the game is paused.
   */
  private Command myGoCommand = new Command("Go", Command.SCREEN, 1);

  /**
   * the command to pause the game.
   */
  private Command myPauseCommand = new Command("Pause", Command.SCREEN, 1);

  /**
   * the command to start a new game.
   */
  private Command myNewCommand = new Command("Play Again", Command.SCREEN, 1);

  /**
   * The command to start/pause the music. (This command may appear in a menu)
   */
  private Command myMusicCommand = new Command("Music", Command.SCREEN, 2);

  //---------------------------------------------------------
  //   game object fields

  /**
   * the the canvas that all of the game will be drawn on.
   */
  private JumpCanvas myCanvas;

  //---------------------------------------------------------
  //   thread fields

  /**
   * the thread that advances the cowboy.
   */
  private GameThread myGameThread;

  /**
   * The class that plays music if the user wants.
   */
  //private MusicMaker myMusicMaker;
  private ToneControlMusicMaker myMusicMaker;

  /**
   * The thread tha sets tumbleweeds in motion at random intervals.
   */
  private TumbleweedThread myTumbleweedThread;

  /**
   * if the user has paused the game.
   */
  private boolean myGamePause;

  /**
   * if the game is paused because it is hidden.
   */
  private boolean myHiddenPause;

  //-----------------------------------------------------
  //    initialization and game state changes

  /**
   * Initialize the canvas and the commands.
   */
  public Jump() {
    try {
      myCanvas = new JumpCanvas(this);
      myCanvas.addCommand(myExitCommand);
      myCanvas.addCommand(myMusicCommand);
      myCanvas.addCommand(myPauseCommand);
      myCanvas.setCommandListener(this);
    } catch (Exception e) {
      errorMsg(e);
    }
  }

  /**
   * Switch the command to the play again command.
   */
  void setNewCommand() {
    myCanvas.removeCommand(myPauseCommand);
    myCanvas.removeCommand(myGoCommand);
    myCanvas.addCommand(myNewCommand);
  }

  /**
   * Switch the command to the go command.
   */
  private void setGoCommand() {
    myCanvas.removeCommand(myPauseCommand);
    myCanvas.removeCommand(myNewCommand);
    myCanvas.addCommand(myGoCommand);
  }

  /**
   * Switch the command to the pause command.
   */
  private void setPauseCommand() {
    myCanvas.removeCommand(myNewCommand);
    myCanvas.removeCommand(myGoCommand);
    myCanvas.addCommand(myPauseCommand);
  }

  //----------------------------------------------------------------
  //  implementation of MIDlet
  // these methods may be called by the application management
  // software at any time, so we always check fields for null
  // before calling methods on them.

  /**
   * Start the application.
   */
  public void startApp() throws MIDletStateChangeException {
    try {
      if (myCanvas != null) {
        myCanvas.start();
        myCanvas.flushKeys();
        systemStartThreads();
      }
    } catch (Exception e) {
      errorMsg(e);
    }
  }

  /**
   * stop and throw out the garbage.
   */
  public void destroyApp(boolean unconditional)
      throws MIDletStateChangeException {
    try {
      stopThreads();
      myCanvas = null;
      System.gc();
    } catch (Exception e) {
      errorMsg(e);
    }
  }

  /**
   * request the game to pause. This method is called by the application
   * management software, not in response to a user pausing the game.
   */
  public void pauseApp() {
    try {
      if (myCanvas != null) {
        setGoCommand();
        systemPauseThreads();
      }
    } catch (Exception e) {
      errorMsg(e);
    }
  }

  //----------------------------------------------------------------
  //  implementation of CommandListener

  /*
   * Respond to a command issued on the Canvas. (either reset or exit).
   */
  public void commandAction(Command c, Displayable s) {
    try {
      if (c == myGoCommand) {
        myCanvas.removeCommand(myGoCommand);
        myCanvas.addCommand(myPauseCommand);
        myCanvas.flushKeys();
        userStartThreads();
      } else if (c == myPauseCommand) {
        myCanvas.removeCommand(myPauseCommand);
        myCanvas.addCommand(myGoCommand);
        userPauseThreads();
      } else if (c == myNewCommand) {
        myCanvas.removeCommand(myNewCommand);
        myCanvas.addCommand(myPauseCommand);
        System.gc();
        myCanvas.reset();
        myCanvas.flushKeys();
        myHiddenPause = false;
        myGamePause = false;
        startThreads();
      } else if (c == myMusicCommand) {
        if (myMusicMaker != null) {
          myMusicMaker.toggle();
          myCanvas.repaint();
          myCanvas.serviceRepaints();
        }
      } else if ((c == myExitCommand)/* || (c == Alert.DISMISS_COMMAND)*/) {
        try {
          destroyApp(false);
          notifyDestroyed();
        } catch (MIDletStateChangeException ex) {
        }
      }
    } catch (Exception e) {
      errorMsg(e);
    }
  }

  //-------------------------------------------------------
  //  thread methods

  /**
   * start up all of the game's threads. Creates them if necessary. to be
   * called when the user hits the go command.
   */
  private synchronized void userStartThreads() throws Exception {
    myGamePause = false;
    if (!myHiddenPause) {
      startThreads();
    }
  }

  /**
   * start up all of the game's threads. Creates them if necessary. used by
   * showNotify
   */
  synchronized void systemStartThreads() throws Exception {
    myHiddenPause = false;
    if (!myGamePause) {
      startThreads();
    }
  }

  /**
   * start up all of the game's threads. Creates them if necessary. internal
   * version. note: if this were synchronized, whould it cause deadlock?
   */
  private void startThreads() throws Exception {
    if (myGameThread == null) {
      myGameThread = new GameThread(myCanvas);
      myGameThread.start();
    } else {
      myGameThread.resumeGame();
    }
    if (myTumbleweedThread == null) {
      myTumbleweedThread = new TumbleweedThread(myCanvas);
      myTumbleweedThread.start();
    } else {
      myTumbleweedThread.resumeGame();
    }
    if (myMusicMaker == null) {
      myMusicMaker = new ToneControlMusicMaker();
      //myMusicMaker = new MusicMaker();
      myMusicMaker.start();
    } else {
      myMusicMaker.resumeGame();
    }
  }

  /**
   * Pause all of the threads started by this game. to be called when the user
   * hits the pause command.
   */
  synchronized void userPauseThreads() {
    myGamePause = true;
    pauseThreads();
  }

  /**
   * Pause all of the threads started by this game. used by hideNotify
   */
  void systemPauseThreads() {
    myHiddenPause = true;
    pauseThreads();
  }

  /**
   * start up all of the game's threads. Creates them if necessary. internal
   * version. note: if this were synchronized, whould it cause deadlock?
   */
  private void pauseThreads() {
    if (myGameThread != null) {
      myGameThread.pauseGame();
    }
    if (myTumbleweedThread != null) {
      myTumbleweedThread.pauseGame();
    }
    if (myMusicMaker != null) {
      myMusicMaker.pauseGame();
    }
  }

  /**
   * Stop all of the threads started by this game and delete them as they are
   * no longer usable.
   */
  private synchronized void stopThreads() {
    if (myGameThread != null) {
      myGameThread.requestStop();
    }
    if (myTumbleweedThread != null) {
      myTumbleweedThread.requestStop();
    }
    if (myMusicMaker != null) {
      myMusicMaker.requestStop();
    }
    myGameThread = null;
    myTumbleweedThread = null;
    myMusicMaker = null;
  }

  //-------------------------------------------------------
  //  error methods

  /**
   * Converts an exception to a message and displays the message..
   */
  void errorMsg(Exception e) {
    if (e.getMessage() == null) {
      errorMsg(e.getClass().getName());
    } else {
      errorMsg(e.getClass().getName() + ":" + e.getMessage());
    }
  }

  /**
   * Displays an error message alert if something goes wrong.
   */
  void errorMsg(String msg) {
    Alert errorAlert = new Alert("error", msg, null, AlertType.ERROR);
    errorAlert.setCommandListener(this);
    errorAlert.setTimeout(Alert.FOREVER);
    Display.getDisplay(this).setCurrent(errorAlert);
  }

}

/**
 * This class is the display of the game.
 * 
 * @author Carol Hamer
 */

class JumpCanvas extends javax.microedition.lcdui.game.GameCanvas {

  //---------------------------------------------------------
  //   dimension fields
  //  (constant after initialization)

  /**
   * the height of the green region below the ground.
   */
  static final int GROUND_HEIGHT = 32;

  /**
   * a screen dimension.
   */
  static final int CORNER_X = 0;

  /**
   * a screen dimension.
   */
  static final int CORNER_Y = 0;

  /**
   * a screen dimension.
   */
  static int DISP_WIDTH;

  /**
   * a screen dimension.
   */
  static int DISP_HEIGHT;

  /**
   * a font dimension.
   */
  static int FONT_HEIGHT;

  /**
   * the default font.
   */
  static Font FONT;

  /**
   * a font dimension.
   */
  static int SCORE_WIDTH;

  /**
   * The width of the string that displays the time, saved for placement of
   * time display.
   */
  static int TIME_WIDTH;

  /**
   * color constant
   */
  public static final int BLACK = 0;

  /**
   * color constant
   */
  public static final int WHITE = 0xffffff;

  //---------------------------------------------------------
  //   game object fields

  /**
   * a handle to the display.
   */
  private Display myDisplay;

  /**
   * a handle to the MIDlet object (to keep track of buttons).
   */
  private Jump myJump;

  /**
   * the LayerManager that handles the game graphics.
   */
  private JumpManager myManager;

  /**
   * whether or not the game has ended.
   */
  private boolean myGameOver;

  /**
   * the player's score.
   */
  private int myScore = 0;

  /**
   * How many ticks we start with.
   */
  private int myInitialGameTicks = 950;

  /**
   * this is saved to determine if the time string needs to be recomputed.
   */
  private int myOldGameTicks = myInitialGameTicks;

  /**
   * the number of game ticks that have passed.
   */
  private int myGameTicks = myOldGameTicks;

  /**
   * we save the time string to avoid recreating it unnecessarily.
   */
  private static String myInitialString = "1:00";

  /**
   * we save the time string to avoid recreating it unnecessarily.
   */
  private String myTimeString = myInitialString;

  //-----------------------------------------------------
  //    gets/sets

  /**
   * This is called when the game ends.
   */
  void setGameOver() {
    myGameOver = true;
    myJump.userPauseThreads();
  }

  /**
   * @return a handle to the tumbleweed objects.
   */
  Tumbleweed[] getTumbleweeds() {
    return (myManager.getTumbleweeds());