Category Archives: Games

Creating a Blackberry Game – Part 2

package com.synthdreams.GalacticBlast;

import net.rim.device.api.ui.UiApplication;

 * Initial main class that starts the ball rolling
 * UiApplication is extended to provide Blackberry
 * functionality, specifically the Event Dispatcher
 * and Screen pusher
public class GalacticBlast extends UiApplication
    public static void main(String[] args)
        GalacticBlast GalacticBlast = new GalacticBlast();
        // The Blackberry's message pump, handles key
        // presses and system events
    public GalacticBlast()
        // The first thing we do is show the menu screen, defined by the
        // 'Menu' class.  We accomplish this with a call to pushScreen,
        // which puts screens on the stack (Class specified must be a type
        // of screen, such as MainScreen).  The top most screen is the
        // one shown.  Our first one will be the menu, and later the game
        // itself will sit on top of this.  When the game quits, it will
        // pop that screen off the stack and return to the menu screen.
        pushScreen(new Menu());              

Nothing major going on there, simply a place to get started. As we can see, things are immediately handed off to our Menu class, which handles the main menu. It is common functionality to have a main menu where the player can play, save, load, configure, quit, etc.

The Main Menu

Our main menu extends MainScreen, as I wanted just a simple screen with text and buttons, using the built in Blackberry look and feel. However, there is nothing stopping you from using the techniques in the actual gameplay section for displaying more advanced graphics in the menu section. But for this tutorial we have a simple main menu.

The concept behind Blackberry forms is there is a layout manager that occupies a certain amount of screen space, and contains fields that it positions accordingly. You can have multiple layout managers on one screen, each with its own child fields. There are different built in layout managers, and you can make your own custom ones as well. For our main menu, we’ll both use the default built in manager that simply repeats fields in the vertical direction, as well as a custom manager that allows us to specify the exact X,Y coordinates of fields within the layout manager.

Additionally, we’ll be making a special start button that will start the game play by instantiating the Gameplay class and pushing it onto the screen stack (just like our initial class pushed our Menu class onto the screen stack). Also check out our custom fields and field manager that allow us to position fields specifically by X and Y coordinate. Our field manager allows us to specify its height, so we can use it as a simple vertical-space buffer as well.

package com.synthdreams.GalacticBlast;

import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.ui.container.*;

 * The menu class handles showing the main menu and intercepting when the user quits or 
 * begins the game.  If the user presses the button to begin, the Menu class starts
 * the game going.

class Menu extends MainScreen
    GamePlay _game;  // GamePlay handles the action part of the game itself
    int _invokeID; // A handle to our invocation of scanning for when the game ends
    // To add functionality to clicking the button, we need to override the button's
    // trackwheelClick method.  Here we define _startButton as a button with
    // text, positioning, and trackwheelClick we want.
    ButtonField _startButton = new ButtonField("Start Game!", ButtonField.FIELD_HCENTER | ButtonField.FIELD_BOTTOM)

       protected boolean trackwheelClick(int status, int time)
          // If the button is pressed, we create a new GamePlay object
          _game = new GamePlay();
          // Then we push it onto the screen stack.  This then becomes the
          // active screen.  See for notes about pushing
          // screens onto the stack
          // The invokeLater method allows us to continually run a segment of
          // code from outside the GamePlay object.  In this case, we do
          // this to monitor if the gameplay object is active our not.  
          // When the player loses, the object marks itself inactive, at
          // which point we first cancel invoking further, then stop
          // the music from playing, then pop the gameplay screen off
          // the stack so we return to the main menu.
          _invokeID = getApplication().invokeLater(new Runnable()
                public void run()
                    // Check to see if the game is done.
                    if (_game.getActive() == false)
                        // Cancel invoking this piece of code again (normally is invoked
                        // every 500 ms, as specified below)
                        // Kill the music
                        // Pop the gameplay screen off the stack, which returns
                        // the user to the main menu
                        // Display the final score
                        Dialog.inform("Final Score: " + _game.getScore());
                        // We're done with our game object now
                        _game = null;
            , 500,true); // rerun this code every 500ms
          return true;
    // Normally LabelFields are arranged in a very plain order depending on the
    // Layout manager.  They'll repeat vertically with the option of left/center/right
    // justifying.  But sometimes it's nice to be able to specificy exactly in X,Y coordinates
    // where you want the field to go.  This class, in conjunction with the Custom Manager
    // defined below, allows for this
    // Additionally, a "customStyle" is defined for the field.  For our cases, this 
    // is either left to 0 for normal X,Y positioning, set to 1 for X set to 1/8th the total
    // width of the screen, or set to 2 for X+fieldwidth set to 7/8th the total width of the screen.
    // 1/8th and 7/8th for the edge of the text allows for columns to be made, for scores,
    // instructions, or anything else.  More custom centering or something more dynamic
    // could be done with this variable, but its fine for our purposes right now.
    class CustomTextField extends LabelField
       int _xPos, _yPos, _customStyle; // coordinates and style
       // We pass in the coordinates and the custom style
       CustomTextField(String passLabel, int passStyle, int passX, int passY)
              _xPos = passX;
              _yPos = passY;
              _customStyle = passStyle;
       // Getters for position and style
       int getX() { return _xPos; }
       int getY() { return _yPos; }
       int getCustomStyle() { return _customStyle; }
    // Our custom manager is where the magic happens for allowing customtextfields
    // to be placed at any X,Y coordinate.  It reads in the coordinates from the
    // field and places it at those coordinates in the layout.  It will also
    // look at custom layout, and if centered is specified, will ignore the X coordinate
    // and center it at the Y coordinate on the screen.  Additionally, the total height
    // of the manager can be control how much space it takes up regardless of how many
    // fields it contains
    class CustomManager extends Manager
        int _managerHeight; // Total height of the manager
        // Pass in desired height.  Scrolling is turned off in both directions.
        public CustomManager(int passHeight)
            super(Manager.NO_HORIZONTAL_SCROLL | Manager.NO_VERTICAL_SCROLL);
            _managerHeight = passHeight;
        // Sublayout is called automatically to position all the internal fields to this
        // layout.  Its sublayouts job to read in the custom coordinates of each of the fields
        // and place them accordingly.
        protected void sublayout(int width, int height) 
            CustomTextField field;
            // Loop through all the fields contained with the layout manager
            for (int lcv = 0; lcv < getFieldCount(); lcv++)
                //Get the field.
                field = (CustomTextField)getField(lcv);
                //Obtain the custom x and y coordinates for
                //the field and set the position for
                //the field.
                switch (field.getCustomStyle())
                   // Custom style 1 is for the left side of the text to be at 1/8th the width
                   // of the screen
                   case 1:
                        setPositionChild(field, width / 8 , field.getY());
                   // Custom style 2 is for the right side of the text to be at 7/8ths the width
                   // of the screen    
                   case 2:
                        setPositionChild(field, width * 7 / 8 - field.getPreferredWidth(), field.getY());    
                   // Any other custom style gets position strictly from X,Y
                        setPositionChild(field, field.getX(), field.getY());  
                 //Layout the field.
                 layoutChild(field, width, height);

            //Set the manager's dimensions
            setExtent(width, _managerHeight);
        public int getPreferredWidth()
            return Graphics.getScreenWidth();

        public int getPreferredHeight()
            return Graphics.getScreenHeight();

    // Menu constructor
    public Menu()
        // First, turn off scroll bars for this screen in case we accidentally push past the 
        // edge with our fields/whitespace

        // We set the title on the screen
        LabelField title = new LabelField("Galactic Blast Demo", LabelField.FIELD_HCENTER);

        // CustomManagers can also be used just as space buffers.  First we make
        // 20 pixels of space
        getScreen().add(new CustomManager(20));
        // Add some text        
        add(new LabelField("Instructions", LabelField.FIELD_HCENTER));
        // Create another custom manager, but this one we'll use for more than just
        // spacing, we'll actually position some text fields (our instructions)
        CustomManager instManager = new CustomManager(Graphics.getScreenHeight() - 145);                

        // A multi-d array that will store our instruction fields
        CustomTextField instArray[][] = new CustomTextField[3][2];
        instArray[0][0]= new CustomTextField("Trackball", 1, 0, 20);
        instArray[1][0] = new CustomTextField("Space", 1, 0, 40);
        instArray[2][0] = new CustomTextField("Escape", 1, 0, 60);
        instArray[0][1] = new CustomTextField("Move Ship", 2, 0, 20);
        instArray[1][1] = new CustomTextField("Fire Cannon", 2, 0, 40);
        instArray[2][1] = new CustomTextField("Quit Game", 2, 0, 60);

        // Loop through our array and add each field to the layout manager with a different
        // font
        for (int lcv = 0 ; lcv < 3 * 2 ; lcv++)
            instArray[lcv%3][lcv/3].setFont(Font.getDefault().derive(Font.PLAIN, 16));

        // add our button that has the click method overridden
        // Add a buffer of 10 pixels
        getScreen().add(new CustomManager(10));   
        // More text
        LabelField copyrightText = new LabelField("Copyright 2008 Synthetic Dreams", LabelField.FIELD_HCENTER);        
        copyrightText.setFont(Font.getDefault().derive(Font.ITALIC, 14));

At this point, your program should be able to load with a menu screen (well, you’ll have to comment out any mentions of other undefined classes). You should see something like this:

Only with your own text, of course. Now onto Part 3…

Creating a Blackberry Game – Part 1


I’ve used a number of cell phones, and without a doubt RIM’s Blackberry continues to be my favorite by far. Blackberry users will know what I’m talking about – it’s just a fantastic communications device. One of its few shortcomings, though, is its lack of a large game library. Historically, the Blackberry has been targeted at the business market, and its software reflects that. However, more and more of these fantastic cell phones have wound up in the hands of the average consumer, and with good reason. And with that happening, the need for some good, fun games increases. This is where you come in!

The first thing that happens to me whenever I get a new device, after playing around with it of course, is wanting to program it. It’s just the engineer in me popping out. I’ve made a number of Blackberry applications since I first got my 8830, but I wanted to tackle making a game. There are a few resources on the web, but some are targeted at java devices in general, and others are slightly old, so I wanted to put together a good tutorial about creating a Blackberry game for modern devices from start to finish.

This series of tutorials will document creating a simple space fighter game. A completed example of such a game is available on the Synthetic Dreams website, called “Galactic Blast”. The Galactic Blast Demo is a simple example of how easy it is to create a Blackberry game. With the source code documented here, you can go and create your own game, making it as complex as you want. While Galactic Blast is a space fighter, the principle is the same creating any style, from RPG to platform adventure. All development work will be done in Java, and this tutorial assumes you are familiar with this language. Some quick screenshots from the demo:

Getting Started

While strictly speaking it isn’t necessary to own a Blackberry to do Blackberry development, it definitely helps. While the RIM development tools come with a Blackberry emulator that is pretty spot on to the real thing, there are a few areas where the emulator differs (which will be mentioned as we go), and it’s nice to test it out on a real Blackberry. You definitely will need a compiler and IDE. While there are plugins for Visual Studio, they are limited and not as robust as the full Blackberry Java Development Environment provided by RIM. The Blackberry JDE can be obtained for free from RIM here:

At the time of this entry, JDE 4.3.0 was used. This download will come with the JDE as well as a device simulator, and tools to simulate being connected to a wireless network on the simulator. The IDE is fairly nice as well, with some intellisense type method/property/class tips.


Setting up the Project

After starting up the JDE, you’ll want to create a new workspace/project. Name it whatever you’d like. After your project is open, there are a few things you can set immediately. Right click on the project name in the workspace window, and select “Properties”. In the General tab, you can set information such as Title, Version, Vendor, and Description. This will appear when the user downloads your application, as well as the title of the icon on the Blackberry itself.

Right clicking on the project in the workspace window will also allow you to add existing items (such as png/jpegs/midis) to your project or create new ones (java source). For this project, we make use of 6 source files, though only 4 of them contain anything major.

Note – when you’re compiling and running your program, by default it will run on the emulator. When you want to upload it to your Blackberry to test (without going through the hassle of using the Desktop Manager or OTA downloads), the JDE includes a handy utility called the “javaloader” located in the bin directory. There are a number of tasks it can perform, but one of the most useful is simply copying an executable to an actual device. If your device is connected to your computer via USB, use the “-u” option, and then supply the cod file of the program you wish to upload. E.g. “javaloader -u C:\projects\MyProj1\MyProj1.cod”.

Now that you have your project set up, you’re ready to start the actual programming. See you in part 2…