Welcome to JSnake!

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Please be patient! This applet may take some time to load depending on network conditions. Please note that it you should limit the size of the playing board based on how much memory your machine has. I have set the limit at a 400-row by 400-column board. At this size, my Pentium Pro 200 MHz with 64 MB RAM starts to grind (starts using hard disk space as memory).

When I want to learn a new programming language, I usually try to write something simple so I can quickly finish it, but complicated enough for me to try out all or most of the new features. So, I decided to write a Java version of my famous Snake program. This is the third version of this program I have written. The first one was done back in 1990 in Microsoft QuickBasic. The second one was a 32-bit Windows MFC program in Visual C++, and finally this one is done in Java. This is probably the best version of Snake I have written because it is easily distributed over the Internet and is cross platform compatible. Enjoy!

The object of this game is to fill in as many squares as you can without crossing your own path. You may move in any of 8 directions by pressing the arrow buttons using the mouse or the keypad. Make sure Num Lock is on because the program looks for the numbers 1 through 9 to move. You may choose the direction to move, but the distance you move depends on the number that you are moving into. For example, if you move right and there is an 8 there, you will move 8 spaces to the right. Your current location is shown with a green *. The filled locations are shown with a yellow *. If moving in any direction causes you to cross your path, the game is over. A message will appear indicating your loss and the controls will be disabled. You must start a new game at this point.

You can scroll around using the vertical and horizontal scroll bars. You can also locate your position by pressing the Locate position button or by pressing the L key. If you wish to start a new game, you can press the S key or the start game button. A dialog box will show up telling you your options. Press the A key to display the about box. If you want to see a pie chart of your progress, press P or click to pie chart button. The pie chart will be continuously updated as you play.

I recommend Internet Explorer over Navigator because IE has a faster Java VM.

Here are some of the items, issues, and bugs I will address in the future:

• Scroll bars don't work under UNIX. I don't know why, but the scroll bar under the Netscape VM doesn't seem to work well. It tends to disappear for some reason.
• Faster display updates. A lot of time went into getting the screen to refresh faster. I used the double buffer animation technique to eliminate the flicker and smart redraw after each move. I redrew only the portion that needs to be redrawn after each move. However, I am wondering how to redraw only the area that needs to be redrawn when Java issues a paint event. In Windows, the WM_PAINT event passes a RECT structure, so your code knows what to repaint. I have not yet figured out how Java communicates this information to your program. Currently the program redraws the entire board if the event modal causes a repaint. This can be time consuming if you are playing a large board. I want to be able to access the invalidated rectangle. Any Java experts out there that know how to do this?
• Inconsistent behavior. Behavior is slightly different in Netscape, Internet Explorer, and the applet viewer included with the JDK. Java's cross platform capabilities won't be worth much if vendors don't implement the behavior of the virtual machines the same way. Even with this relatively simple program, there are slight differences in the way it behaves under different Java interpreters. For example, clicking the scroll bars gives different results under different Java VM's.
• Keyboard support in dialog boxes. It is really annoying that Java does not include a keyboard interface. After writing many Windows programs, I expect this functionality to come for free.
• Background music. I don't know about this one. I had background music in my first version and most people turned it off. Should I bother putting in music for this one?
• Save and restore game. My first version had the ability to save your game to a disk so you could continue where you left off latter. However, most people used this feature to save their precious high scoring game. If they made a mistake, they could just reload the saved game. I've seen some people get incredibly high scores using this technique. Because of security concerns, Java applets do not allow disk access, so I can not save your game to a disk. However, I can save to memory, so you will be able to save your session and go back to it latter if you screw up. This is sort of like an "undo". This feature was heavily used in previous versions of this game. If enough people start playing this game, I'll code it in. 

Want to see the source code? Here it is! Have fun! You will need the DiagonalDirectionButton class for it to compile.

If you use Visual Café, you may find my DiagonalDirectionButton component useful. It is a slight variation of the DirectionButton that comes with Visual Café, but it allows you to point the arrows in 4 diagonal directions.

Do you have suggestions for improvements? I like to hear them!

Last Revised: May 22, 1997

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Please send email to:leonfu@remus.rutgers.edu, or leonfu@eden.rutgers.edu