Ready-to-run Java projects for students, packaged for JuiceMind's free browser IDE.
Just looking for short practice problems? The single-file exercises — printing, loops, recursion, data structures — live in EXERCISES.md. Those are copy-and-paste, no zip needed. Everything below is the bigger graphical projects.
Nothing to install — no JDK, no Eclipse, no downloads beyond a single .zip. Works on
Chromebooks, school laptops, and tablets. Each project is a complete, working starting
point that students are meant to extend.
1. Download the project .zip from the table below.
2. Go to play.juicemind.com/dashboard/code-sandbox and sign in (a free account is fine).
3. Click + Create New Sandbox.
- Give it a name (for example,
Tower Defense) - Under Choose Programming Language, select Java
- Click 🚀 Create Sandbox
4. Open the file explorer — the folder icon in the top-left corner.
5. Click the ⋮ button next to the word Files, then choose Upload zip.
6. Pick the .zip you downloaded, then click Override Project Files when asked.
(This replaces the "Hello world" starter, which is why you want a fresh sandbox.)
7. Press the blue ▶ Run button.
The game window appears in the display panel on the right. If it's cut off, collapse the file explorer, or use the Auto-resize / Fixed size toggle in the bottom-right corner.
| Project | Download | Try it live | What's in it |
|---|---|---|---|
| Tower Defense | TowerDefense.zip | Open sandbox | Tile-based map loaded from a text file, animated enemy that walks the path, a tower that fires bullets. Uses the ACM graphics library. |
| Tic Tac Toe | TicTacToe.zip | Open sandbox | Play X against a computer opponent that blocks you and takes a win when it sees one. Plain Java Swing — no extra library. |
| Space Invaders — starter | SpaceInvaders-Starter.zip | Open sandbox | Your ship, one enemy, click to shoot. Deliberately unfinished: enemies fly off-screen, no rows, no enemy fire. Marked IMPROVE THIS in the code. Uses ACM. |
| Space Invaders — finished | SpaceInvaders-Finished.zip | Open sandbox | The completed game: rows of bouncing enemies, a mothership, bunkers, enemy fire, multiple bullet types, and Game Over. Uses ACM. |
| Game of Life — starter | GameOfLife-Starter.zip | Open sandbox | Conway's Game of Life with the rules left out. Click cells to draw a starting pattern, then press Start. doStep and countNeighbors are marked YOUR CODE HERE. Plain Java Swing. |
| Game of Life — finished | GameOfLife-Finished.zip | Open sandbox | The completed simulation: draw a pattern, press Start, and watch it evolve. Gliders travel. Neighbour counting wraps around the edges. Plain Java Swing. |
| Snake — starter | Snake-Starter.zip | Open sandbox | Classic Snake with the movement left out. The board, apple and score all work; moveSnakeCheckApple, checkBounds, checkOverlap and snakeToGrid are marked YOUR CODE HERE. Plain Java Swing. |
| Snake — finished | Snake-Finished.zip | Open sandbox | The completed game: steer with the arrow keys, eat apples to grow and score, and it's Game Over if you hit a wall or your own tail. Plain Java Swing. |
| Sudoku Solver — starter | Sudoku-Starter.zip | Open sandbox | A constraint-solver skeleton. The puzzle loads from boards/board1.txt and every unsolved square draws the digits still possible for it. isSolved() and onePass() are marked complete this. Uses ACM. |
| Pacman — starter | Pacman-Starter.zip | Open sandbox | The maze, the dots and Pac-Man himself all draw correctly, but he can't move yet. nextImage(), move() and the turning logic are marked TO DO. No ghosts. Uses ACM. |
| Pacman — finished | Pacman-Finished.zip | Open sandbox | The full game: click to start, arrow keys to steer, four ghosts (two wander, two hunt you), power pellets that turn them blue, and a dot counter. Uses ACM. |
| War | War.zip | Open sandbox | The card game. Press Flip Card to play a round; a tie starts a war with three face-down cards each. Real card artwork, a shuffled Deck, and separate Pile and Player classes. Plain Java Swing. |
| Graphics Programs | GraphicsPrograms.zip | Open sandbox | Eleven small ACM drawing programs in one sandbox — seven finished examples (robot face, checkerboard, pyramid, recursive squares, bouncing ball, random art) and four with work left to do (Target, Row of Bricks, Random Art, Animation Pattern Matching). Main.java is a switchboard: uncomment the one you want. Includes a Graphics commands.txt cheat sheet. |
| Breakout — starter | Breakout-Starter.zip | Open sandbox | The classic brick-breaker, with every constant defined (paddle size, brick rows, ball radius) and run() empty. Build the bricks, the paddle, and the bouncing ball yourself. Uses ACM. |
| Breakout — finished | Breakout-Finished.zip | Open sandbox | The completed game: eight rows of coloured bricks, a mouse-controlled paddle, three lives, a score, and a bounce sound. Uses ACM. |
| UFO Game | UfoGame.zip | Open sandbox | A small finished arcade game — shoot the UFO before it lands. A compact example of animation, mouse input and collision detection in about 150 lines. Uses ACM. |
| Yahtzee — starter | Yahtzee-Starter.zip | Open sandbox | The dice game. It asks how many players and their names, then draws the full scorecard and five dice — playGame() is where you take over: roll, let the player re-roll, and score each category. Uses ACM plus yahtzeelib.jar for the board. |
| Memory | Memory.zip | Open sandbox | Pick a theme, then match 12 pairs on a 6x4 grid of face-down cards. A working game with room to grow: there's no score, no move counter, and nothing happens when you find the last pair. Uses ACM. |
| Checkers — starter | Checkers-Starter.zip | Open sandbox | The board draws itself and clicking a dark square highlights it in yellow — that's all. Moving pieces, taking turns and jumping are yours to write. Plain Java Swing, no extra library. |
| Checkers — finished | Checkers-Finished.zip | Open sandbox | Two-player checkers: click a piece then a square to move it, diagonal jumps capture, and a label tracks whose turn it is. No kings and no multi-jumps yet — good places to keep going. Plain Java Swing. |
| Hangman — starter | Hangman-Starter.zip | Open sandbox | The classic CS106A assignment, and the emptiest starter here — run(), reset(), displayWord() and noteIncorrectGuess() are all You fill this in. It runs to a blank console, which is correct. The scaffold measurements and a 100k-word lexicon are provided. Uses ACM. |
| ImageShop — starter | ImageShop-Starter.zip | Open sandbox | A working photo editor with every filter missing. The whole interface — load, save, and twelve buttons — is built; ImageShopAlgorithms.java has eight // TODO methods: rotate, flip, negative, green screen, blur, crop and equalize. Eleven sample images included. Uses ACM plus Stanford's spl.jar. |
Note on the "Try it live" links: these open a JuiceMind sandbox that anyone can edit. Do not make changes! To get your own editable copy, follow the upload steps above.
The main class must be called Main. JuiceMind always runs Main.java, no matter what
else is in the project. Where a project's "real" main class has a different name, you'll find
a small Main.java that just launches it:
public class Main {
public static void main(String[] args) {
new TowerDefense().start(args);
}
}Leave that file alone and edit the real class instead.
acm.jar is already included where a project needs it. This is Stanford's ACM graphics
library (GraphicsProgram, GImage, GRect, GOval, and friends). JuiceMind automatically
puts any .jar in the project folder on the classpath — no configuration required.
Folders matter. Some projects load images and level files by relative path, like
src/resources/grass.png. That's why these are distributed as zips: uploading files one at a
time can't recreate folders, and the project won't find its artwork.
JuiceMind currently runs Java 17. The ACM library is built on the old Applet API, which
was removed in Java 24 — so if JuiceMind upgrades that far in the future, ACM-based projects
will need replacing. Java-only projects are unaffected. You can check the version yourself
with java -version in the sandbox's Shell tool. Pacman and Breakout also use
java.applet.AudioClip for their sound effects, so they print deprecation warnings when they
compile — those are normal and the games run fine.
Package the zip so that it unpacks like this:
Main.java <- launcher, or the real main class named Main
YourClass.java <- all .java files at the TOP level
OtherClass.java
acm.jar <- only if the project uses ACM
src/resources/... <- keep any folders the code references by path
src/levels/...
Java files go at the top level because JuiceMind compiles and runs from the project root.
Don't include Eclipse's bin/, .classpath, .project, .settings, or .DS_Store —
they're just noise, and a stray duplicate .java under bin/ will break the build with a
duplicate class error.
If a demo sandbox gets edited. The "Try it live" sandboxes are publicly editable, so
anyone can change what the next visitor sees. If one gets scribbled on, create a fresh
sandbox, upload that project's .zip again, and swap the link in the table above. The zips
in this repo are the source of truth — the sandboxes are only previews of them.