maze-solver

Pure-Java maze solving library, built as a .jar and loaded in the browser by CheerpJ from the software_training repo's lesson site.

Constraints (why the build is set up this way)

CheerpJ runs OpenJDK 8 in the browser, so this library has to play by those rules:

1. Java 8 bytecode. The build compiles with --release 8 (maven.compiler.release in pom.xml). Java 9+ syntax (var, List.of, records, switch expressions, text blocks, ...) will fail to load, not just fail to compile elsewhere, so this is enforced at build time, not just documented.
2. Pure computation only. No networking, no threads, no real filesystem, no AWT/Swing. Maze solving is pure by nature, so this should never come up — but if you find yourself reaching for any of those, stop and reconsider.
3. Small. The jar downloads into the browser on first run. There are currently zero runtime dependencies — keep it that way. (Test-only dependencies, like JUnit, never end up in the built jar.) CI fails the build if the jar exceeds a size budget (see .github/workflows/build.yml).
4. One documented public API. See CONTRACT.md for the MazeSolver interface and the N/S/E/W bitmask convention.

Building

mvn verify

Produces target/maze-solver.jar. Requires a JDK capable of --release 8 (any reasonably recent JDK — this was set up against JDK 21/26) and Maven.

CI (.github/workflows/build.yml) additionally verifies, on every push:

• every .class file in the jar has bytecode major version 52 (Java 8)
• the jar is under the size budget

Project layout

The student-facing API is a set of interfaces plus the concrete GridMaze that reads the bitmask so students never have to.

src/main/java/com/frc2713/mazesolver/
  Direction.java          enum — UP/DOWN/LEFT/RIGHT, with bit()/opposite()/turns
  Cell.java               interface — one square; wall(Direction) queries
  Robot.java              interface — walks the maze; readWallSensor/drive/facing
  Maze.java               interface — the maze, hands out Cells and a Robot
  GridMaze.java           concrete Maze built from an int[][] (the site's entry point)
  GridRobot/GridCell.java the Robot/Cell a GridMaze returns
  MazeSolver.java         interface — a batch solver: int[][] solve(int[][])
  DefaultMazeSolver.java  shipped MazeSolver (breadth-first, shortest path)
src/test/java/...         unit tests

Students drive a Robot (from new GridMaze(grid).robot()) with readWallSensor(Direction) / drive(Direction) and never touch a bitmask. See CONTRACT.md for the full API contract shared with the lesson site.