Rival Chess Board and Move Generation Utilities

Installation

Maven

<dependency>
    <groupId>com.netsensia.rivalchess</groupId>
    <artifactId>rivalchess-model</artifactId>
    <version>7.0.4</version>
</dependency>

Gradle

compile group: 'com.netsensia.rivalchess', name: 'rivalchess-model', version: '7.0.4'

Quick Start

Creating a Chess Board

Board board = Board.fromFen("6k1/6p1/1p2q2p/1p5P/1P3RP1/2PK1B2/1r2N3/8 b - g3 5 56");

Generating Legal Moves

List<Move> legalMoves = BoardUtils.getLegalMoves(board);

Making a Move

if (!legalMoves.empty()) {
    Board newBoard = Board.fromMove(board, legalMoves.get(0));
}

Board newBoard = Board.fromMove(board, Move(Square.E2, Square.E4));

Board newBoard = Board.fromMove(board, new Move("e7f8Q"));

Changing Board State

The Board class is immutable. When a move is made, you get a new Board. To change a Board's state without making a move, use the builder.

// Create a builder with the current board as a base
BoardBuilder boardBuilder = Board.builder();

// Modify state as required
boardBuilder.withSquareOccupant(Square.E2, SquareOccupant.NONE);
boardBuilder.withSquareOccupant(Square.E4, SquareOccupant.WP);

// Create new board
Board newBoard = boardBuilder.build();

// Or do it all in one
Board newBoard = Board.builder()
        .withSquareOccupant(Square.E2, SquareOccupant.NONE)
        .withSquareOccupant(Square.E4, SquareOccupant.WP)
        .build()
        
SquareOccupant squareOccupant = newBoard.getSquareOccupant(Square.E4);
Piece piece = squareOccupant.getPiece(); // == Piece.PAWN

The Square and Direction Enums

final Square square = Square.C6;

for (final SliderDirection sliderDirection : SliderDirection.values()) {
    if (square.isValidDirection(sliderDirection)) {
        final Square newSquare = square.fromDirection(sliderDirection);
        ...
    }
}

KnightDirection knightDirection = KnightDirection.EN; // Two steps east, one step north

if (square.isValidDirection(knightDirection)) {
    final Square newSquare = square.fromDirection(knightDirection);
    ...
}

Is Mover In Check?

boolean isCheck = board.isCheck();

Some Other Things

Colour mover = board.getSideToMove();

Colour opponent = mover.opponent();

boolean canCastle = board.isKingSideCastleAvailable(Colour.WHITE);

List<Square> blackKnightSquares = board.getSquaresWithOccupant(SquareOccupant.BN);

boolean isSquareAttacked = board.isSquareAttackedBy(Square.A7, Colour.BLACK)

squareOccupant.WB.ofColour(Colour.BLACK); // == SquareOccupant.BB

History

My first chess program was Rival for DOS, written while listening to Metallica's newly-released Black Album, a few years back in the early nineties. It was pretty good and pretty fast, but not very well written. Rival, that is, not the Black Album.

Next up was Rival for Windows a couple of years later, again in C++ (Borland). Then, Rival for Android was released which used the Rival Chess Engine written in Java.

This library moves the board-management, move-generation and move-making routines into a single component.

It's not a fast as the Rival Chess engine's internal move generation and board manipulation routines. Those use magic bitboards and are at least 20x faster than this library.