We Keep Coding

Add Specific Object to a Binary Search Tree

I'm looking to add an object called "player" to a binary search tree based on how high the score of the player is, essentially like a scoreboard, but I'm not entirely certain how to add players to the binary tree; I'm curious how to go about writing the method, so I hope this question makes sense.
Here's a part of my BinaryTree class:
import java.util.Iterator;
public class BinaryTree implements Iterable<Player> {
private BinNode root;
public BinaryTree() {
root = null;
}
public boolean isEmpty() {
return root == null;
}
// TODO: add the given player to the binary tree based on the player's game score
public void add(final Player player) {
if (isEmpty())
root = new BinNode(player);
// this is SUUUPER placeholder
} ...
Here's the player class, :
public class Player implements Comparable<Player> {
private String name;
private int score;
private static final int MIN_SCORE = 0;
public Player(final String name, int score) {
this.name = name;
if (score < MIN_SCORE)
this.score = 0;
else
this.score = score;
}
public Player(final String name) {
this(name, MIN_SCORE);
}
public String getName() {
return name;
}
public int getScore() {
return score;
}
#Override
public String toString() {
return name + ": " + score;
}
// TODO: compare player objects based on their scores
#Override
public int compareTo(Player other) {
return score - other.score;// I think this is a step in the right direction???
}
}
Here's my Binary Node class:
public class BinNode {
private Player player;
private BinNode left, right;
public BinNode() {
player = null;
left = right = null;
}
public BinNode(final Player player) {
this.player = player;
left = right = null;
}
public Player getPlayer() {
return player;
}
public BinNode getLeft() {
return left;
}
public BinNode getRight() {
return right;
}
public void setPlayer(final Player data) {
this.player = player;
}
public void setLeft(BinNode left) {
this.left = left;
}
public void setRight(BinNode right) {
this.right = right;
}
#Override
public String toString() {
return player.toString();
}
}

I recommend you not to use your own trees in production, but if you are just learn, then that's fine. To add a new entity to your tree, you have to find a place for it. In this code we search for it by comparing scores of players.
public void add(final Player player){
if (isEmpty()){
root = new BinNode(player);
}
else{
BinNode node = root;
while (true){
if (player.getScore() <= node.getPlayer().getScore()){
if (node.getLeft() == null){
node.getLeft() = new BinNode(player);
return;
}
else{
node = node.getLeft();
}
}
else{
if (node.getRight() == null){
node.getRight() = new BinNode(player);
return;
}
else {
node = node.getRight();
}
}
}
}
}

Chess/Java: "Moved Out Of Check" Check in Java

So I've been working on this chess app for about a week now (a few hours a day)-- and I seem to have hit a snag. All of the pieces move as they should, with collision and all-- I have promotion and castling working, and I can successfully check for being in check.
However, I can't seem to check if a move legally gets out of check. My current approach is to move the piece-- check if the person is still in check, and if not then the move is legal.
It seems that when I do this, however, it doesn't correctly calculate the check after the faux-move.
Any help would be great.
public abstract class Piece {
private Type type = Type.BLANK;
private int locX, locY, preX, preY;
private Player player;
private boolean moved = false;
Piece(Type type, int locX, int locY, Player player) {
this.locX = locX;
this.locY = locY;
this.player = player;
this.type = type;
}
public void movePiece(int x, int y) {
if (player.isTurn()) {
if (isLegalMove(x, y)) {
if (checkCollision(x, y)) {
if (clearsCheck(x, y)) {
preX = locX;
preY = locY;
setLoc(x, y);
specialPreMove(x, y);
moved = true;
Chess.chessBoard.bitBoard[preX][preY] = null;
if (Chess.chessBoard.bitBoard[x][y] != null) {
Chess.chessBoard.bitBoard[x][y].getPlayer().pieces.remove(Chess.chessBoard.bitBoard[x][y]);
}
Chess.chessBoard.bitBoard[x][y] = this;
specialPostMove(x, y);
Chess.chessBoard.getGui().repaint();
Chess.changeTurns();
}
}
}
}
}
protected void specialPreMove(int x, int y) {}
protected void specialPostMove(int x, int y) {}
protected abstract boolean checkCollision(int x, int y);
protected abstract boolean isLegalMove(int x, int y);
private boolean clearsCheck(int x, int y) {
boolean checkCk = false;
preX = locX;
preY = locY;
setLoc(x, y);
Piece locPiece = null;
Chess.chessBoard.bitBoard[preX][preY] = null;
if (Chess.chessBoard.bitBoard[x][y] != null) {
locPiece = Chess.chessBoard.bitBoard[x][y];
Chess.chessBoard.bitBoard[x][y].getPlayer().pieces.remove(Chess.chessBoard.bitBoard[x][y]);
System.out.println("Piece there: " + locPiece);
}
Chess.chessBoard.bitBoard[x][y] = this;
System.out.println(Chess.chessBoard.bitBoard[x][y]);
Chess.chessBoard.getGui().repaint();
Chess.checkCheck();
checkCk = !player.inCheck();
setLoc(preX, preY);
Chess.chessBoard.bitBoard[preX][preY] = this;
if (locPiece != null) {
Chess.chessBoard.bitBoard[x][y] = locPiece;
Chess.chessBoard.bitBoard[x][y].getPlayer().pieces.add(Chess.chessBoard.bitBoard[x][y]);
} else {
Chess.chessBoard.bitBoard[x][y] = null;
}
System.out.println(checkCk);
return checkCk;
}
public ArrayList<Move> getLegalMoves() {
ArrayList<Move> moves = new ArrayList<Move>();
for (int row = 0; row < 8; row++) {
for (int col = 0; col < 8; col++) {
if (isLegalMove(row, col) && checkCollision(row, col)) {
moves.add(new Move(row, col));
}
}
}
return moves;
}
is the piece class, and then the check method
public static void checkCheck() {
for (Move m : player1.getLegalMoves()) {
if (m.getX() == player2.getKing().getLocX()
&& m.getY() == player2.getKing().getLocY()) {
player2.setCheck(true);
System.out.println("IN CHECK PLAYER 2");
break;
}
}
for (Move m : player2.getLegalMoves()) {
if (m.getX() == player1.getKing().getLocX()
&& m.getY() == player1.getKing().getLocY()) {
player1.setCheck(true);
System.out.println("IN CHECK PLAYER 1");
break;
}
}
}
and then here is some other stuff that is useful
public class Player {
private Color color;
private Direction direction;
private boolean turn;
private boolean check = false;
public ArrayList<Piece> pieces = new ArrayList<>();
public Player(Color color, Direction direction) {
this.color = color;
this.turn = false;
this.direction = direction;
}
public ArrayList<Move> getLegalMoves() {
ArrayList<Move> moves = new ArrayList<>();
for (Piece p : pieces) {
for (Move m : p.getLegalMoves()) {
moves.add(m);
}
}
return moves;
}
public Piece getKing() {
for (Piece p : pieces) {
if (p.getType() == Type.KING) {
return p;
}
}
return null;
}

Looks like once you set a player in check you're not setting his status later on to unchecked.
public static void checkCheck() {
boolean isInCheck = false;
for (Move m : player1.getLegalMoves()) {
if (m.getX() == player2.getKing().getLocX()
&& m.getY() == player2.getKing().getLocY()) {
isInCheck = true;
System.out.println("IN CHECK PLAYER 2");
break;
}
}
player2.setCheck(isInCheck);
isInCheck = false;
for (Move m : player2.getLegalMoves()) {
if (m.getX() == player1.getKing().getLocX()
&& m.getY() == player1.getKing().getLocY()) {
isInCheck = true;
System.out.println("IN CHECK PLAYER 1");
break;
}
}
player1.setCheck(isInCheck);
}

Implementing “Check” in a Chess Game

Hello I am new in Java and I have stuck. I am trying to make chess game, I made everything except check and checkmate method, and if you have any suggestions I will be happy to read them. Here is my work till now:
This is the board class where we play the game:
public class Board {
public static final int COLOR_WHITE = 1;
public static final int COLOR_BLACK = 2;
public static PlayingPiece[][] board;
private boolean isFirstMove;
private int color;
public Board() {
this.setBoard(new PlayingPiece[8][8]);
this.isFirstMove = true;
this.initializePieces();
}
// Initialize the chess pieces
public void initializePieces() {
for (int i = 0; i < 8; i++) {
board[1][i] = new Pawn(1, i, COLOR_WHITE);
}
for (int i = 0; i < 8; i++) {
board[6][i] = new Pawn(6, i, COLOR_BLACK);
}
board[0][0] = new Rook(0, 0, COLOR_WHITE);
board[0][7] = new Rook(0, 7, COLOR_WHITE);
board[7][0] = new Rook(7, 0, COLOR_BLACK);
board[7][7] = new Rook(7, 7, COLOR_BLACK);
board[0][1] = new Knight(0, 1, COLOR_WHITE);
board[0][6] = new Knight(0, 6, COLOR_WHITE);
board[7][1] = new Knight(7, 1, COLOR_BLACK);
board[7][6] = new Knight(7, 6, COLOR_BLACK);
board[0][2] = new Officer(0, 2, COLOR_WHITE);
board[0][5] = new Officer(0, 5, COLOR_WHITE);
board[7][2] = new Officer(7, 2, COLOR_BLACK);
board[7][5] = new Officer(7, 5, COLOR_BLACK);
board[0][3] = new Queen(3, 0, COLOR_WHITE);
board[0][4] = new King(4, 0, COLOR_WHITE);
board[7][3] = new Queen(7, 3, COLOR_BLACK);
board[7][4] = new King(7, 4, COLOR_BLACK);
this.printBoard();
}
public boolean play(int color, int fromX, int fromY, int toX, int toY) {
boolean isTrue = false;
// Check if this is the first turn and only white can move
if (isFirstMove && color == COLOR_WHITE) {
isTrue = true;
} else if (isFirstMove && color == COLOR_BLACK) {
return false;
}
// check if player plays 2 times in a raw and if you move the piece from
// current possition
if (color == this.color || (toX == fromX && toY == fromY)) {
return false;
}
isTrue = true;
if (isTrue == true) {
this.isFirstMove = false;
// Check if player plays with his own color
if (((board[fromX][fromY]).getColor() != color)) {
return false;
}
// Check the isLegal movement of every chess piece
if ((board[fromX][fromY]).move(toX, toY)) {
board[toX][toY] = board[fromX][fromY];
board[fromX][fromY] = null;
}
this.printBoard();
}
return isTrue;
}
public PlayingPiece[][] getBoard() {
return board;
}
public void setBoard(PlayingPiece[][] board) {
Board.board = board;
}
This is the Pieces class with all kind of pieces:
package com.chess.www;
public class PlayingPiece {
public static final int COLOR_WHITE = 1;
public static final int COLOR_BLACK = 2;
public static final char BLACK_PAWN = '\u265F';
public static final char BLACK_ROOK = '\u265C';
public static final char BLACK_KNIGHT = '\u265E';
public static final char BLACK_BISHOP = '\u265D';
public static final char BLACK_QUEEN = '\u265B';
public static final char BLACK_KING = '\u265A';
public static final char WHITE_PAWN = '\u2659';
public static final char WHITE_ROOK = '\u2656';
public static final char WHITE_KNIGHT = '\u2658';
public static final char WHITE_BISHOP = '\u2657';
public static final char WHITE_QUEEN = '\u2655';
public static final char WHITE_KING = '\u2654';
public static final char NO_PIECE = ' ';
private int x, y;
private boolean isAlive;
private int color;
private char symbol;
protected PlayingPiece (int newX, int newY, int newColor) {
this.setX(newX);
this.setY(newY);
this.color = newColor;
this.isAlive = true;
}
protected PlayingPiece(int newX, int newY) {
this.setX(newX);
this.setY(newY);
}
protected PlayingPiece() {
}
public int getX() {
return x;
}
public void setY(int y) {
this.y = y;
}
public int getY() {
return y;
}
public void setX(int x) {
this.x = x;
}
protected boolean moveIsLegal (int newX, int newY) {
boolean isLegal = false;
if ((0 <= newX && newX <= 7) && (0 <= newY && newY <= 7)){
isLegal = true;
}
return isLegal;
}
public boolean move (int newX, int newY) {
if (moveIsLegal(newX, newY)) {
setX(newX);
setY(newY);
return true;
}
return false;
}
public int getColor() {
return color;
}
public boolean isAlive() {
return isAlive;
}
public void setAlive(boolean isAlive) {
this.isAlive = isAlive;
}
public char getSymbol() {
return symbol;
}
public void setSymbol(char symbol) {
this.symbol = symbol;
}
}
And here is the King class:
package com.chess.www;
public class King extends PlayingPiece {
public King(int newX, int newY, int color) {
super(newX, newY, color);
if (color == COLOR_BLACK) {
this.setSymbol(BLACK_KING);
} else {
this.setSymbol(WHITE_KING);
}
}
#Override
protected boolean moveIsLegal(int newX, int newY) {
int newPositionX = newX - getX();
int newPositionY = newY - getY();
int checkX = this.getX();
int checkY = this.getY();
if (super.moveIsLegal(newX, newY)) {
if ((Math.abs(newPositionX) == 1) && (newY == getY())) {
while (checkX != newX) {
if (this.isValidTraceX(checkX, newY, newX)) {
return true;
}
if (checkX > newX) {
checkX--;
} else if (this.getX() < newX) {
checkX++;
}
}
} else if ((newX == getX()) && (Math.abs(newPositionY) == 1)) {
while (checkY != newY) {
if (this.isValidTraceY(newX, checkY, newY)) {
return true;
}
if (checkY > newY) {
checkY--;
} else if (this.getY() < newY) {
checkY++;
}
}
} else if ((Math.abs(newPositionY) == 1) == (Math.abs(newPositionX) == 1)) {
while (checkX != newX && checkY != newY) {
if (this.isValidTrace(checkX, checkY, newX, newY)) {
return true;
}
if (checkX > newX) {
checkX--;
} else if (this.getX() < newX) {
checkX++;
}
if (checkY > newY) {
checkY--;
} else if (this.getY() < newY) {
checkY++;
}
}
}
}
return false;
}
public boolean isValidTraceX(int newX, int newY, int lastX) {
boolean isValid = true;
if ((Board.board[newX][newY]) != null) {
isValid = false;
}
if (((Board.board[lastX][newY]) != null)) {
if (Board.board[lastX][newY].getColor() == this.getColor()) {
isValid = false;
} else {
isValid = true;
}
}
return isValid;
}
public boolean isValidTraceY(int newX, int newY, int lastY) {
boolean isValid = true;
if ((Board.board[newX][newY]) != null) {
isValid = false;
}
if (((Board.board[newX][lastY]) != null)) {
if (Board.board[newX][lastY].getColor() == this.getColor()) {
isValid = false;
} else {
isValid = true;
}
}
return isValid;
}
public boolean isValidTrace(int newX, int newY, int lastX, int lastY) {
boolean isValid = true;
if ((Board.board[newX][newY]) != null) {
isValid = false;
}
if (((Board.board[lastX][lastY]) != null)) {
if (Board.board[lastX][lastY].getColor() == this.getColor()) {
isValid = false;
} else {
isValid = true;
}
}
return isValid;
}
}
I want to implement the method for check in board class do you have any suggestions?

The way I would implement would be just a method in the King class called something like, isChecked.
boolean isChecked() {
/* Check straight lines */
for (directions) { // up, down, left and right
for (square in direction) { // square by square from the king and out in the current direction
if (square contains opponent rook or queen)
return true;
else if (square contains friendly piece)
continue;
/* Check diagonals */
for (directions) { // left-up, left-down, right-up and right-down
for (square in direction) { // square by square from the king and out in the current direction
if (square contains opponent bishop or queen)
return true;
else if (square contains friendly piece)
continue;
/* Check pawns */
if (squares where pawns would threaten the king contains pawns)
return true;
/* Check king, this is to find if a square is legal to move to only */
if (squares where a king would threaten the king contains king)
return true;
/* Check knights */
if (squares where knights would threaten the king contains knights)
return true;
Sorry, I haven't really got time to write the entire code now, but the pseudo code should be enough to understand the concept. If you need I could fix it later today.
The principle is just, check every possible way a king can be checked.
If a king is checked and all possible moves are also checked, it is a checkmate.
Hope it helps :)

import java.util.Arrays;
public class KingsChecker {
public static void main(String[] args) {
int n = Integer.parseInt(args[0]);
String[][] chess = new String[n][n];
print(chess,n);
}
public static void print (String[][] chess,int n) {
for(int i = 0; i< chess.length; i++) {
double random = Math.random()*n; //to generate a random number.
for(int j = 0; j < chess[i].length; j++) {
int column = (int)random;
int[] count = new int[n];
chess[i][j]= "+";
count[column]++;
if (count[column]<=1){
chess[i][column]="k";
System.out.print(chess[i][j]);
}
}
System.out.println();
}
}
}

How come this algorithm and class in my game is slowing down the frame rate so much?

I wrote an event system for a game engine I'm working on, which adds en event to a tile in a map which when the player intersects it, it does something. Whatever that something is. In this test case, it loads a new map.
The problem is that the frame rate when starting the game is about 30 right up until I begin the event by walking over it, which starts the event and brings the fps up to about 60.
EDIT: it seems that this issue only popped up after I added events. However, I added another similar warping event to see if the fps dropped even more, it didn't. And after I finished the first event, the fps went to normal and I still used the second event fine.
Here is the event class:
public class Event {
//Warping variables
private int newX, newY;
private Map _map, _mapOverlay;
private String eventType;
private String _name;
public Event(String name, String type) {
_name = name;
eventType = type;
}
public void setWarp(Map map, Map overlay, int x, int y) {
_map = map;
_mapOverlay = overlay;
newX = x;
newY = y;
}
public Map getMap() { return _map; }
public Map getOverlay() { return _mapOverlay; }
public int getNewX() { return newX; }
public int getNewY() { return newY; }
public String getEventType() { return eventType; }
public String getname() { return _name; }
}
This is the algorithm that is called when a warp event is collided with:
if(spr.spriteType() == "player" && tile.hasEvent()) {
if(tile.event().getEventType() == "warp") {
tiles().clear();
currentMap = tile.event().getMap();
currentOverlay = tile.event().getOverlay();
for(int i = 0; i < currentMap.getWidth() * currentMap.getHeight(); i++){
tiles().add(currentMap.accessTile(i));
tiles().add(currentOverlay.accessTile(i));
}
playerX = tile.event().getNewX();
playerY = tile.event().getNewY();
tile.endEvent();
}
}
This is the section inside of the tile class which contains methods that have to do with adding an event.
public void addEvent(Event event) {
this.event = event;
hasEvent = true;
}
public Event event() { return event; }
public boolean hasEvent() { return hasEvent; }
public void endEvent() {
event = null;
hasEvent = false;
}
Lastly, here are the three lines used to add an event to an existing tile in a map:
warp1 = new Event("testWarp", "warp");
warp1.setWarp(city, cityOverlay, -200, 0);
city.accessTile(204).addEvent(warp1);

Rideable Controllable Entity minecraft

I am having a problem making an entity controllable in minecraft. I am are able to mount it, and it will move, but a few seconds after you move it, it just jumps back to where it was before you moved it. Here is my Entity class:
package net.minecraft.src;
public class mod_EntityMech extends EntityMob // this to make mob hostile
{
public boolean stationary;
public mod_EntityMech(World par1World)
{
super(par1World);
isImmuneToFire = false;
}
public int func_82193_c(Entity par1Entity) //the amount of damage
{
return 4;
}
protected void fall(float par1)
{}
public int getMaxHealth() // Mob health
{
return 1000;
}
protected int getDropItemId()
{
return 0;
}
protected boolean canDespawn()
{
return false;
}
public boolean interact(EntityPlayer entityplayer)
{
if (riddenByEntity == null || riddenByEntity == entityplayer)
{
entityplayer.mountEntity(this);
return true;
}
else
{
return false;
}
}
protected boolean isMovementCeased()
{
return stationary;
}
public void moveEntity(double d, double d1, double d2)
{
if (riddenByEntity != null)
{
this.prevRotationYaw = this.rotationYaw = this.riddenByEntity.rotationYaw;
this.rotationPitch = this.riddenByEntity.rotationPitch * 0.5F;
this.setRotation(this.rotationYaw, this.rotationPitch);
this.rotationYawHead = this.renderYawOffset = this.rotationYaw;
stationary = true;
motionX += riddenByEntity.motionX * 10; // * 0.20000000000000001D;
motionZ += riddenByEntity.motionZ * 10; // * 0.20000000000000001D;
if (isCollidedHorizontally)
{
isJumping = true;
}
else
{
isJumping = false;
}
super.moveEntity(motionX, motionY, motionZ);
}
else
{
stationary = false;
super.moveEntity(d, d1, d2);
}
}
public void onUpdate()
{
super.onUpdate();
if (riddenByEntity != null) //check if there is a rider
{
//currentTarget = this;
this.randomYawVelocity = 0; //try not to let the horse control where to look.
this.rotationYaw = riddenByEntity.rotationYaw;
}
}
protected boolean isAIEnabled() //Allow your AI task to work?
{
return true;
}
}
P.S. I am using ModLoader

You need to add client-server-sync by using message-handling. I recommend using this tutorial: http://www.minecraftforge.net/forum/index.php/topic,20138.0.html