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File reader / adding patterns from file Game of Life

I am quite new to Java and I have this school assignment to write Conway's Game of Life. The task I am struggling with is reading a patterns from file. So far I got this code from tutorial from my school:
#FXML
private void readFromFile(){
FileChooser fileChooser = new FileChooser();
File openFile = fileChooser.showOpenDialog(null);
if(openFile == null){
return;
}
try (BufferedReader reader = Files.newBufferedReader(openFile.toPath())){
String line;
while ((line = reader.readLine()) != null){
addMessage(line);
}
}catch (IOException ex){
showIOErrorAlert(ex);
}
}
#FXML
private void showIOErrorAlert(IOException ex){
Alert alert = new Alert(Alert.AlertType.ERROR);
alert.setContentText("IOException, filen cannot be open: " + ex);
alert.show();
}
The code opens a window where I can choose a file from disk (I've downloaded all patterns in rle format , and I wish to open them rle format, because that is the assignments requirement). But when I choose a file nothing happens, not an error, nothing. What do I need to do that this work? Do I need to write a parser here? To read a rle format. I am using mvc model and java fxml this is my Cell class:
public class Cell extends Rectangle{
public static final int CELL_SIZE = 5;
private boolean alive;
public Cell(){
super(CELL_SIZE, CELL_SIZE);
setAlive(false);
}
public void setAlive(boolean bool){
alive = bool;
if (alive){
setFill(Color.WHITE);
} else {
setFill(Color.BLACK);
}
}
public boolean isAlive(){
return alive;
}
}
Board class:
public class Board {
public static final int COLUMNS = 90;
public static final int ROWS = 210;
private Cell[][] generation;
public Board(){
generation = new Cell[COLUMNS][ROWS];
for(int x = 0; x < COLUMNS; x++){
for(int y = 0; y < ROWS; y++){
generation[x][y] = new Cell();
}
}
}
public Cell[][] getBoard(){
return generation;
}
public void fill(){
Random rand = new Random();
for(int x = 0; x < COLUMNS; x++){
for(int y = 0; y < ROWS; y++){
generation[x][y].setAlive(rand.nextBoolean());
}
}
}
public void reset(){
for(int x = 0; x < COLUMNS; x++){
for(int y = 0; y < ROWS; y++){
generation[x][y].setAlive(false);
}
}
}
public int countNeighbors(int x, int y){
int neighbors = 0;
//iteration starts with -1 in order to 'wrap' the grid around
for (int a = -1; a < 2; a++){
for (int b = -1; b < 2; b++){
int nx = x + a;
int ny = y + b;
if (nx < 0){
nx = COLUMNS - 1;
}
if (ny < 0){
ny = ROWS - 1;
}
if (nx > COLUMNS - 1){
nx = 0;
}
if (ny > ROWS - 1){
ny = 0;
}
if(generation[nx][ny].isAlive()){
neighbors += 1;
}
}
}
if(generation[x][y].isAlive())
neighbors--;
return neighbors;
}
public void renew(){
Cell[][] nextGeneration = new Cell[COLUMNS][ROWS];
for(int x = 0; x < COLUMNS; x++){
for(int y = 0; y < ROWS; y++){
nextGeneration[x][y] = new Cell();
nextGeneration[x][y].setAlive(generation[x][y].isAlive());
}
}
int neighborsCount = 0;
for(int x = 0; x < COLUMNS; x++){
for(int y = 0; y < ROWS; y++){
neighborsCount = countNeighbors(x, y);
if(generation[x][y].isAlive()){
if(neighborsCount < 2 || neighborsCount > 3)
nextGeneration[x][y].setAlive(false);
}
else{
if(neighborsCount == 3)
nextGeneration[x][y].setAlive(true);
}
}
}
for(int x = 0; x < COLUMNS; x++){
for(int y = 0; y < ROWS; y++){
generation[x][y].setAlive(nextGeneration[x][y].isAlive());
}
}
}
How to write a method that reads a rle format file and adds a pattern to my board?

Implementing pacman game issue when moving it up and down

I am trying to build a simple pacman game, and I just got started.
Currently my constructor looks like this:
static String[][] board;
static int pacmanBornHeight;
static int pacmanBornWidth;
public PacmanKata(int height, int width) {
board = new String[height][width];
pacmanBornHeight = (int) Math.floor(height / 2);
pacmanBornWidth = (int) Math.floor(width / 2);
for (int i = 0; i < boardHeight; i++) {
for (int j = 0; j < boardWidth; j++) {
board[i][j] = "*";
}
}
board[pacmanBornHeight][pacmanBornWidth] = "V";
}
This constructor set up the board and the pacman will be located at the middle, I used "V" as the symbol.
I try to create two methods currenlty, move up and down.
Here is the setup:
I first called the tickUp method:
public void tickUp(int steps) {
int counter = 1;
int timer = 0;
for (int loop = 0; loop < steps; loop++) {
board[pacmanBornHeight - counter][pacmanBornWidth] = "V";
for (int innerTimer = 0; innerTimer < counter; innerTimer++) {
board[pacmanBornHeight - innerTimer][pacmanBornWidth] = " ";
}
counter++;
timer++;
}
for (int i = 0; i < boardHeight; i++) {
for (int j = 0; j < boardWidth; j++) {
System.out.print(board[i][j]);
}
System.out.println();
}
System.out.println("-------------------------");
} //end going UP
And I print out this to console(I initialized a 10 by 10 board):
Pacman moved up three steps, as expected, and eat three dots. I slightly modified and created a move down method:
public void tickDown(int steps) {
int counter = 1;
int timer = 0;
for (int loop = 0; loop < steps; loop++) {
board[pacmanBornHeight + counter][pacmanBornWidth] = "V";
for (int innerTimer = 0; innerTimer < counter; innerTimer++) {
board[pacmanBornHeight + innerTimer][pacmanBornWidth] = " ";
}
counter++;
timer++;
}
for (int i = 0; i < boardHeight; i++) {
for (int j = 0; j < boardWidth; j++) {
System.out.print(board[i][j]);
}
System.out.println();
}
System.out.println("-------------------------");
}//end tickDown
Now I called tickDown and asked it to move down 3 steps, but I got this result:
The trouble I am having is, I do not know how to locate the Pacman last location. The move down method simply created a new Pacman and moved down 3 steps, that is not what I want. How can I fix this?

Change your tickUp and tickDown methods to save the new position of your Pacman:
public void tickDown(int steps) {
int counter = 1;
int timer = 0;
for (int loop = 0; loop < steps; loop++) {
for (int innerTimer = 0; innerTimer < counter; innerTimer++) {
board[pacmanBornHeight + innerTimer][pacmanBornWidth] = " ";
}
pacmanBornHeight += counter;
//Allow for wraparounds:
if (pacmanBornHeight > board.length) {
pacmanBornHeight = 0;
}
board[pacmanBornHeight][pacmanBornWidth] = "V";
timer++;
}
for (int i = 0; i < boardHeight; i++) {
for (int j = 0; j < boardWidth; j++) {
System.out.print(board[i][j]);
}
System.out.println();
}
System.out.println("-------------------------");
}//end tickDown
I moved the loop to write spaces in the board to the beginning of the outer loop; that way you get the spaces based on the starting position of Pacman. Once you've written the spaces to the array, you update Pacman's position and write it in the array.
Edit:
Here's an example showing how you'd use a one-dimensional array as your board:
public class PacmanKata {
static String[] board;
static int pacmanPosition;
static int boardHeight;
static int boardWidth;
public static void main(String[] args) {
PacmanKata kata = new PacmanKata(10,10);
kata.tickUp(7);
kata.tickRight(9);
}
public PacmanKata(int height, int width) {
boardHeight = height;
boardWidth = width;
board = new String[height*width];
int offset = (width + 1) % 2;
pacmanPosition = (int) Math.floor((height + offset)*width/2);
for (int i = 0; i < board.length; i++) {
board[i] = "*";
}
board[pacmanPosition] = "V";
}
private void printBoard() {
for (int i = 0; i < board.length; i++) {
System.out.print(board[i]);
if ((i+1) % boardWidth == 0) {
System.out.println();
}
}
System.out.println("-------------------------");
}
public void tickUp(int steps) {
int counter = -1 * boardHeight;
for (int loop = 0; loop < steps; loop++) {
//Current position = ' '
board[pacmanPosition] = " ";
//Pacman's position changes:
pacmanPosition += counter;
//Allow for wraparounds:
if (pacmanPosition < 0) {
pacmanPosition += board.length;
}
//Update the board with Pacman's new position:
board[pacmanPosition] = "V";
}
printBoard();
}//end tickUp
public void tickRight(int steps) {
int counter = 1;
for (int loop = 0; loop < steps; loop++) {
//Current position = ' '
board[pacmanPosition] = " ";
//Pacman's position changes:
pacmanPosition += counter;
if (pacmanPosition % boardWidth == 0) {
pacmanPosition -= boardWidth;
}
//Update the board with Pacman's new position:
board[pacmanPosition] = "V";
}
printBoard();
}//end tickUp
}

Instead of having pacmanBornWidth and pacmanBornHeight fields, you should have a field with pacman current position (all fields shouldn't be static):
String[][] board;
java.awt.Point pacmenPos;
public PacmanKata(int height, int width) {
board = new String[height][width];
pacmanPos = new Point((int) width/2, (int) height/2);
for (int i = 0; i < boardHeight; i++) {
for (int j = 0; j < boardWidth; j++) {
board[i][j] = "*";
}
}
board[pacmanPos.x][pacmanPos.y] = "V";
}
Now replace all occurrences of pacmanBornWidth and pacmanBornHeight with pacmanPos.x and pacmanPos.y.
And in your tickUp and tickDown methods, just update pacman position:
public void tickUp(int steps) {
...
pacmanPos.translate(0, steps);
...
}
public void tickDown(int steps) {
...
pacmanPos.translate(0, -steps);
...
}
This will also work the same if you add tickLeft and tickRight methods:
public void tickLeft(int steps) {
...
pacmanPos.translate(-steps, 0);
...
}
public void tickRight(int steps) {
...
pacmanPos.translate(steps, 0);
...
}

How can i make this for loop shorter?

My head is not working anymore. I have to finish this a.s.a.p
How can i make this for loop shorter.
At the moment i have got 4 different for loop. I want to combine them and have only one.
Card[] cards = new Card[4*13];
void testCreateCards() {
int k = 0;
for (int suit = 0; suit <= 3; suit++) { // for suit
for (int value = 1; value <= 13; value++) { // from Ace to King
// build new card
cards[k++] = new Card(suit, value);
}
}
}
void testDrawClubs() {
int x = 0;
int y = 0;
for (int i = 0; i <= 12; i++) {
cards[i].displayCard(x, y);
x +=80;
}
}
void testDrawDiamonds() {
int x = 0;
int y = 80;
for (int i = 13; i <= 25; i++) {
cards[i].displayCard(x, y);
x +=80;
}
}
void testDrawHearts() {
int x = 0;
int y = 160;
for (int i = 26; i <= 38; i++) {
cards[i].displayCard(x, y);
x +=80;
}
}
void testDrawSpades() {
int x = 0;
int y = 240;
for (int i = 39; i <= 51; i++) {
cards[i].displayCard(x, y);
x +=80;
}
}

You can calculate x and y directly using modular arithmetic because i % 13 gives you the x-coordinate and i / 13 gives you the y-coordinate:
void testDrawCards() {
for (int i = 0; i < 52; i++) {
int x = i % 13;
int y = i / 13;
cards[i].displayCard(x * 80, y * 80);
}
}

nullpointerexception with multithreading

my program is to complete Conway's game of life using multithreading. i keep getting the error Exception in thread "main" java.lang.NullPointerException
at life.main(life.java:51)
the exception is thrown at different parts of its execution, never actually completing the first threading in its entirety. any help would be appreciated.
import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;
public class life {
final static int rowBound = 9;
final static int colBound = 9;
static int numThreads;
static boolean matrix[][];
static boolean prevMatrix[][];
static boolean newMatrix[][];
static boolean stable;
public static void main(String[] args) {
matrix = new boolean[rowBound+1][colBound+1];
prevMatrix = new boolean[rowBound+1][colBound+1];
newMatrix = new boolean[rowBound+1][colBound+1];
stable = false;
Scanner in = new Scanner (System.in);
numThreads = 8;
matrix = fillMatrix(matrix);
Random r = new Random();
matrix = initializeMatrix(matrix, r);
printMatrix(matrix);
Thread[] threads = new Thread[numThreads];
while (!stable){
for (int i = 1; i < numThreads; ++i) {
Runnable prod = new update(i, newMatrix);
threads[i] = new Thread(prod);
threads[i].start();
}
for (Thread t : threads) {
try {
t.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
stable = compare(prevMatrix, newMatrix);
printMatrix(newMatrix);
if (!stable){
prevMatrix = give(prevMatrix, matrix);
matrix = give(matrix, newMatrix);
}
}
}
// fill matrix with false
public static boolean[][] fillMatrix(boolean[][] mat) {
for (int x = 0; x < rowBound; x++) {
for (int y = 0; y < colBound; y++) {
mat[x][y] = false;
}
}
return mat;
}
// initializes the matrix
public static boolean[][] initializeMatrix(boolean[][] mat, Random r) {
for (int x = 1; x < rowBound; x++) {
for (int y = 1; y < colBound; y++)
mat[x][y] = r.nextBoolean();
}
return mat;
}
// print matrix
public static void printMatrix(boolean[][] matrix) {
System.out.println("Dead cell --> '-' Live cell --> '+'");
for (int x = 0; x <= rowBound; x++) {
for (int y = 0; y <= colBound; y++) {
if (!matrix[x][y])
System.out.print(" -");
else
System.out.print(" #");
}
System.out.println();
}
}
public static boolean compare(boolean[][] prevM, boolean[][] newM) {
for (int a = 1; a < rowBound-1; a++){
for (int b = 1; b < colBound-1; b++){
if (prevM[a][b] != newM[a][b])
return false;
}
}
return true;
}
static class update implements Runnable {
int counter;
int numRows;
int firstRow;
int lastRow;
int thread;
public update(int i, boolean[][] newMatrix) {
thread = i;
}
#Override
public void run() {
numRows = 1;
firstRow = thread * numRows;
lastRow = numRows + firstRow;
counter = 0;
for (int a = firstRow; a < lastRow; a++) {
for (int b = 1; b < colBound; b++) {
for (int c = a - 1; c <= a + 1; c++) {
for (int d = b - 1; d <= b + 1; d++) {
if (matrix[c][d] == true)
counter++;
}
}
if (matrix[a][b]) {
counter--;
if (counter < 4) {
if (counter > 1)
newMatrix[a][b] = true;
else
newMatrix[a][b] = false;
} else
newMatrix[a][b] = false;
} else {
if (counter == 3)
newMatrix[a][b] = true;
else
newMatrix[a][b] = false;
}
}
}
}
}
// gives the values from the newMatrix and puts them into matrix
public static boolean[][] give(boolean[][] matrix, boolean[][] newMatrix) {
for (int x = 0; x < rowBound; x++) {
for (int y = 0; y < colBound; y++) {
matrix[x][y] = newMatrix[x][y];
}
}
return matrix;
}
}

You are getting an NPE as you never assign a Thread at index position 0:
for (int i = 1; i < numThreads; ++i) {
so the exception is thrown when attempting to access it here:
for (Thread t : threads) {
...
t.join(); // NPE

How to perform despeckle operation without using JAI,ImageJ,jhlab libraries?

I am making an app in Netbeans using Java Swing. I want to achieve some image processing functionality (like in ImageJ) in my app without using the ImageJ, JAI and jhlab libraries.
For example: ImageJ>>Process>>Noise>>Despeckle.
So, how can I do this?

This might helpful
private void removeNoise() {
int iterator;
for (int row = 0; row < x1; row++) {
for (int column = 0; column < y1; column++) {
if (row == 0 || row == x1 - 1 || column == 0
|| column == y1 - 1) {
result[row][column] = result[row][column];
continue;
} else {
iterator = 0;
for (int r = row - 1; r < row + 2; r++) {
for (int c = column - 1; c < column + 2; c++) {
surround[iterator] = result[r][c];
iterator++;
}
}
result[row][column] =
sortMedian(surround, 9); //calls the sorting method
}
}
}
setPixel();
}
private int sortMedian(int[] surround1, int x) {
int i, j, t = 0;
for (i = 0; i < 9; i++) {
for (j = 1; j < (9 - i); j++) {
if (surround1[j - 1] > surround1[j]) {
t = surround1[j - 1];
surround1[j - 1] = surround1[j];
surround1[j] = t;
}
}
}
return surround1[4];
}
private void setPixel() {
int[] pixel = new int[1];
for (int x = 0; x < bi.getWidth(); x++) {
for (int y = 0; y < bi.getHeight(); y++) {
pixel[0] = (int) result[x][y];
rnImage.getRaster().setPixel(x, y, pixel);
}
}
}