Grid.java

import java.util.*;

/**
 * {@code Grid} instances represent the grid in <i>The Game of Life</i>.
 */
public class Grid implements Iterable<Cell> {

    private final int numberOfRows;
    private final int numberOfColumns;
    private final Cell[][] cells;

    /**
     * Creates a new {@code Grid} instance given the number of rows and columns.
     *
     * @param numberOfRows    the number of rows
     * @param numberOfColumns the number of columns
     * @throws IllegalArgumentException if {@code numberOfRows} or {@code numberOfColumns} are
     *                                  less than or equal to 0
     */
    public Grid(int numberOfRows, int numberOfColumns) {
        this.numberOfRows = numberOfRows;
        this.numberOfColumns = numberOfColumns;
        this.cells = createCells();
    }

    @Override
    public Iterator<Cell> iterator() {
        return new GridIterator(this);
    }

    private Cell[][] createCells() {
        Cell[][] cells = new Cell[getNumberOfRows()][getNumberOfColumns()];
        for (int rowIndex = 0; rowIndex < getNumberOfRows(); rowIndex++) {
            for (int columnIndex = 0; columnIndex < getNumberOfColumns(); columnIndex++) {
                cells[rowIndex][columnIndex] = new Cell();
            }
        }
        return cells;
    }

    /**
     * Returns the {@link Cell} at the given index.
     *
     * <p>Note that the index is wrapped around so that a {@link Cell} is always returned.
     *
     * @param rowIndex    the row index of the {@link Cell}
     * @param columnIndex the column index of the {@link Cell}
     * @return the {@link Cell} at the given row and column index
     */
    public Cell getCell(int rowIndex, int columnIndex) {
        return cells[getWrappedRowIndex(rowIndex)][getWrappedColumnIndex(columnIndex)];
    }

    private int getWrappedRowIndex(int rowIndex) {
        return (rowIndex + getNumberOfRows()) % getNumberOfRows();
    }

    private int getWrappedColumnIndex(int columnIndex) {
        return (columnIndex + getNumberOfColumns()) % getNumberOfColumns();
    }

    /**
     * Returns the number of rows in this {@code Grid}.
     *
     * @return the number of rows in this {@code Grid}
     */
    public int getNumberOfRows() {
        return numberOfRows;
    }

    /**
     * Returns the number of columns in this {@code Grid}.
     *
     * @return the number of columns in this {@code Grid}
     */
    public int getNumberOfColumns() {
        return numberOfColumns;
    }

    /**
     * Transitions all {@link Cell}s in this {@code Grid} to the next generation.
     *
     * <p>The following rules are applied:
     * <ul>
     * <li>Any live {@link Cell} with fewer than two live neighbours dies, i.e. underpopulation.</li>
     * <li>Any live {@link Cell} with two or three live neighbours lives on to the next
     *      * generation.</li>
     * <li>Any live {@link Cell} with more than three live neighbours dies, i.e. overpopulation.</li>
     * <li>Any dead {@link Cell} with exactly three live neighbours becomes a live cell, i.e.
     * reproduction.</li>
     * </ul>
     */
    void nextGeneration() {
        goToNextState(calculateNextStates());
    }
    public List<Cell> getNeighbours(int rowIndex, int colummIndex) {
        List<Cell> listofNeighbours= new ArrayList<Cell>(0);
        listofNeighbours.add(getCell(rowIndex+1,colummIndex-1));
        listofNeighbours.add(getCell(rowIndex+1,colummIndex));
        listofNeighbours.add(getCell(rowIndex+1,colummIndex+1));
        listofNeighbours.add(getCell(rowIndex,colummIndex+1));
        listofNeighbours.add(getCell(rowIndex-1,colummIndex+1));
        listofNeighbours.add(getCell(rowIndex-1,colummIndex));
        listofNeighbours.add(getCell(rowIndex-1,colummIndex-1));
        listofNeighbours.add(getCell(rowIndex,colummIndex-1));
        return listofNeighbours;

    }
    private int countAliveNeighbours(int rowIndex, int columnIndex) {
        int AliveNeighbours=0;
        for (Cell Neighbour  :  getNeighbours(rowIndex,columnIndex)){
            if (Neighbour.isAlive())
                AliveNeighbours++;
        }
        return AliveNeighbours;
    }
    private boolean calculateNextState(int rowIndex, int columnIndex){
        if (countAliveNeighbours(rowIndex,columnIndex)==3 && !getCell(rowIndex,columnIndex).isAlive())
            return true;

        if (getCell(rowIndex,columnIndex).isAlive() && (countAliveNeighbours(rowIndex,columnIndex)==2 || countAliveNeighbours(rowIndex,columnIndex) == 3))
            return true;
        else
            return false;
    }

    private boolean[][] calculateNextStates() {
        boolean[][] tableau=new boolean[numberOfRows][numberOfColumns];
        for (int row=0;row<numberOfRows;row++){
            for (int column=0;column<numberOfColumns;column++){
                tableau[row][column]=calculateNextState(row,column);
            }
        }
        return tableau;
    }



    private void goToNextState(boolean[][] nextState) {
        for (int i = 0; i <numberOfRows ; i++) {
            for (int j = 0; j <numberOfColumns ; j++) {
                if (nextState[i][j])
                    getCell(i,j).setAlive();
                else
                getCell(i,j).setDead();
            }
        }
    }

    /**
     * Sets all {@link Cell}s in this {@code Grid} as dead.
     */
    void clear() {
        for (int i = 0; i <numberOfRows ; i++) {
            for (int j = 0; j <numberOfColumns ; j++) {
                getCell(i,j).setDead();
            }
        }
    }

    /**
     * Goes through each {@link Cell} in this {@code Grid} and randomly sets it as alive or dead.
     *
     * @param random {@link Random} instance used to decide if each {@link Cell} is alive or dead
     * @throws NullPointerException if {@code random} is {@code null}
     */
 
    void randomGeneration(Random random) {
        for (int i = 0; i <numberOfRows ; i++) {
            for (int j = 0; j <numberOfColumns ; j++) {
                if (random.nextBoolean())
                    getCell(i,j).setAlive();
                else
                getCell(i,j).setDead();

            }

        }
    }

}