My simple backtracking code for N-Queens problem

NQueens.java

public class NQueens {

  private int[][] board;

  public static void main(String[] args) {

    NQueens queens = new NQueens();
    int size = 30;
    queens.init(size);

    if (queens.paintTheBoardWithQueens(0, size)) {
      queens.printArray();
    } else {
      System.out.println("No possible solution!");
    }
  }

  private void printArray() {

    for (int i = 0; i < board.length; i++) {
      for (int j = 0; j < board[i].length; j++) {
        System.out.print(board[i][j] + "\t");
      }
      System.out.println();
    }
    System.out.println();
  }

  private boolean paintTheBoardWithQueens(int level, int boardSize) {

    int tempX = 0;

    if (level == boardSize) {
      return true;
    }

    while (tempX < boardSize) {

      board[level][tempX] = 1;
      boolean wasPaintedCorrectly = checkIfQueenPlacedCorrectly(tempX, level);

      if (wasPaintedCorrectly && level < boardSize) {
        if (paintTheBoardWithQueens(level + 1, boardSize)) {
          return true;
        }
      }

      board[level][tempX] = 0;

      tempX++;
    }

    return false;
  }

  private void init(int n) {
    board = new int[n][n];
  }

  // Assuming y > tempY
  private boolean checkIfTheseTwoPointsAreSafeFromEachOther(int x, int y, int tempX, int tempY) {

    if (x == tempX) {
      return false;
    }

    return Math.abs(x - tempX) != Math.abs(y - tempY);
  }

  private boolean checkIfQueenPlacedCorrectly(int x, int y) {

    if (y == 0) {
      return true;
    }

    int tempX = 0;
    int tempY = y - 1;
    while (tempY >= 0) {
      while (board[tempY][tempX] != 1) {
        tempX++;
      }
      boolean check = checkIfTheseTwoPointsAreSafeFromEachOther(x, y, tempX, tempY);

      if (!check) {
        return false;
      }
      tempX = 0;
      tempY--;
    }

    return true;
  }
}