rough

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class NQueen extends JFrame{

    public NQueen() {
        initUI();
    }

    public void initUI() {

        JPanel jp = new JPanel();
        getContentPane().add(jp);

        jp.setLayout(null);

                    এইখানে show করাতে হবে nQueen(1);

        setTitle("NQueen Problem");
        setSize(800, 650);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    final int N = 4;

    Integer[] x = new Integer[N + 1];

    Boolean place(int queen, int row) {
        for (int prev = 1; prev < queen; prev++) {
            if (x[prev] == row || Math.abs(prev - queen) == Math.abs(x[prev] - row)) {
                return false;
            }
        }
        return true;
    }

    void nQueen(int queen) {
        for (int row = 1; row <= N; row++) {
            if ( place(queen, row) ) {
                x[queen] = row;
                if (queen == N) {
                    for (int i = 1; i <= N; i++) {
                        for (int j = 1; j <= N; j++) {
                            if (j != x[i]) {
                                System.out.print(0 + " ");
                            } else {
                                System.out.print(x[i] + " ");
                            }
                        }
                        System.out.println();
                    }
                    System.out.println();
                } else {
                    nQueen(queen + 1);
                }
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                NQueen instance = new NQueen();
                instance.setVisible(true);
//              instance.nQueen(1);
            }
        });
    }

}