Java n皇后问题 图形界面实现 经典范例

package taskQueen;

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.Container;

import java.awt.FlowLayout;

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.ImageIcon;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JOptionPane;

import javax.swing.JPanel;

import javax.swing.JTextField;

import javax.swing.border.LineBorder;

public class queen extends JFrame implements ActionListener { /**

* @ n皇后问题---西北农林科技大学信息工程学院* 作者：计算机科学与技术103班博灵

* 完成时间：2012年10月26日

* 最大演示皇后数：11

*/

private static final long serialVersionUID = 1L;

static int n;

static int [] a = new int[25];

static int[][][] b = new int[10000][20][20];

static int count = 0;

static int q = 1;

private JButton next;

private JButton exit;

private JButton prev;

public JPanel panel2;

private JLabel label[][];

private JTextField text;

public queen() {

Container container = this.getContentPane();

container.setLayout(new BorderLayout());

this.setBounds(100, 100, 500, 500);

//this should be put forward or the graphic can't be work well

JPanel panel1 = new JPanel();

panel1.setLayout(new FlowLayout());

next = new JButton();

next.setText("Next");

exit = new JButton("Exit");

prev = new JButton("Prev");

panel1.add(next);

panel1.add(exit);

panel1.add(prev);

next.addActionListener(this);

exit.addActionListener(this);

prev.addActionListener(this);

container.add(panel1, BorderLayout.NORTH);

panel2 = new JPanel();

GridLayout grid = new GridLayout(n, 0);

panel2.setLayout(grid);

label = new JLabel[20][20];

container.add(panel2, BorderLayout.CENTER);

text = new JTextField(10);

text.setText("请点击Next按钮开始演示N皇后问题");

text.setEditable(false);

text.addActionListener(this);

container.add(text, "South");

this.setVisible(true);

this.setTitle("N皇后问题图形演示（回溯法）————计算机103班博灵");

this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);

}

public static boolean check(int n) {

for (int i = 1; i < n; i++) {

if (a[i] == a[n] || (Math.abs(i - n) == Math.abs(a[i] - a[n]))) return false;

}

return true;

}

public void output(int n) {

++count;

//output the axis value and used for debug

System.out.println("The " + count + "'s answer is :");

for (int i = 1; i <= n; i++)

System.out.print("(" + i + "," + a[i] + ")" + " ");

System.out.println();

for (int i = 1; i <= n; i++) {

for (int j = 1; j <= n; j++) {

if (a[i] == j) {

b[count][i][j] = 1;

} else

b[count][i][j] = 0;

}

}

}

public void Backtrack(int t, int n) {

if (t > n) {

output(n);

} else

for (int i = 1; i <= n; i++) {

a[t] = i;

if (check(t))

Backtrack(t + 1, n);

}

}

public static void main(String[] args) {

// TODO Auto-generated method stub

String input = JOptionPane.showInputDialog("请输入皇后的个数: (N<=11)");

n = Integer.valueOf(input);

for(int i=0; i<25; i++)

a[i] =0;

queen qe = new queen();

qe.Backtrack(1, n);

qe.draw();

}

public void draw(){

panel2.removeAll();

for (int i = 1; i <= n; i++) {

for (int j = 1; j <= n; j++) {

label[i][j] = new JLabel();

if (b[q][i][j] == 1) {

label[i][j].setOpaque(true);//make the foreground effective;

label[i][j].setBackground(Color.red);

label[i][j].setBorder(new LineBorder(Color.black));

label[i][j].setIcon(new ImageIcon("c.jpg"));

} else {

label[i][j].setOpaque(true);

label[i][j].setBackground(Color.white);

label[i][j].setBorder(new LineBorder(Color.black));

}

panel2.add(label[i][j]);

}

}

panel2.updateUI();

}

public void actionPerformed(ActionEvent e) {

// TODO Auto-generated method stub

if (e.getSource() == next) {

++q;

System.out.println("q="+q);

if (q > count) {

JOptionPane.showMessageDialog(null, "Demonstrate is Finished");

}

else

{

text.setText(n+"皇后有"+count+"种解,这是第"+q+"种解");

draw();

}

}

if(e.getSource()==prev){

--q;

System.out.println("q="+q);

if (q <=0) {

JOptionPane.showMessageDialog(null, "Demonstrate is Finished");

}

else

{

text.setText(n+"皇后有"+count+"种解,这是第"+q+"种

解");

draw();

}

}

if (e.getSource() == exit) {

System.exit(0);

}

}

}