Java 画一个5X5的方形矩阵

效果图如下：

思路：创建一个窗口，使其居中于屏幕中央，使用drawRect(x, y, width, height)画正方形。

 import java.awt.Graphics;
 import java.awt.Insets;
 import java.awt.Toolkit;
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;

 import javax.swing.JFrame;

 public class FiveXFive extends JFrame {

     public static void main(String[] args) {
         FiveXFive f = new FiveXFive();
         f.launchFrame();

     }

     public void launchFrame() {
         // The width & Height of the window
         final int formWidth = 500;
         final int formHeight = 500;
         // The width & Height of the screen
         int screenWidth = (int)Toolkit.getDefaultToolkit().getScreenSize().getWidth();
         int screenHeight = (int)Toolkit.getDefaultToolkit().getScreenSize().getHeight();

         // Set title, size, location & visible
         this.setTitle("Hello World! I'm coming!");
         // width + left + right, height + top + bottom
         this.setSize(formWidth+8+8, formHeight+31+8);
         // set window in the middle
         this.setLocation((screenWidth-formWidth)/2, (screenHeight-formHeight)/2);
         this.setVisible(true);

         Insets insets = this.getInsets();
         System.out.println("top: " + insets.top);
         System.out.println("bottom: " + insets.bottom);
         System.out.println("left: " + insets.left);
         System.out.println("right: " + insets.right);

         this.addWindowListener(new WindowAdapter() {
             public void windowClosing(WindowEvent e) {
                 System.exit(0);
             }
         });
     }

     public void paint(Graphics g) {
         g.drawLine(8, 31, 508, 531);
         g.drawLine(8, 531, 508, 31);
         for (int y = 31; y < (500+31); y += 100) {
             for (int x = 8; x < (500+8); x += 100) {
                 g.drawRect(x, y, 100, 100);
             }
         }
     }
 }