import java.awt.*; import java.util.*;  import javax.swing.*; public class SleepMethodTest extends JFrame {   /**    *    */   private static final long serialVersionUID = 1L;   private Thread t;   // 定義顏色數(shù)組   private static Color[] color = { Color.BLACK, Color.BLUE, Color.CYAN,       Color.GREEN, Color.ORANGE, Color.YELLOW, Color.RED,       Color.PINK, Color.LIGHT_GRAY };   private static final Random rand = new Random();// 創(chuàng)建隨機(jī)對(duì)象      private static Color getC() {// 獲取隨機(jī)顏色值的方法     return color[rand.nextInt(color.length)];   }      public SleepMethodTest() {     t = new Thread(new Runnable() {// 創(chuàng)建匿名線程對(duì)象       int x = 30;// 定義初始坐標(biāo)       int y = 50;              public void run() {// 覆蓋線程接口方法         while (true) {// 無限循環(huán)           try {             Thread.sleep(100);// 線程休眠0.1秒           } catch (InterruptedException e) {             e.printStackTrace();           }           // 獲取組件繪圖上下文對(duì)象           Graphics graphics = getGraphics();           graphics.setColor(getC());// 設(shè)置繪圖顏色           // 繪制直線并遞增垂直坐標(biāo)           graphics.drawLine(x, y, 100, y++);           if (y >= 80) {             y = 50;           }         }       }     });     t.start();// 啟動(dòng)線程   }      public static void main(String[] args) {     init(new SleepMethodTest(), 100, 100);   }   // 初始化程序界面的方法   public static void init(JFrame frame, int width, int height) {     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);     frame.setSize(width, height);     frame.setVisible(true);   } }