// app14_4, sleep() method的示范
class Ctest extends Thread  // 從Thread類擴展出子類Ctest
{
   private String id;
   public Ctest(String str){   // 構造函數，設置成員id
      id=str;
   }
   
   public void run(){    // 覆蓋Thread類里的run() method
      for(int i=0;i<4;i++){
         try{
            sleep((int)(1000*Math.random()));
         }
         catch(InterruptedException e){}
         System.out.println(id+" is running..");
      } 
   }
}
 
public class app14_4
{
   public static void main(String args[])
   {  
      Ctest dog=new Ctest("doggy");
      Ctest cat=new Ctest("kitty"); 
      dog.start(); 
      cat.start(); 
   }
}