//例5.1
public class tt
{
   public static void main(String args[ ]) 
   {
     subThread  t1= new subThread(" First");
     subThread  t2= new subThread(" Second");
     t1.start( );
     t2.start( );
   }
}

class subThread extends Thread
{  public subThread(String str)
   {   
        super(str);  
   }
     //注意：Thread類中的run( )方法具有public屬性，
     //覆蓋該方法時，前面必須帶上public。
   public void run( ) 
   {
      for(int i=0;i<10;i++)
      {
         System.out.println( i+ " " + getName( ));
         try  
           { sleep( (int)( Math.random( )*1000 ) );   } 	
	     catch(InterruptedException e)  {    }
      }
      System.out.println("Finished! " + getName( ));
   }
}