通过实现Runnable接口创建线程,请在画线处加入正确的代码完成此程序【 】。 public class ThreadTest { public static void main(String args[ ]) { Thread t1=new Thread(new Hello()); Thread t2=new Thread(new Hello()); ______; t2.start(); } } class Hello implements Runnable { int i; public void run() { while(true) { System.out.println('Hello'+i++); if(i==5) break; } } }