下面的程序编译运行后输出的结果是（ 。Public class A implements Runnable { public static void main(String argv]) { A a = new A(); Thread t = new Thread(a); t.start(); } public void run() { while(true) { try{ Thread.currentThread().sleep(1000); }catch(InterruptedException e){ System.out.println(e.toString()); } System.out.println("looping while"); } }}