下列程序的运行结果是______。 class A implements Runnable { int a iht i = 2 A(int x) { a = x } public void run() { while(i > 0) { System.out.println('线程' + a) i-- } } } public class Testl3 { public static void main(String[] args) { Thread a1 = new Thread(new A(1)) Thread a2 = new Thread(new A(2)) a1.start() a2.start() } }