class MyThread implements Runnable {
    public void run() {
        int i = 0;
        while(i < 6) {
            System.out.println(Thread.currentThread() + " a = " + i);
            i++;
            Thread.yield();
        }
    }
}
public class Demo1 {

    public static void main(String[] args) throws Exception {
        Thread t1 = new Thread(new MyThread(),"t1");
        Thread t2 = new Thread(new MyThread(),"t2");
        t1.start();
        t2.start();
    }

}

Thread[t1,5,main] a = 0
Thread[t2,5,main] a = 0
Thread[t1,5,main] a = 1
Thread[t2,5,main] a = 1
Thread[t1,5,main] a = 2
Thread[t2,5,main] a = 2
Thread[t2,5,main] a = 3
Thread[t2,5,main] a = 4
Thread[t1,5,main] a = 3
Thread[t1,5,main] a = 4
Thread[t2,5,main] a = 5
Thread[t1,5,main] a = 5