public class Tortoise implements Runnable  {
    private int totalStep;
    private int step;

    public Tortoise(int totalStep) {
        this.totalStep = totalStep;
    }

    @Override
    public void run() {
        while (step < totalStep) {
            step++;
            System.out.printf("乌龟跑了 %d 步 %n", step);
        }
    }
}