Android Thread.sleep行为

Question

我正在考虑在android中制作一个计时器 这是主要代码。

    TextView tv1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_scrolling);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    tv1 = (TextView)findViewById(R.id.host_place);
    final incrementTimer k = new incrementTimer();
    tv1.setText("00:00");

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
            int i=0;
            while(i!=2){
            try{
                String alteredTime = k.startTimer(tv1.getText().toString());
                tv1.setText(alteredTime);
                Thread.sleep(1000);}
            catch(InterruptedException ie)
            {
                tv1.setText(ie+"");
            }i++;}
        }
    });
}

和incrementTimer（）代码是：

public class incrementTimer {
    public String startTimer(String currTime) throws InterruptedException {
        int zPos = Integer.parseInt(""+currTime.charAt(0));
        int fPos = Integer.parseInt(""+currTime.charAt(1));
        int sPos = Integer.parseInt(""+currTime.charAt(3));
        int tPos = Integer.parseInt(""+currTime.charAt(4));
        int hh = zPos*10 + fPos;
        int mi = sPos*10 + tPos;
        //----Incrementing minutes
        if(mi==60){
            hh+=1;
            mi=0;
        }
        else
            mi+=1;
        if(hh==24) {
            hh = 0;
        }
        if(mi<10 && hh<10){
            return "0"+hh+":0"+mi+"";
        }
        if(hh<10){
            return "0"+hh+":"+mi+"";
        }
        if(mi<10){
            return ""+hh+":0"+mi+"";
        }
        return ""+hh+":"+mi+"";
    }
}

直接显示00:02而不显示00:01。

点击后
请帮忙我就这个。我是android编程的新手。它在java中运行良好。