Handle 倒计时

public class HomeActivity extends AppCompatActivity {

    private TextView tv_text;
    private Handler handler = new Handler();
    int i=3;
    private Runnable runnable=new Runnable() {
        @Override
        public void run() {
            if (i>0){
                i--;
                tv_text.setText("距离倒计时还有"+i+"秒");
            }else if (i==0){
                Intent intent=new Intent(HomeActivity.this,MainActivity.class);
                startActivity(intent);
                finish();
                i=-1;
            }
            handler.postDelayed(runnable,1000);
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);
        initView();
    }

    private void initView() {
        tv_text = (TextView) findViewById(R.id.tv_text);
        tv_text .setText("距离倒计时还有3秒");
        handler.postDelayed(runnable,1000);
    }
}