简单倒计时的实现

一个编辑框,一个按钮用来显示输入的时间,两个按钮分别用来开始计时,和停止计时

package com.example.admin.counttime;

import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    private Button getTime,startTime,stopTime;

    private TextView time;

    private EditText inputet;

    private int i = 0;

    private Timer timer = null;

    private TimerTask task = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView(){
        inputet = findViewById(R.id.inputtime);
        getTime = findViewById(R.id.gettime);
        startTime = findViewById(R.id.starttime);
        stopTime = findViewById(R.id.stoptime);
        time = findViewById(R.id.time);
        getTime.setOnClickListener(this);
        startTime.setOnClickListener(this);
        stopTime.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.gettime:
                time.setText(inputet.getText().toString());
                i = Integer.parseInt(inputet.getText().toString());
                break;
            case R.id.starttime:
                startTime();
                break;
            case R.id.stoptime:
                stopTime();
                break;

        }
    }

    private Handler mHandler = new Handler(){
        public void handleMessage(Message msg){
            time.setText(msg.arg1+"");
            startTime();
        }
    };

    public void startTime(){
        timer = new Timer();
        task = new TimerTask(){
            public void run(){
                i--;
                Message message = mHandler.obtainMessage();
                message.arg1 = i;
                mHandler.sendMessage(message);
            }
        };
        timer.schedule(task,1000);
    }

    public void stopTime(){
        timer.cancel();
    }
}