AndroidStudio项目制作倒计时模块的方法

<?xml version="1.0" encoding="utf-8"?><LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical"  tools:context="cn.edu.gdmec.android.counttime.MainActivity">  <!--填写倒计时时间-->  <EditText    android:id="@+id/input"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:ems="10"/>  <!--获取倒计时时间-->  <Button    android:id="@+id/get"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="获取倒计时时间"/>  <!--显示倒计时-->  <TextView    android:id="@+id/time"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    />  <!--开始计时-->  <Button    android:id="@+id/starttime"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="开始计时"/>  <!--停止计时-->  <Button    android:id="@+id/stoptime"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="停止计时"/></LinearLayout>

package cn.edu.gdmec.android.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 EditText inputet;  private Button get, startTime, stopTime;  private TextView time;  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.input);    get = findViewById(R.id.get);    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.get:        time.setText(inputet.getText().toString());        i = Integer.parseInt(inputet.getText().toString());        break;      case R.id.starttime:        startTime();        break;      case R.id.stoptime:        stopTime();        break;      default:        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() {      @Override      public void run() {        if (i > 0) {  //加入判断不能小于0          i--;          Message message = mHandler.obtainMessage();          message.arg1 = i;          mHandler.sendMessage(message);        }      }    };    timer.schedule(task, 1000);  }  public void stopTime(){    timer.cancel();  }}

//获取的按钮实现：time.setText(inputet.getText().toString());i = Integer.parseInt(inputet.getText().toString());//Handler的加入private Handler mHandler = new Handler() {    public void handleMessage(Message msg) {      time.setText(msg.arg1 + "");      startTime();    };  };//倒计时主要核心public void startTime() {    timer = new Timer();    task = new TimerTask() {      @Override      public void run() {        if (i > 0) {  //加入判断不能小于0          i--;          Message message = mHandler.obtainMessage();          message.arg1 = i;          mHandler.sendMessage(message);        }      }    };    timer.schedule(task, 1000);  }