Android使用Handler实现倒计时功能

本文实例为大家分享了Android实现倒计时功能的具体代码，供大家参考，具体内容如下

1、实现效果

如下图所示：

2、代码实现

新建一个名为CountdownTime的项目，activity_main.xml代码如下：

<?xml version="1.0" encoding="utf-8"?>

MainActivity.class代码如下：

public class MainActivity extends AppCompatActivity {  /**   * 倒计时标记   */  public static final int COUNTDOWN_TIME_CODE = 99999;  /**   * 倒计时间隔   */  public static final int DELAY_MILLIS = 1000;  /**   * 倒计时最大值   */  public static final int MAX_COUNT = 10;  /**   * 文本控件   */  private TextView countdownTimeTextView;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //初始化文本控件    countdownTimeTextView = findViewById(R.id.countdownTimeTextView);    //创建一个handler    CountdownTimeHandler handler = new CountdownTimeHandler(this);    //新建一个message    Message message = Message.obtain();    message.what = COUNTDOWN_TIME_CODE;    message.arg1 = MAX_COUNT;    //第一次发送message    handler.sendMessageDelayed(message, DELAY_MILLIS);  }  public static class CountdownTimeHandler extends Handler {    /**     * 倒计时最小值     */    public static final int MIN_COUNT = 0;    //创建MainActivity弱引用    final WeakReference mWeakReference;    public CountdownTimeHandler(MainActivity activity) {      this.mWeakReference = new WeakReference<>(activity);    }    @Override    public void handleMessage(Message msg) {      super.handleMessage(msg);      //获取对MainActivity的弱引用      MainActivity activity = mWeakReference.get();      switch (msg.what) {        case COUNTDOWN_TIME_CODE:          int value = msg.arg1;          activity.countdownTimeTextView.setText(String.valueOf(value--));          //循环发送消息的控制          if (value >= MIN_COUNT) {            Message message = Message.obtain();            message.what = COUNTDOWN_TIME_CODE;            message.arg1 = value;            sendMessageDelayed(message, DELAY_MILLIS);          }          break;      }    }  }}

3、快捷键总结

Ctrl+Alt+F：改变变量的域
Ctrl+Alt+T：surrounded with快捷键
Ctrl+P：查看方法的参数

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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