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：
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<?xml version="1.0" encoding="utf-8"?><RelativeLayout 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" tools:context=".MainActivity"> <TextView android:id="@+id/countdownTimeTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:text="@string/maxTime" android:textSize="60sp" /></RelativeLayout> |
MainActivity.class代码如下：
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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<MainActivity> 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服务器之家。
原文链接：https://blog.csdn.net/qingjianduoyun/article/details/80630940
