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 >
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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 ;
}
}
}
}
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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