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：
代码语言：javascript复制<?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：
代码语言：javascript复制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。
