Android -条件编译

Question

我正在尝试实现一些在Android上运行的代码，从4.0版开始到8.0版。问题是库中的代码(jar)和最终用户可能希望使用旧的Android版本而不是8.0 (Oreo)来编译他的应用程序(用我的库)。因此，他将得到一个错误java.lang.Error: Unresolved compilation problems。

看看下面的代码：

NotificationManager notificationManager = (NotificationManager) context
            .getSystemService(Context.NOTIFICATION_SERVICE);

    //Build.VERSION_CODES.O is not defined in older versionof Android
    //So, I have to use a numeric value (26)
    //My Build.VERSION.SDK_INT = 21 (Lollipop)
    if (Build.VERSION.SDK_INT >= 26) {   
    //The next code is executed even if Build.VERSION.SDK_INT < 26 !!!          
        android.app.NotificationChannel channel = new android.app.NotificationChannel(
                NOTIFICATION_CHANNEL_ID,"ID_CHANNEL", NotificationManager.IMPORTANCE_LOW);

        channel.setShowBadge(false);
        channel.enableLights(true);
        channel.setLockscreenVisibility(android.app.Notification.VISIBILITY_PUBLIC);

        notificationManager.createNotificationChannel(channel);
    } 

因此，即使Build.VERSION.SDK_INT < 26在一个条件内的代码被执行并给出一个错误！如果用户使用较早版本的Android (如KITKAT或LOLLIPOP )编译他的项目，我如何省略这段代码？Android有条件编译吗？

任何帮助都将不胜感激！

Answer 1

这个问题已经用android.annotation.TargetApi解决了。因此，我重写了代码，如下所示：

@TargetApi(26)
private void createNotificationChannel(NotificationManager notificationManager){
    android.app.NotificationChannel channel = new android.app.NotificationChannel(
            NOTIFICATION_CHANNEL_ID, "ID_CHANNEL", NotificationManager.IMPORTANCE_LOW);

    channel.setShowBadge(false);
    channel.enableLights(true);
    channel.setLockscreenVisibility(android.app.Notification.VISIBILITY_PUBLIC);

    notificationManager.createNotificationChannel(channel);
}

public void init(Context context){
   NotificationManager notificationManager = (NotificationManager) context
        .getSystemService(Context.NOTIFICATION_SERVICE);

   //Build.VERSION_CODES.O is not defined in older version of Android
   //So, I have to use a numeric value (26)
   //My Build.VERSION.SDK_INT = 21 (Lollipop)
   if (Build.VERSION.SDK_INT >= 26) {   
      createNotificationChannel(notificationManager); 
   }
}

现在，它的工作没有任何错误。我希望它能帮到别人。