Question

我正在尝试实现一些适用于Android的代码，从4.0版开始到8.0版。问题是库（jar）和最终用户中的代码可能想要使用较旧的Android版本而不是8.0（Oreo）来编译他的应用程序（使用我的库）。结果，他将收到错误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条件中的代码被执行并出错！如果用户使用旧版Android（例如KITKAT或LOLLIPOP）编译项目，我该如何省略此代码？是否有针对Android的条件编译？

任何帮助将不胜感激！

Answer 1

使用android.annotation.TargetApi解决了问题。所以，我重写了我的代码，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); 
   }
}

现在它没有任何错误。我希望它可以帮助别人。

Android - 条件编译

1 个答案: