[Android] application이 background에 있는지 확인...

public static boolean isApplicationInBackground(Context context) 
{
    ActivityManager am = 
      (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

    List<RunningTaskInfo> tasks = am.getRunningTasks(1);

    if (!tasks.isEmpty()) 
    {
        ComponentName topActivity = tasks.get(0).topActivity;

        if (!topActivity.getPackageName().equals(context.getPackageName())) 
        {
            return true;
        }
    }

    return false;
}

 출처:
http://stackoverflow.com/questions/3236746/determining-if-app-is-running-in-background