如何在Android中将任何应用程序从后台移到前台（反之亦然）时发送通知

Question

Is there any way to know when any application comes from background to foreground and vice-verse ? I need some kind of mechanism for my own app to know that any application installed in device went from background to foreground (Main Screen) or went to background to foreground .

Answer 1

I do not think this is possible in Android for security reasons. If you want to see when applications are launched you must create a custom launcher.

Even so, I have been looking to do this for sometime and the closest I could get to similar functionality was to monitor running apps like so:

ActivityManager activityManager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
List<RunningAppProcessInfo> runningTasks = activityManager.getRunningAppProcesses();

So, if

runningTasks.get(0).importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND

then that task is in the foreground (if not then it is in background).

Answer 2

For checking if my app is in foreground, I was using this code:

  public static boolean isAppInForeground(Context context) {
  List<RunningAppProcessInfo> appProcesses = ((ActivityManager) context
    .getSystemService(Context.ACTIVITY_SERVICE)).getRunningAppProcesses();
  if (appProcesses == null) {
  return false;
  }
  final String packageName = context.getPackageName();
  for (RunningAppProcessInfo appProcess : appProcesses) {
    if (appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND
        && appProcess.processName.equals(packageName)) {
      return true;
    }
  }
  return false;
}