Android Intent重新开启活动

Question

I have an issue that I have not found a solution to on this site, but if this is a duplicate question, I apologize.

I am developing an application that serves as a terminal for registering when employees start/finish work, among numerous other things. The way it works is that with NFC switched-on, they scan their NFC cards and my app reads them and ultimately sends the appropriate information to the server.

However, if the app is already open (it's supposed to be open all the time, so this is an issue) and an NFC card is scanned, it reopens the app. Of course, this is done because I have set it that way in the manifest. But I can not find a way to have my app recieve the NFC scan intent if I do not add all of these lines in the manifest:

<intent-filter>
            <action android:name="android.nfc.action.TAG_DISCOVERED" />

            <category android:name="android.intent.category.DEFAULT" />
</intent-filter>

I have tried just writing without the but in that case it does not read the card, but instead the program chooser comes up on the phone, or if the phone does not have an appropriate app it simply says "NFC read error" .

Does anyone have a solution for this? This is the last step in my project, and I have had a lot of trouble with it, and would appreciate any help. It's probably something simple that I'm just not seeing, but I'd appreciate it either way.

Answer 1

Android activities have different launch modes. If you set single instance it will use already opened activity and doesn't create a new activity. You can read the new intent in override method onNewIntent()

protected void onNewIntent(Intent intent) {
  super.onNewIntent(intent);
  // read intent values here
}

For various activity elements

Answer 2

You can use broadcastReceiver, - first initiate the receiver to your activity

IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction("whateveryouwant");

    notificationBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
// here you can read the intent and customize the action;
            int usage = intent.getIntExtra("usage",1000); 


            }


        }
    };

• second register the broadcast

  registerReceiver(notificationBroadcastReceiver,intentFilter);

• At end unregister to the broadcast in the onDestroy method

  @Override protected void onDestroy() {

   if(notificationBroadcastReceiver != null){ unregisterReceiver(notificationBroadcastReceiver); notificationBroadcastReceiver = null; } super.onDestroy(); 

  }

after doing that instead of intenting activity you can sendBroadcast()

a little guide: https://developer.android.com/reference/android/content/BroadcastReceiver.html

hope it will be helpfull