java - Pending intent always make new activity

Question

i trying to make app with nfc function. the problem is when nfc tag discovered, pending intent always make a new activity that already exist. i'm using tab host. how to make pendingintent without making a new activity. thanks a lot.

 public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);        

            mNfcAdapter = NfcAdapter.getDefaultAdapter(this);                              
            mNfcPendingIntent = PendingIntent.getActivity(this, 0,new Intent(this,
    getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    }

    protected void onResume() {    
            super.onResume();
            mResumed = true;               
            // Sticky notes received from Android
            if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {            
                NdefMessage[] messages = getNdefMessages(getIntent());
                byte[] payload = messages[0].getRecords()[0].getPayload();            
                try     { cekNfc(new String(payload)); }
                catch (SQLException e)          { e.printStackTrace(); } 
                catch (NoSuchAlgorithmException e)      {  e.printStackTrace(); }
                catch (UnsupportedEncodingException e)  { e.printStackTrace(); }

                setIntent(new Intent());
            }
            enableNdefExchangeMode();        
        }   
        private void enableNdefExchangeMode() { mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent, mNdefExchangeFilters, null); } 

    NdefMessage[] getNdefMessages(Intent intent) {  // Parse the intent             
            NdefMessage[] msgs = null;        
            String action = intent.getAction();
            //jika ada action
            if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action) || NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {                      
                Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
                if (rawMsgs != null) {
                    msgs = new NdefMessage[rawMsgs.length];
                    for (int i = 0; i < rawMsgs.length; i++) {  msgs[i] = (NdefMessage) rawMsgs[i]; }
                }
            } 
            return msgs;
        }


 public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);        

            mNfcAdapter = NfcAdapter.getDefaultAdapter(this);                              
            mNfcPendingIntent = PendingIntent.getActivity(this, 0,new Intent(this,
    getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    }

    protected void onResume() {    
            super.onResume();
            mResumed = true;               
            // Sticky notes received from Android
            if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {            
                NdefMessage[] messages = getNdefMessages(getIntent());
                byte[] payload = messages[0].getRecords()[0].getPayload();            
                try     { cekNfc(new String(payload)); }
                catch (SQLException e)          { e.printStackTrace(); } 
                catch (NoSuchAlgorithmException e)      {  e.printStackTrace(); }
                catch (UnsupportedEncodingException e)  { e.printStackTrace(); }

                setIntent(new Intent());
            }
            enableNdefExchangeMode();        
        }   
        private void enableNdefExchangeMode() { mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent, mNdefExchangeFilters, null); } 

    NdefMessage[] getNdefMessages(Intent intent) {  // Parse the intent             
            NdefMessage[] msgs = null;        
            String action = intent.getAction();
            //jika ada action
            if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action) || NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {                      
                Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
                if (rawMsgs != null) {
                    msgs = new NdefMessage[rawMsgs.length];
                    for (int i = 0; i < rawMsgs.length; i++) {  msgs[i] = (NdefMessage) rawMsgs[i]; }
                }
            } 
            return msgs;
        }

Answer 1

Put android:launchMode="singleTask" for your activity (or activities) in the manifest. That does the trick. Whenever an NFC intent is dispatched by the system, always a new Activity will be created. This is unique for NFC intents. So setting android:launchMode="singleTop" will not work, nor will setting flags in the PendingIntent.

Another solution is to use NfcAdapter.enableForegroundDispatch() in all your Activities. That way your app gets to handle all NFC intents itself directly (via onNewIntent()).