How to read multiple payload from nfc tags and store the payloads into an arraylist?

Hi Stackers I still new in coding and need some help. Now I have two NFC tags and both tags is storing with different Geo coordinates(longitude, latitude). Currently, I able to read the payload from the NFC tags. What I want is to store the payloads from both of the NFC tags into an arraylist. When I read the first tag it does stored the payload into arraylist, but when read second tag the payload will overwritten the previous payload.

Android Manifest:

<uses-permission android:name="android.permission.NFC" />
<uses-feature
android:name="android.hardware.nfc"
android:required="true" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".arraylist"></activity>
<activity
android:name=".MainActivity"
android:launchMode="singleInstance">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data
android:host="*"
android:scheme="geo" />
</intent-filter>
</activity>
</application>

MainActivity:

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (nfcAdapter == null) {
Toast.makeText(this, "nfc not supported", Toast.LENGTH_SHORT).show();
finish();
return;
}
if (!nfcAdapter.isEnabled()) {
startActivity(new Intent("android.settings.NFC_SETTINGS"));
Toast.makeText(this, "nfc not yet open", Toast.LENGTH_SHORT).show();
}
mPendingIntent = PendingIntent.getActivity(this,0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP),0 );
}
private void readIntent(Intent intent){
list = new ArrayList<>();
Parcelable[] parcelables = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
for(int i=0; i<parcelables.length; i ++){
NdefMessage message =(NdefMessage)parcelables[i];
NdefRecord[] records = message.getRecords();
for(int j=0; j<records.length; j++){
NdefRecord record = records[j];
byte[] original = record.getPayload();
byte[] value = Arrays.copyOfRange(original,0,original.length);
String payload = new String(value);
if(list != null){
list.add(payload);
System.out.println(list);
}
}
}
}
@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
readIntent(intent);
}
@Override
protected void onResume() {
super.onResume();
nfcAdapter.enableForegroundDispatch(this, mPendingIntent, null, null);
}
@Override
protected void onPause() {
super.onPause();
nfcAdapter.disableForegroundDispatch(this);
}

Here is my output:
I/System.out: [geo:1.523534,103.633690]

But my expectation output is:
[geo:1.523534, 103.633690, geo:1.5364496, 103.656321]

So how can achieve that second tag payload will not overwritten the previous payload?

The problem this time is that you are not creating a new instance of a Fragment like your were in your previous similar question, you are creating a new arraylist every time a card is read and thus de-referencing the first list object for it to be deleted by the garbage collection.

This is a classic variable initialisation issue.

readIntent is called every time a card is read.
So remove the first line of `readIntent where you create a new list.

e.g.

private void readIntent(Intent intent){
Parcelable[] parcelables = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
....

Then in your class definition initialise the arraylist once only.

e.g.

public class MainActivity extends AppCompatActivity {
private ArrayList<String> list = new ArrayList();