MainActivity.java

package andersonleite.com.pretest;

import android.app.PendingIntent;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NfcAdapter;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;


public class MainActivity extends ActionBarActivity {

    private static final String TAG = "NFC";
    private NfcAdapter nfcAdapter;
    private PendingIntent nfcPendingIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialize NFC
        nfcAdapter = NfcAdapter.getDefaultAdapter(this);
        nfcPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, this.getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.d(TAG, "enableForegroundMode");

        // foreground mode gives the current active application priority for reading scanned tags
        IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED); // filter for tags
        IntentFilter[] writeTagFilters = new IntentFilter[] {tagDetected};
        nfcAdapter.enableForegroundDispatch(this, nfcPendingIntent, writeTagFilters, null);
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

        Log.d(TAG, "onNewIntent");

        // check for NFC related actions
        if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())) {
            ImageView lata = (ImageView) findViewById(R.id.lata);

            if(lata.getVisibility()== View.VISIBLE)
                lata.setVisibility(View.INVISIBLE);
            else{
                lata.setVisibility(View.VISIBLE);
            }

        }

    }
}