Android NFC example, to read tag info of RFID key and card

A simple Android example to read info of RFID tag (key and card in this demo) using NFC.

Edit src/main/AndroidManifest.xml to add <intent-filter> with action of "android.nfc.action.TAG_DISCOVERED" and category of "android.intent.category.DEFAULT", such that the app will be started when RFID tag place near NFC; if no other apps registered.

And add <uses-permission> of "android.permission.NFC", and <uses-feature> of "android.hardware.nfc"

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.blogspot.android_er.androidnfctagdiscovered" >

    <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:supportsRtl="true"
        android:theme="@style/AppTheme" >
        <activity android:name=".MainActivity" >
            <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.TAG_DISCOVERED"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

In MainActivity.java:

In onCreate():
Create NfcAdapter object by calling NfcAdapter.getDefaultAdapter(this). And check if NFC supported and enabled.

Override onResume():
Check if intent is ACTION_TAG_DISCOVERED. if yes, we can obtain a Tag object from the intent, by calling intent.getParcelableExtra(NfcAdapter.EXTRA_TAG).

package com.blogspot.android_er.androidnfctagdiscovered;

import android.content.Intent;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private NfcAdapter nfcAdapter;
    TextView textViewInfo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textViewInfo = (TextView)findViewById(R.id.info);

        nfcAdapter = NfcAdapter.getDefaultAdapter(this);
        if(nfcAdapter == null){
            Toast.makeText(this,
                    "NFC NOT supported on this devices!",
                    Toast.LENGTH_LONG).show();
            finish();
        }else if(!nfcAdapter.isEnabled()){
            Toast.makeText(this,
                    "NFC NOT Enabled!",
                    Toast.LENGTH_LONG).show();
            finish();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();

        Intent intent = getIntent();
        String action = intent.getAction();

        if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action)) {
            Toast.makeText(this,
                    "onResume() - ACTION_TAG_DISCOVERED",
                    Toast.LENGTH_SHORT).show();

            Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
            if(tag == null){
                textViewInfo.setText("tag == null");
            }else{
                String tagInfo = tag.toString() + "\n";

                tagInfo += "\nTag Id: \n";
                byte[] tagId = tag.getId();
                tagInfo += "length = " + tagId.length +"\n";
                for(int i=0; i<tagId.length; i++){
                    tagInfo += Integer.toHexString(tagId[i] & 0xFF) + " ";
                }
                tagInfo += "\n";

                String[] techList = tag.getTechList();
                tagInfo += "\nTech List\n";
                tagInfo += "length = " + techList.length +"\n";
                for(int i=0; i<techList.length; i++){
                    tagInfo += techList[i] + "\n ";
                }

                textViewInfo.setText(tagInfo);
            }
        }else{
            Toast.makeText(this,
                    "onResume() : " + action,
                    Toast.LENGTH_SHORT).show();
        }

    }
}

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold"/>

    <TextView
        android:id="@+id/info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>