Question

I’m trying to launch a specific activity when my phone scans an NFC Tag. This is what my manifest looks like:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.lgandroid.ddcnfc"
android:versionCode="1"
android:versionName="1.0" >

<uses-permission android:name="android.permission.NFC"/>

<uses-sdk
    android:minSdkVersion="14"
    android:targetSdkVersion="16" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.lgandroid.ddcnfc.BluePrintActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.nfc.action.NDEF_DISCOVERED"/>
            <data android:mimeType="application/com.lgandroid.ddcnfc"/>
            <category android:name="android.intent.category.DEFAULT"/>
        </intent-filter>
    </activity>
    <activity
        android:name="com.lgandroid.ddcnfc.LoginActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name="com.lgandroid.ddcnfc.MainActivity"
        android:label="@string/app_name" >
    </activity>
    <activity
        android:name="com.lgandroid.ddcnfc.PointDiagnosisActivity"
        android:label="@string/app_name" >
    </activity>
    <activity
        android:name="com.lgandroid.ddcnfc.PointControlActivity"
        android:label="@string/app_name" >
    </activity>
    <activity
        android:name="com.lgandroid.ddcnfc.SystemDiagnosisActivity"
        android:label="@string/app_name" >
    </activity>



    <activity android:name="com.lgandroid.ddcnfc.SettingsActivity" android:label="@string/app_name"></activity>
</application>

Whenever I scan my tag, my main activity launches but I’d like my BluePrintActivity to launch. I’m not sure why this is the case. Here is my code for writing to tag:

private boolean writeTag(Tag tag) {
        NdefRecord appRecord = NdefRecord.createApplicationRecord("com.lgandroid.ddcnfc");
        NdefMessage message = new NdefMessage(new NdefRecord[] { appRecord });

        try {
            // see if tag is already NDEF formatted
            Ndef ndef = Ndef.get(tag);
            if (ndef != null) {
                ndef.connect();

                if (!ndef.isWritable()) {
                    nfcTextView.setText("Read-only tag.");
                    return false;
                }

                // work out how much space we need for the data
                int size = message.toByteArray().length;
                if (ndef.getMaxSize() < size) {
                    nfcTextView.setText("Tag doesn't have enough free space.");
                    return false;
                }

                ndef.writeNdefMessage(message);
                nfcTextView.setText("Tag written successfully.");
                return true;
            } else {
                // attempt to format tag
                NdefFormatable format = NdefFormatable.get(tag);
                if (format != null) {
                    try {
                        format.connect();
                        format.format(message);
                        nfcTextView.setText("Tag written successfully!\nClose this app and scan tag.");
                        return true;
                    } catch (IOException e) {
                        nfcTextView.setText("Unable to format tag to NDEF.");
                        return false;
                    }
                } else {
                    nfcTextView.setText("Tag doesn't appear to support NDEF format.");
                    return false;
                }
            }
        } catch (Exception e) {
            nfcTextView.setText("Failed to write tag");
        }

        return false;
    }

Edit: The answer I accepted above hinted me towards the right direction but since I was writing to a tag, the code in the accepted answer is not exactly the correct solution. If you are writing to a tag, this is what you need to do:

 NdefRecord appRecord = new NdefRecord(
            NdefRecord.TNF_MIME_MEDIA ,
            "application/com.lgandroid.ddcnfc".getBytes(Charset.forName("US-ASCII")),
            new byte[0], new byte[0]);
    NdefMessage message = new NdefMessage(new NdefRecord[] { appRecord });

If you want to store a payload, just replace the last parameter “new byte[0]” to an appropriate data.

Answer 1

The reason your app starts is because you write an Android Application Record to the tag. This causes the application that has a matching package name to start up instead of the filtered activity.

Because you are filtering for a mime type you want to create a Mime Record with type ‘application/com.lgandroid.ddcnfc’ so instead of

NdefRecord appRecord = NdefRecord.createApplicationRecord("com.lgandroid.ddcnfc");

You should use:

NdefRecord appRecord = NdefRecord.createMimeRecord("application/com.lgandroid.ddcnfc", byteArray);