Android 9 Development Cookbook - Third Edition

How to do it...

We only need a single TextView on the layout to display the event information. Open the activity_main.xml file and follow these steps:

1. Add or modify the TextView as follows:

<TextView    android:id="@+id/textView"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    app:layout_constraintLeft_toLeftOf="parent"    app:layout_constraintTop_toTopOf="parent" />

2. Add the following permission to the Android Manifest:

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

3. Open MainActivity.java and add the following PhoneStateListener class to the MainActivity class:

PhoneStateListener mPhoneStateListener = new PhoneStateListener() {    @Override    public void onCallStateChanged(int state, String number) ...