Exercise: Register a receiver for incoming phone calls

1. Target

In this exercise you define a broadcast receiver which listens to telephone state changes. If the phone receives a phone call, then our receiver will be notified and log a message.

2. Create project

Create a new project called de.vogella.android.receiver.phone . Also create an activity.

TIP:Remember that your receiver is only called if the user started it once. This requires an activity.

3. Implement receiver for the phone event

Create the MyPhoneReceiver class.

package de.vogella.android.receiver.phone;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.util.Log;

public class MyPhoneReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
                Bundle extras = intent.getExtras();
                if (extras != null) {
                        String state = extras.getString(TelephonyManager.EXTRA_STATE);
                        Log.w("MY_DEBUG_TAG", state);
                        if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
                                String phoneNumber = extras
                                                .getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
                                Log.w("MY_DEBUG_TAG", phoneNumber);
                        }
                }
        }
}

4. Request permission

Add the android.permission.READ_PHONE_STATE permission to your manifest file which allows you to listen to state changes in your receiver. Also Register your receiver in your manifest file. The resulting manifest should be similar to the following listing.

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

     <uses-sdk android:minSdkVersion="15" />

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

    <application
        android:icon="@drawable/icon"
        android:label="@string/app_name" >
           <activity
            android:name=".MainActivity"
            android:label="@string/title_activity_main" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver android:name="MyPhoneReceiver" >
            <intent-filter>
                <action android:name="android.intent.action.PHONE_STATE" >
                </action>
            </intent-filter>
        </receiver>
    </application>



</manifest>

5. Validate implementations

Install your application and simulate a phone call via the Android Device Monitor. Validate that your receiver is called and logs a message to the LogCat view.