Android READ PHONE STATE?

Question

I'm trying to make app to READ PHONE STATE and when the phone state is changed to display Toast with the current state. But when I start it, the app stops unexpectedly.

my class :

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.widget.TextView;

public class TelephonyDemo extends Activity {
    TextView textOut;
    TelephonyManager telephonyManager;
    PhoneStateListener listener;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Get the UI
        textOut = (TextView) findViewById(R.id.textOut);

        // Get the telephony manager
        telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);

        // Create a new PhoneStateListener
        listener = new PhoneStateListener() {
            @Override
            public void onCallStateChanged(int state, String incomingNumber) {
                String stateString = "N/A";
                switch (state) {
                case TelephonyManager.CALL_STATE_IDLE:
                    stateString = "Idle";
                    break;
                case TelephonyManager.CALL_STATE_OFFHOOK:
                    stateString = "Off Hook";
                    break;
                case TelephonyManager.CALL_STATE_RINGING:
                    stateString = "Ringing";
                    break;
                }
                textOut.append(String.format("\nonCallStateChanged: %s",
                        stateString));
            }
        };

        // Register the listener with the telephony manager
        telephonyManager.listen(listener, PhoneStateListener.LISTEN_CALL_STATE);
    }
}

my manifest is :

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

    <application
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.Light" >
        <activity
            android:name=".TelephonyDemo"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

    <uses-sdk android:minSdkVersion="7" />

</manifest>

My layout is :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Telephony Demo"
        android:textSize="22sp" />

    <TextView
        android:id="@+id/textOut"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Output" >
    </TextView>

</LinearLayout>

Answer 1

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

    /* permission should be added like below*/
    <uses-permission android:name="android.permission.READ_PHONE_STATE"/>

    <application
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.Light" >
        <activity
            android:name=".TelephonyDemo"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

    <uses-sdk android:minSdkVersion="7" />

</manifest>

Answer 2

Your application knows PHONE STATE thanks an Intent that is Broadcasted by the Telephony Service notifying to application about PHONE STATE changes.
You may need Guide line to create your application

• Intent : see http://developer.android.com/reference/android/content/Intent.html for details and see http://developer.android.com/guide/topics/intents/intents-filters.html for concept and TelephonyManager.ACTION_PHONE_STATE_CHANGED is the name of the intent you need to receives thanks your BoradCastReceiver
• BroadcastReceiver http://developer.android.com/reference/android/content/BroadcastReceiver.html and see http://developer.android.com/guide/topics/fundamentals.html at "Application Component" Section

• android.permission.READ_PHONE_STATE permission have to be added in your AndroidManifest.xml file (here an example extract..)

  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
  
       package="xyz...."
       android:versionCode="1" android:versionName="0.1">
       <uses-sdk android:minSdkVersion="7" />
       <uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
  
   ...
  </manifest>
  

Answer 3

I did not see <uses-permission android:name="android.permission.READ_PHONE_STATE" /> in your Manifest file.

It is required for your application to be able to read that state.