android: background phone state monitoring

Question

I'm trying to create a background process which monitors the phone state and displays a toast message if the state is changed. so far, ive implemented these, but when i install and run. It does nothing. It wont display anything. Im posting my codes here. pls help me out.

StateMonitor.java

`

import android.content.Context;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.widget.Toast;

public class PhoneStateMonitor extends PhoneStateListener {
    Context context;

    public PhoneStateMonitor(Context context) {
        super();
        // TODO Auto-generated constructor stub
        this.context=context;
    }

    //This Method Automatically called when changes is detected in Phone State
    public void onCallStateChanged(int state, String incomingNumber) {
        // TODO Auto-generated method stub
        super.onCallStateChanged(state, incomingNumber);

        Toast.makeText(context, "Phone State - "+state+" Incoming Number - "+incomingNumber, Toast.LENGTH_LONG).show();//Giving the Message that Phone State Changed
        //Checking The phone state  
        switch(state)
        {
        case TelephonyManager.CALL_STATE_IDLE:    //Phone is in Idle State
            Toast.makeText(context, "Phone State is IDLE", Toast.LENGTH_LONG).show();
            break;
        case TelephonyManager.CALL_STATE_RINGING:  //Phone is Ringing
            Toast.makeText(context, "Phone State is RINGING", Toast.LENGTH_LONG).show();
            break;
        case TelephonyManager.CALL_STATE_OFFHOOK:  //Call is Received
            Toast.makeText(context, "Call State is OFFHOOK",Toast.LENGTH_LONG).show();
            break;
        }
    }
}
`

PhoneReceiver.java

`import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
//Automatically called when State Change is Detected because this Receiver is Registered for PHONE_STATE intent filter in AndroidManifest.xml
public class PhoneStateReceiver extends BroadcastReceiver {

    TelephonyManager manager;       
    PhoneStateMonitor phoneStateListener;
    static boolean isAlreadyListening=false;

    //This Method automatically Executed when Phone State Change is Detected
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        phoneStateListener =new PhoneStateMonitor(context);//Creating the Object of Listener
        manager=(TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE);//Getting the Telephony Service Object
        if(!isAlreadyListening)//Checking Listener is Not Registered with Telephony Services
        {
              manager.listen(phoneStateListener, PhoneStateListener.LISTEN_CALL_STATE);//Registering the Listener with Telephony to listen the State Change
          isAlreadyListening=true;  //setting true to indicate that Listener is listening the Phone State
        }

    }

}
`

Android Manifest.xml

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

    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="21" />

<uses-permission android:name="android.permission.READ_PHONE_STATE" /><!-- Permission for Reading Phone State -->
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >

        <!--  If this app is not running then this will be automatically called when phone state change detected(Look at Intent Filter) -->
        <receiver android:name=".PhoneStateReceiver">
            <intent-filter>
                <action android:name="android.intent.action.PHONE_STATE"/>
            </intent-filter>
            </receiver>
    </application>

</manifest>`

When i install from eclipse , it says apk installed. When i call my phone, Toast message doesnt pop up. where am i going wrong? please help! thanks!

Answer 1

When you install the app, it stays in stopped state until you start the application with some UI control (i.e. Activity). It became compulsory from Android 3.1 APIs (API 12).

So ultimately, you need at least one Activity in your application apart from just BroadcastReceiver to move your app out of that stopped state. Otherwise it will not receive any broadcasts.

Reference:

Launch Controls