Question

The code that I am presently using is as follows:

My main class

  public class Index extends  BroadcastReceiver{ 

        @Override
        public void onReceive(Context context, Intent intent) {

            TelephonyManager telephonyManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
            telephonyManager.listen(new CustomPhoneStateListener(context), PhoneStateListener.LISTEN_CALL_STATE);
        }
    }

the CustomPhoneStateListener class

    public class CustomPhoneStateListener extends PhoneStateListener {

        public  Activity activ=new Activity(){
            public void startActivity(Intent i) {}
            };
            Context context; 
        public CustomPhoneStateListener(Context context) {
            super();
            this.context = context;
        }
        @Override
        public void onCallStateChanged(int state, String incomingNumber) {
            super.onCallStateChanged(state, incomingNumber);
           switch (state) {
            case TelephonyManager.CALL_STATE_IDLE:

                Toast.makeText(context, "call has ended", Toast.LENGTH_SHORT).show();
    // The process to transfer to the next application. 
                    Intent i = new Intent(Intent.ACTION_MAIN);
                PackageManager manager = activ.getPackageManager();
i = manager.getLaunchIntentForPackage("com.timetracker.app");// package  name for my new app
                i.addCategory(Intent.CATEGORY_LAUNCHER);
                activ.startActivity(i);
                break;
        case TelephonyManager.CALL_STATE_OFFHOOK:

                Toast.makeText(context, "Phone call has taken", Toast.LENGTH_SHORT).show();
                break;
            case TelephonyManager.CALL_STATE_RINGING:

                //when Ringing
                Toast.makeText(context, "Phone is ringing", Toast.LENGTH_SHORT).show();
                break;
                default:
                break;
            }
        }
    }

and the Android Manifest file as:

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

    <application android:icon="@drawable/icon" android:label="@string/app_name">
                <receiver android:name=".Index" >
                  <intent-filter>
               <action android:name="android.intent.action.PHONE_STATE"/>
               <action android:name="android.view.InputMethod" /> 
                </intent-filter>
                </receiver>
</application>

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

By using the above code I am able to get the toast message for the respective actions that I am performing ,but I am not able to give any Intent or by using the Package_Manger I am not able to shift to the next app.

The log_cat message returned when trying to execute the code for invoking the app:

 D/AndroidRuntime(312): Shutting down VM
: W/dalvikvm(312): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
 FATAL EXCEPTION: main
  E/AndroidRuntime(312): java.lang.NullPointerException 
  E/AndroidRuntime(312):    at android.content.ContextWrapper.getPackageManager(ContextWrapper.java:85)
  E/AndroidRuntime(312):    at com.android.call.CustomPhoneStateListener.onCallStateChanged(CustomPhoneStateListener.java:39)
  E/AndroidRuntime(312):    at android.telephony.PhoneStateListener$2.handleMessage(PhoneStateListener.java:319)
  E/AndroidRuntime(312):    at android.os.Handler.dispatchMessage(Handler.java:99)
  E/AndroidRuntime(312):    at android.os.Looper.loop(Looper.java:123)
  E/AndroidRuntime(312):    at android.app.ActivityThread.main(ActivityThread.java:4627)
  E/AndroidRuntime(312):    at java.lang.reflect.Method.invokeNative(Native Method)
  E/AndroidRuntime(312):    at java.lang.reflect.Method.invoke(Method.java:521)
  E/AndroidRuntime(312):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
   E/AndroidRuntime(312):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
   E/AndroidRuntime(312):   at dalvik.system.NativeStart.main(Native Method)

Answer 1

It looks like the problem is coming from the use of active declared like this:

    public  Activity activ=new Activity(){
        public void startActivity(Intent i) {}
    };

Here you’re creating a new Activity without a context. Maybe you should just pass the Activity right into your CustomPhoneStateListener instead of the Context. Or use the context to get the PackageManager:

PackageManager manager = context.getPackageManager();