Incoming Call Blocking When App is Open

I have successfully implemented the code for blocking call but it is blocking all the calls even if I closed the application. I need to block the call when a specific activity is opened(if it is not possible the block call when app is open also ok). I am attaching my code below. please go through it. For any positive response thanks in advance.

BlockCallReceiver.java

import java.lang.reflect.Method;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.TelephonyManager;

public class BlockCallReceiver extends BroadcastReceiver{
    Context context;
    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        Bundle myBundle = intent.getExtras();
        if (myBundle != null)
        {
            System.out.println("--------Not null-----");
            try
            {
                if (intent.getAction().equals("android.intent.action.PHONE_STATE"))
                {
                    String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
                    System.out.println("--------in state-----");
                    if (state.equals(TelephonyManager.EXTRA_STATE_RINGING))
                    {
                        // Incoming call
                        String incomingNumber =intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
                        System.out.println("--------------my number---------"+incomingNumber);

// this is main section of the code,. could also be use for particular number.
                        // Get the boring old TelephonyManager.
                        TelephonyManager telephonyManager =(TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);

                        // Get the getITelephony() method
                        Class<?> classTelephony = Class.forName(telephonyManager.getClass().getName());
                        Method methodGetITelephony = classTelephony.getDeclaredMethod("getITelephony");

                        // Ignore that the method is supposed to be private
                        methodGetITelephony.setAccessible(true);

                        // Invoke getITelephony() to get the ITelephony interface
                        Object telephonyInterface = methodGetITelephony.invoke(telephonyManager);

                        // Get the endCall method from ITelephony
                        Class<?> telephonyInterfaceClass = Class.forName(telephonyInterface.getClass().getName());
                        Method methodEndCall = telephonyInterfaceClass.getDeclaredMethod("endCall");

                        // Invoke endCall()
                        methodEndCall.invoke(telephonyInterface);

                    }

                }
            }
            catch (Exception ex)
            { // Many things can go wrong with reflection calls
                ex.printStackTrace();
            }
        }
    }
}

MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import com.karan.churi.PermissionManager.PermissionManager;

import java.lang.reflect.Method;

public class MainActivity extends AppCompatActivity {
    PermissionManager permission;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        permission=new PermissionManager() {};
        permission.checkAndRequestPermissions(this);
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.arjun.myapplication">
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.MODIFY_PHONE_STATE" />
    <uses-permission android:name="android.permission.CALL_PHONE" />
    <uses-feature
        android:name="android.hardware.telephony"
        android:required="false" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver android:name=".BlockCallReceiver" >
            <intent-filter android:priority="100" >
                <action android:name="android.intent.action.PHONE_STATE" >
                </action>
            </intent-filter>
        </receiver>
    </application>

</manifest>

You need to initialize a BroadcastReceiver in your MainActivity like the following.

private final BroadcastReceiver mBloackCallReceiver = new BlockCallReceiver();

Then register the BroadcastReceiver using the code below in the onCreate function of your activity.

registerReceiver(mBloackCallReceiver , new IntentFilter(TelephonyManager.ACTION_PHONE_STATE_CHANGED));

Remember to unregister the BroadcastReceiver using the code below in the onDestroy function of your activity.

unregisterReceiver(mybroadcast);

Remove the receiver tag from your AndroidManifest.xml.