Erik Ivares Erik Ivares - 8 months ago 331
Java Question

How do I access ReactContext from Java code in React Native?

I an trying to create an application thet will catch the incoming calls to the cellphone using a BroadcastReciver. From my BroadcastReciver i whould like to sent the number as an event to my JS file using this method.

I have checked that my Java code is working and is catching the calls and number but my application craches with the error that mentions that the react context is null. I am guessing that this is because the manifest (or something) is creating a new instance of the class when the event from the android system is catched and that the new instance does not have a ReactContext. Is there any way to access the ReactContext from the Java code or send a ReactContext to the BroadcastReciver through the manifest?

This is my BroadcastReciver:

package com.bridgetest;

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

import com.facebook.react.modules.core.DeviceEventManagerModule;
import com.facebook.react.bridge.JavaScriptModule;

import android.widget.Toast;

import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.WritableMap;
import com.facebook.react.bridge.Arguments;

import javax.annotation.Nullable;

* Created by Erik on 2016-04-06.
public class BroadcastReceiverCustom extends BroadcastReceiver {

ReactContext reactContext;

public BroadcastReceiverCustom (){

public void onReceive(Context context, Intent intent) {
if (intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(TelephonyManager.EXTRA_STATE_RINGING)) {
// This code will execute when the phone has an incoming call

// get the phone number
String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
Toast.makeText(context, "Call from:" +incomingNumber, Toast.LENGTH_LONG).show();

} else if (intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
|| intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
TelephonyManager.EXTRA_STATE_OFFHOOK)) {
// This code will execute when the call is disconnected
Toast.makeText(context, "Detected call hangup event", Toast.LENGTH_LONG).show();

public void sendCallEvent(String incomingNumber){
WritableMap params = Arguments.createMap();
params.putString("Number", incomingNumber);
sendEvent("CallRecevied", params);

private void sendEvent(String eventName,
@Nullable WritableMap params) {
.emit(eventName, params);


I solved the problem. I created a ReactContextBasseJavaModule with a singleton pattern and got access to ReactContext through it (This might be a huge "nono").

If there is another smarter way to solve this problem please inform me.