Preventing hardware back button android for React Native

You need to return true, if you want to disable the default back button behavior.

Here is a sample component which will block the user from going back to previous screen.

import React, {Component,} from 'react';
import {
    View,
    Text,
    BackHandler,
    ToastAndroid,
} from 'react-native';

class BackButtonDemo extends Component {
    componentDidMount() {
        BackHandler.addEventListener('hardwareBackPress', this.handleBackButton);
    }

    componentWillUnmount() {
        BackHandler.removeEventListener('hardwareBackPress', this.handleBackButton);
    }

    handleBackButton() {
        ToastAndroid.show('Back button is pressed', ToastAndroid.SHORT);
        return true;
    }

    render() {
        return (
            <View>
                <Text>Back button example</Text>
            </View>
        );
    }
}

module.exports = BackButtonDemo;

Note:

Also remove this.props.navigator.pop(); from your solution.

Navigator pop function will take the user to the previous screen rendered by Navigator.

Shiny new implementation using react hooks:

import React, {Component, useEffect} from 'react';
import {
    View,
    Text,
    BackHandler,
} from 'react-native';

const LogInView = () => {

    useEffect(() => {
      const backHandler = BackHandler.addEventListener('hardwareBackPress', () => true)
      return () => backHandler.remove()
    }, [])

    return (
        <View>
            <Text>Back button example</Text>
        </View>
    );
}

export default LoginView

I disable my back button (android) for whole application by add this code in App.js

componentDidMount() {
  BackAndroid.addEventListener('hardwareBackPress', this.handleBackButton);
}

componentWillUnmount() {
  BackAndroid.removeEventListener('hardwareBackPress', this.handleBackButton);
}

handleBackButton() {
  return true;
}

don't forget to import BackAndroid

import {BackAndroid} from 'react-native'

Try this Disable back button by just returning true

import {BackAndroid} from 'react-native';

componentWillMount() {
   BackAndroid.addEventListener('hardwareBackPress', () => {return true});
} 

using the BackHandler from react native worked for me. Just include this line in your ComponentWillMount:

BackHandler.addEventListener('hardwareBackPress', function() {return true})

it will disable back button on android device.