Exception in HostObject::get(propName:RNfirebase) - firebase

Question

I am learning how to implement Firestore with react-native(Android). Then, I found 'react-native-firebase' and stuck in this exception.
Error:Exception in
HostObject::get(propName:RNFirebase):
java.lang.NoClassDefFoundError: Failed resolution
of: Lcom/google/firebase/FirebaseApp;
I already setup firebase in my gradle (ref.https://firebase.google.com/docs/android/setup/?authuser=0)
Firebase database's rule
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, write;
}
}
}
and this is my learning code (ref.https://www.youtube.com/watch?v=_GOI7h9ojr8)
import React,{ Component } from 'react';
import {
Flatlist,
Text,
TextInput,
TouchableHighlight,
Image,
View } from 'react-native';
import firebase from 'react-native-firebase';
export default class test extends Component {
constructor(props){
super(props);
this.state = ({
todoTask: [],
newTaskName: '',
loading: false
});
this.ref = firebase.firestore().collection('todo');
}
onPressAdd = () => {
this.ref.add({
taskName: this.state.newTaskName
}).then((data) => {
console.log('added data = ${data}');
this.setState({
newTaskName: '',
loading: true
});
}).catch((error) => {
console.log('error adding firestore document = ${error}');
this.setState({
newTaskName: '',
loading: true
});
});
}
render(){
return (
<View style={{flex: 1}}>
<Text>Hello</Text>
<TextInput style={{
height: 40,
width: 200,
margin: 10,
padding: 10,
borderColor: 'white',
borderWidth: 1,
color: 'white'
}}
keyboardType='default'
placeholderTextColor='white'
placeholder='Enter task name'
onChangeText={
(text) => {
this.setState({ newTaskName: text});
}
}
>
</TextInput>
<TouchableHighlight
style={{ marginRight: 10 }}
underlayColor='tomato'
onPress={this.onPressAdd}>
<Image
style={{ width: 35, height: 35 }}
source={require('./icon-add.png')}
>
</Image>
</TouchableHighlight>
<Flatlist
data={this.state.todoTask}
renderItem={({item, index}) => {
return(
<Text>{item.taskName}</Text>
);
}}
>
</Flatlist>
</View>
);
}
}
Can u explain why it happen? Thanks a lot.

Answer 1

You installed 'react-native-firebase' package so kindly note to remove(uninstall) it.
According to the docs:
First you need to install firebase package:
npm install --save firebase
Then import it using firebase/app:
// Firebase App (the core Firebase SDK) is always required and
// must be listed before other Firebase SDKs
import * as firebase from "firebase/app";

Answer 2

Also making sure you have the library you are using in your android/app/build.gradle in my case firebase-core
implementation "com.google.firebase:firebase-core:17.4.3"