Firebase addAuthStateListener not getting called in kotlin

Question

I'm trying to call addAuthStateListener but it's not working in kotlin. and also AuthUI not working properly. Every time I try to run this code I'm getting a runtime error. And the application force closed. I tried to get some help in firebase documentation but I'm not found anything that helps me.

import android.app.Activity
import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import com.firebase.ui.auth.AuthUI
import com.google.firebase.auth.FirebaseAuth

class MainActivity : AppCompatActivity() {
    private var mFirebaseAuth:FirebaseAuth? = null
    private var mFirebaseAuthLis:FirebaseAuth.AuthStateListener?=null
    private val RC_SIGN_IN = 1258
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        mFirebaseAuth = FirebaseAuth.getInstance()

        //val user = FirebaseAuth.getInstance().currentUser != null

        mFirebaseAuthLis=FirebaseAuth.AuthStateListener { firebaseAuth ->
            var user = firebaseAuth.currentUser
            if (user!=null){
                Toast.makeText(applicationContext,"Welcome",Toast.LENGTH_SHORT).show()
            }else{
                val providers = arrayListOf(
                    AuthUI.IdpConfig.EmailBuilder().build(),
                    AuthUI.IdpConfig.PhoneBuilder().build(),
                    AuthUI.IdpConfig.GoogleBuilder().build(),
                    AuthUI.IdpConfig.FacebookBuilder().build(),
                    AuthUI.IdpConfig.TwitterBuilder().build())


                startActivityForResult(
                    AuthUI.getInstance()
                        .createSignInIntentBuilder()
                        .setAvailableProviders(providers)
                        .build(),
                    RC_SIGN_IN)
            }

        }

    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode==RC_SIGN_IN){
            if (resultCode== Activity.RESULT_OK){
                Toast.makeText(applicationContext,"Hi user",Toast.LENGTH_SHORT).show()
            }else{
                finish()
            }
        }
    }

    override fun onStart() {
        super.onStart()
       mFirebaseAuth!!.addAuthStateListener { mFirebaseAuthLis }
    }

    override fun onPause() {
        super.onPause()
       mFirebaseAuth!!.removeAuthStateListener { mFirebaseAuthLis }
    }
}

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.roni.familychatting">

    <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>
    </application>

</manifest>

build.gradle(Module: app)

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.roni.familychatting"
        minSdkVersion 21
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    //implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.google.firebase:firebase-core:16.0.4'
    implementation 'com.google.firebase:firebase-auth:16.0.4'
    implementation 'com.android.support:appcompat-v7:24.2.0'
    implementation 'com.firebaseui:firebase-ui-auth:4.2.0'

    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'

    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}
apply plugin: 'com.google.gms.google-services'

project level gradle

buildscript {
    ext.kotlin_version = '1.2.71'
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.0.1'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Answer 1

You need to register the listener:

FirebaseAuth.getInstance().addAuthStateListener(listener)

In your case:

mFirebaseAuth!!.addAuthStateListener(mFirebaseAuthLis)

Answer 2

You need to save FirebaseAuth.AuthStateListener in mFirebaseAuthLis

mFirebaseAuthLis = FirebaseAuth.AuthStateListener { firebaseAuth ->
        var user = firebaseAuth.currentUser
        if (user!=null){
            Toast.makeText(applicationContext,"Welcome",Toast.LENGTH_SHORT).show()
        } else{
            val providers = arrayListOf(
                AuthUI.IdpConfig.EmailBuilder().build(),
                AuthUI.IdpConfig.PhoneBuilder().build(),
                AuthUI.IdpConfig.GoogleBuilder().build(),
                AuthUI.IdpConfig.FacebookBuilder().build(),
                AuthUI.IdpConfig.TwitterBuilder().build())


            startActivityForResult(
                AuthUI.getInstance()
                    .createSignInIntentBuilder()
                    .setAvailableProviders(providers)
                    .build(),
                RC_SIGN_IN)
        }

    }

After that all should work as expected.