Change Firebase Password | Android Studio | Kotlin

How to change the password of an account on Firebase?

In this tutorial, we will programmatically update/change the password of an existing email/password account on Firebase using Android Studio IDE and Kotlin language.

First of all, we will reauthenticate the user by authenticating the old/previous password, if that password is correct then input a new password to update.

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Required Libraries:

dependencies {
    .
    . 
    .
    //firebase libs
    implementation 'com.google.firebase:firebase-auth:19.2.0'
    implementation 'com.google.firebase:firebase-core:17.2.3'
    .
    .
    .
}

ctivity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FAF9F9"
    android:gravity="center"
    android:padding="10dp"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/labelTv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="Update Password"
        android:textAlignment="center"
        android:textColor="#000"
        android:textSize="25sp"
        android:textStyle="bold" />

    <EditText
        android:id="@+id/oldPassEt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/labelTv"
        android:layout_marginTop="40dp"
        android:background="#fff"
        android:hint="Old Password"
        android:inputType="textPassword"
        android:padding="10dp" />

    <EditText
        android:id="@+id/newPassEt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/oldPassEt"
        android:layout_marginTop="10dp"
        android:background="#fff"
        android:hint="New Password"
        android:inputType="textPassword"
        android:padding="10dp" />

    <Button
        android:id="@+id/updatePasswordBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/newPassEt"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="Update Password" />

</RelativeLayout>

MainActivity.kt

package com.blogspot.atifsoftwares.myapplication

import android.app.ProgressDialog
import android.os.Bundle
import android.text.TextUtils
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.firebase.auth.EmailAuthProvider
import com.google.firebase.auth.FirebaseAuth
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    private lateinit var firebaseAuth: FirebaseAuth
    private lateinit var pd: ProgressDialog

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        //init FirebaseAuth for use authentication
        firebaseAuth = FirebaseAuth.getInstance()
        //setup progress dialog
        pd = ProgressDialog(this)
        pd.setMessage("Please Wait...")
        //handle click event to begin
        updatePasswordBtn.setOnClickListener {
            //input data
            val oldPassword = oldPassEt.text.toString().trim()
            val newPassword = newPassEt.text.toString().trim()
            //validate data
            if (TextUtils.isEmpty(oldPassword)) {
                Toast.makeText(applicationContext, "Enter your current password...", Toast.LENGTH_SHORT).show()
            } else if (newPassword.length < 6) {
                Toast.makeText(applicationContext, "Password length must atleast 6 characters...", Toast.LENGTH_SHORT).show()
            } else {
                updatePassword(oldPassword, newPassword)
            }
        }
    }

    private fun updatePassword(oldPassword: String, newPassword: String) {
        //show dialog
        pd.show()
        //get current user
        val user = firebaseAuth.currentUser
        //before changing password re-authenticate the user
        val authCredential = EmailAuthProvider.getCredential(user!!.email!!, oldPassword)
        user.reauthenticate(authCredential)
                .addOnSuccessListener {
                    //successfully authenticated, begin update
                    user.updatePassword(newPassword)
                            .addOnSuccessListener {
                                //password updated
                                pd.dismiss()
                                Toast.makeText(applicationContext, "Password Updated...", Toast.LENGTH_SHORT).show()
                            }
                            .addOnFailureListener { e ->
                                //failed updating password, show reason
                                pd.dismiss()
                                Toast.makeText(applicationContext, "" + e.message, Toast.LENGTH_SHORT).show()
                            }
                }
                .addOnFailureListener { e ->
                    //authentication failed, show reason
                    pd.dismiss()
                    Toast.makeText(applicationContext, "" + e.message, Toast.LENGTH_SHORT).show()
                }
    }
    
}

Output