Simple Example of Firebase Authentication in Kotlin

Here is the simple example of Authentication process using Firebase in Kotlin Programming Language.

Step 1.

Login into Firebase Console and create your project.

Step 2.

Navigate into Authentication and enable your preferred login methods.

Step 3.

Create your Android project and add the following classpath into root of the project's build.gradle.

classpath 'com.google.gms:google-services:3.1.1'

Step 4.

And then add the following plugin into your module's build.gradle.

apply plugin: 'com.google.gms.google-services'

Step 5.

And then add the following dependency into your module's build.gradle.

implementation 'com.firebaseui:firebase-ui-auth:3.3.1'

That's you wanted to access the Firebase's Authentication API in your project.
Here is the methods to Sign In, Sign Out and delete the account.

Sign In

private fun signIn() {
    // Choose authentication providers
    val providers = Arrays.asList(AuthUI.IdpConfig.GoogleBuilder().build(),
            AuthUI.IdpConfig.PhoneBuilder().build(),
            AuthUI.IdpConfig.EmailBuilder().build())

    // Create and launch sign-in intent
    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) {
        val response = IdpResponse.fromResultIntent(data)

        if (resultCode == RESULT_OK) {
            // Successfully signed in
        } else {
            // Sign in failed, check response for error code
        }
    }
}

Sign Out

private fun signOut() {
    AuthUI.getInstance()
                .signOut(this)
                .addOnCompleteListener { task ->
                    if (task.isSuccessful) {
                        Toast.makeText(activity, getString(R.string.signed_out), LENGTH_LONG).show()
                    }
                }
}

Delete

private fun delete() {
    AuthUI.getInstance()
                .delete(this)
                .addOnCompleteListener { task ->
                    if (task.isSuccessful) {
                        Toast.makeText(activity, getString(R.string.deleted), LENGTH_LONG).show()
                    }
                 }
}

Screenshot

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Source code on GitHub

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