Added in API level 28

Builder

open class Builder
kotlin.Any
   ↳ android.hardware.biometrics.BiometricPrompt.Builder

A builder that collects arguments to be shown on the system-provided biometric dialog.

Summary

Public constructors
Builder(context: Context!)

Creates a builder for a BiometricPrompt dialog.

Public methods
open BiometricPrompt

Creates a BiometricPrompt.

open BiometricPrompt.Builder
setAllowedAuthenticators(authenticators: Int)

Optional: Specifies the type(s) of authenticators that may be invoked by BiometricPrompt to authenticate the user.

open BiometricPrompt.Builder
setConfirmationRequired(requireConfirmation: Boolean)

Optional: Sets a hint to the system for whether to require user confirmation after authentication.

open BiometricPrompt.Builder

Optional: Sets a description that will be shown on the prompt.

open BiometricPrompt.Builder

Optional: If enabled, the user will be given the option to authenticate with their device PIN, pattern, or password.

open BiometricPrompt.Builder

Required: Sets the text, executor, and click listener for the negative button on the prompt.

open BiometricPrompt.Builder

Optional: Sets a subtitle that will be shown on the prompt.

open BiometricPrompt.Builder

Required: Sets the title that will be shown on the prompt.

Public constructors

Builder

Added in API level 28
Builder(context: Context!)

Creates a builder for a BiometricPrompt dialog.

Parameters
context Context!: The Context that will be used to build the prompt.

Public methods

build

Added in API level 28
open fun build(): BiometricPrompt

Creates a BiometricPrompt.

Return
BiometricPrompt An instance of BiometricPrompt. This value cannot be null.
Exceptions
java.lang.IllegalArgumentException If any required fields are unset, or if given any invalid combination of field values.

setAllowedAuthenticators

Added in API level 30
open fun setAllowedAuthenticators(authenticators: Int): BiometricPrompt.Builder

Optional: Specifies the type(s) of authenticators that may be invoked by BiometricPrompt to authenticate the user. Available authenticator types are defined in Authenticators and can be combined via bitwise OR. Defaults to:

If this method is used and no authenticator of any of the specified types is available at the time BiometricPrompt#authenticate(...) is called, authentication will be canceled and AuthenticationCallback#onAuthenticationError(int, CharSequence) will be invoked with an appropriate error code.

This method should be preferred over setDeviceCredentialAllowed(boolean) and overrides the latter if both are used. Using this method to enable device credential authentication (with Authenticators#DEVICE_CREDENTIAL) will replace the negative button on the prompt, making it an error to also call setNegativeButton(java.lang.CharSequence,java.util.concurrent.Executor,android.content.DialogInterface.OnClickListener).

If unlocking cryptographic operation(s), it is the application's responsibility to request authentication with the proper set of authenticators (e.g. match the authenticators specified during key generation).

Parameters
authenticators Int: A bit field representing all valid authenticator types that may be invoked by the prompt. Value is either 0 or a combination of android.hardware.biometrics.BiometricManager.Authenticators#BIOMETRIC_STRONG, android.hardware.biometrics.BiometricManager.Authenticators#BIOMETRIC_WEAK, android.hardware.biometrics.BiometricManager.Authenticators.BIOMETRIC_CONVENIENCE, and android.hardware.biometrics.BiometricManager.Authenticators#DEVICE_CREDENTIAL
Return
BiometricPrompt.Builder This builder. This value cannot be null.

setConfirmationRequired

Added in API level 29
open fun setConfirmationRequired(requireConfirmation: Boolean): BiometricPrompt.Builder

Optional: Sets a hint to the system for whether to require user confirmation after authentication. For example, implicit modalities like face and iris are passive, meaning they don't require an explicit user action to complete authentication. If set to true, these modalities should require the user to take some action (e.g. press a button) before AuthenticationCallback#onAuthenticationSucceeded(AuthenticationResult) is called. Defaults to true.

A typical use case for not requiring confirmation would be for low-risk transactions, such as re-authenticating a recently authenticated application. A typical use case for requiring confirmation would be for authorizing a purchase.

Note that this just passes a hint to the system, which the system may then ignore. For example, a value of false may be ignored if the user has disabled implicit authentication in Settings, or if it does not apply to a particular modality (e.g. fingerprint).

Parameters
requireConfirmation Boolean: true if explicit user confirmation should be required, or false otherwise.
Return
BiometricPrompt.Builder This builder. This value cannot be null.

setDescription

Added in API level 28
open fun setDescription(description: CharSequence): BiometricPrompt.Builder

Optional: Sets a description that will be shown on the prompt.

Note that the description set by Builder#setDescription(CharSequence) will be overridden by android.hardware.biometrics.BiometricPrompt.Builder#setContentView(android.hardware.biometrics.PromptContentView). The view provided to android.hardware.biometrics.BiometricPrompt.Builder#setContentView(android.hardware.biometrics.PromptContentView) will be used if both methods are called.

Parameters
description CharSequence: The description to display. This value cannot be null.
Return
BiometricPrompt.Builder This builder. This value cannot be null.

setDeviceCredentialAllowed

Added in API level 29
Deprecated in API level 30
open fun setDeviceCredentialAllowed(allowed: Boolean): BiometricPrompt.Builder

Deprecated: Replaced by setAllowedAuthenticators(int).

Optional: If enabled, the user will be given the option to authenticate with their device PIN, pattern, or password. Developers should first check android.hardware.biometrics.BiometricManager#canAuthenticate(int) for Authenticators#DEVICE_CREDENTIAL before enabling. If the device is not secured with a credential, AuthenticationCallback#onAuthenticationError(int, CharSequence) will be invoked with BiometricPrompt#BIOMETRIC_ERROR_NO_DEVICE_CREDENTIAL. Defaults to false.

Note that enabling this option replaces the negative button on the prompt with one that allows the user to authenticate with their device credential, making it an error to call setNegativeButton(java.lang.CharSequence,java.util.concurrent.Executor,android.content.DialogInterface.OnClickListener).

Parameters
allowed Boolean: true if the prompt should fall back to asking for the user's device credential (PIN/pattern/password), or false otherwise.
Return
BiometricPrompt.Builder This builder. This value cannot be null.

setNegativeButton

Added in API level 28
open fun setNegativeButton(
    text: CharSequence,
    executor: Executor,
    listener: DialogInterface.OnClickListener
): BiometricPrompt.Builder

Required: Sets the text, executor, and click listener for the negative button on the prompt. This is typically a cancel button, but may be also used to show an alternative method for authentication, such as a screen that asks for a backup password.

Note that this setting is not required, and in fact is explicitly disallowed, if device credential authentication is enabled via setAllowedAuthenticators(int) or setDeviceCredentialAllowed(boolean).

Parameters
text CharSequence: Text to be shown on the negative button for the prompt. This value cannot be null.
executor Executor: Executor that will be used to run the on click callback. This value cannot be null. Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
listener DialogInterface.OnClickListener: Listener containing a callback to be run when the button is pressed. This value cannot be null.
Return
BiometricPrompt.Builder This builder. This value cannot be null.

setSubtitle

Added in API level 28
open fun setSubtitle(subtitle: CharSequence): BiometricPrompt.Builder

Optional: Sets a subtitle that will be shown on the prompt.

Parameters
subtitle CharSequence: The subtitle to display. This value cannot be null.
Return
BiometricPrompt.Builder This builder. This value cannot be null.

setTitle

Added in API level 28
open fun setTitle(title: CharSequence): BiometricPrompt.Builder

Required: Sets the title that will be shown on the prompt.

Parameters
title CharSequence: The title to display. This value cannot be null.
Return
BiometricPrompt.Builder This builder. This value cannot be null.