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Summary: Nested Classes | Constants | Methods | Inherited Methods

# BiometricPrompt

`public class BiometricPrompt`
`extends Object` ``

java.lang.Object
↳ | android.hardware.biometrics.BiometricPrompt

A class that manages a system-provided biometric dialog.

## Summary

### Nested classes
`class` | `BiometricPrompt.AuthenticationCallback` Callback structure provided to `BiometricPrompt#authenticate(CancellationSignal, Executor, AuthenticationCallback)` or `BiometricPrompt#authenticate(CryptoObject, CancellationSignal, Executor, AuthenticationCallback)`.
`class` | `BiometricPrompt.AuthenticationResult` Container for callback data from `BiometricPrompt.authenticate(android.os.CancellationSignal, java.util.concurrent.Executor, android.hardware.biometrics.BiometricPrompt.AuthenticationCallback)` and `BiometricPrompt.authenticate(android.hardware.biometrics.BiometricPrompt.CryptoObject, android.os.CancellationSignal, java.util.concurrent.Executor, android.hardware.biometrics.BiometricPrompt.AuthenticationCallback)`.
`class` | `BiometricPrompt.Builder` A builder that collects arguments to be shown on the system-provided biometric dialog.
`class` | `BiometricPrompt.CryptoObject` A wrapper class for the cryptographic operations supported by BiometricPrompt.

### Constants
`int` | `AUTHENTICATION_RESULT_TYPE_BIOMETRIC` Authentication type reported by `AuthenticationResult` when the user authenticated by presenting some form of biometric (e.g. fingerprint or face).
`int` | `AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL` Authentication type reported by `AuthenticationResult` when the user authenticated by entering their device PIN, pattern, or password.
`int` | `BIOMETRIC_ACQUIRED_GOOD` The image acquired was good.
`int` | `BIOMETRIC_ACQUIRED_IMAGER_DIRTY` The biometric image was too noisy due to suspected or detected dirt on the sensor.
`int` | `BIOMETRIC_ACQUIRED_INSUFFICIENT` The biometric image was too noisy to process due to a detected condition or a possibly dirty sensor (See `BIOMETRIC_ACQUIRED_IMAGER_DIRTY`).
`int` | `BIOMETRIC_ACQUIRED_PARTIAL` Only a partial biometric image was detected.
`int` | `BIOMETRIC_ACQUIRED_TOO_FAST` The biometric image was incomplete due to quick motion.
`int` | `BIOMETRIC_ACQUIRED_TOO_SLOW` The biometric image was unreadable due to lack of motion.
`int` | `BIOMETRIC_ERROR_CANCELED` The operation was canceled because the biometric sensor is unavailable.
`int` | `BIOMETRIC_ERROR_HW_NOT_PRESENT` The device does not have a biometric sensor.
`int` | `BIOMETRIC_ERROR_HW_UNAVAILABLE` The hardware is unavailable.
`int` | `BIOMETRIC_ERROR_LOCKOUT` The operation was canceled because the API is locked out due to too many attempts.
`int` | `BIOMETRIC_ERROR_LOCKOUT_PERMANENT` The operation was canceled because BIOMETRIC_ERROR_LOCKOUT occurred too many times.
`int` | `BIOMETRIC_ERROR_NO_BIOMETRICS` The user does not have any biometrics enrolled.
`int` | `BIOMETRIC_ERROR_NO_DEVICE_CREDENTIAL` The device does not have pin, pattern, or password set up.
`int` | `BIOMETRIC_ERROR_NO_SPACE` Error state returned for operations like enrollment; the operation cannot be completed because there's not enough storage remaining to complete the operation.
`int` | `BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED` A security vulnerability has been discovered and the sensor is unavailable until a security update has addressed this issue.
`int` | `BIOMETRIC_ERROR_TIMEOUT` Error state returned when the current request has been running too long.
`int` | `BIOMETRIC_ERROR_UNABLE_TO_PROCESS` Error state returned when the sensor was unable to process the current image.
`int` | `BIOMETRIC_ERROR_USER_CANCELED` The user canceled the operation.
`int` | `BIOMETRIC_ERROR_VENDOR` OEMs should use this constant if there are conditions that do not fit under any of the other publicly defined constants, and must provide appropriate strings for these errors to the `BiometricPrompt.AuthenticationCallback#onAuthenticationError(int, CharSequence)` callback.

### Public methods
`void` | `authenticate(CancellationSignal cancel, Executor executor, BiometricPrompt.AuthenticationCallback callback)` This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric.
`void` | `authenticate(BiometricPrompt.CryptoObject crypto, CancellationSignal cancel, Executor executor, BiometricPrompt.AuthenticationCallback callback)` This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric.
`int` | `getAllowedAuthenticators()` Gets the type(s) of authenticators that may be invoked by the prompt to authenticate the user, as set by `Builder#setAllowedAuthenticators(int)`.
`CharSequence` | `getDescription()` Gets the description for the prompt, as set by `Builder#setDescription(CharSequence)`.
`CharSequence` | `getNegativeButtonText()` Gets the negative button text for the prompt, as set by `Builder#setNegativeButton(CharSequence, Executor, DialogInterface.OnClickListener)`.
`CharSequence` | `getSubtitle()` Gets the subtitle for the prompt, as set by `Builder#setSubtitle(CharSequence)`.
`CharSequence` | `getTitle()` Gets the title for the prompt, as set by `Builder#setTitle(CharSequence)`.
`boolean` | `isConfirmationRequired()` Determines if explicit user confirmation is required by the prompt, as set by `Builder#setConfirmationRequired(boolean)`.

### Inherited methods
From class `java.lang.Object`
`Object` | `clone()` Creates and returns a copy of this object.
`boolean` | `equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void` | `finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>` | `getClass()` Returns the runtime class of this `Object`.
`int` | `hashCode()` Returns a hash code value for the object.
`final void` | `notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void` | `notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String` | `toString()` Returns a string representation of the object.
`final void` | `wait(long timeout, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void` | `wait(long timeout)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void` | `wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

## Constants

### AUTHENTICATION_RESULT_TYPE_BIOMETRIC

    public static final int AUTHENTICATION_RESULT_TYPE_BIOMETRIC

Authentication type reported by `AuthenticationResult` when the user authenticated by presenting some form of biometric (e.g. fingerprint or face).

Constant Value: 2 (0x00000002)

### AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL

    public static final int AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL

Authentication type reported by `AuthenticationResult` when the user authenticated by entering their device PIN, pattern, or password.

Constant Value: 1 (0x00000001)

### BIOMETRIC_ACQUIRED_GOOD

    public static final int BIOMETRIC_ACQUIRED_GOOD

The image acquired was good.

Constant Value: 0 (0x00000000)

### BIOMETRIC_ACQUIRED_IMAGER_DIRTY

    public static final int BIOMETRIC_ACQUIRED_IMAGER_DIRTY

The biometric image was too noisy due to suspected or detected dirt on the sensor. For example, it's reasonable return this after multiple `BIOMETRIC_ACQUIRED_INSUFFICIENT` or actual detection of dirt on the sensor (stuck pixels, swaths, etc.). The user is expected to take action to clean the sensor when this is returned.

Constant Value: 3 (0x00000003)

### BIOMETRIC_ACQUIRED_INSUFFICIENT

    public static final int BIOMETRIC_ACQUIRED_INSUFFICIENT

The biometric image was too noisy to process due to a detected condition or a possibly dirty sensor (See `BIOMETRIC_ACQUIRED_IMAGER_DIRTY`).

Constant Value: 2 (0x00000002)

### BIOMETRIC_ACQUIRED_PARTIAL

    public static final int BIOMETRIC_ACQUIRED_PARTIAL

Only a partial biometric image was detected. During enrollment, the user should be informed on what needs to happen to resolve this problem, e.g. "press firmly on sensor." (for fingerprint)

Constant Value: 1 (0x00000001)

### BIOMETRIC_ACQUIRED_TOO_FAST

    public static final int BIOMETRIC_ACQUIRED_TOO_FAST

The biometric image was incomplete due to quick motion. For example, this could also happen if the user moved during acquisition. The user should be asked to repeat the operation more slowly.

Constant Value: 5 (0x00000005)

### BIOMETRIC_ACQUIRED_TOO_SLOW

    public static final int BIOMETRIC_ACQUIRED_TOO_SLOW

The biometric image was unreadable due to lack of motion.

Constant Value: 4 (0x00000004)

### BIOMETRIC_ERROR_CANCELED

    public static final int BIOMETRIC_ERROR_CANCELED

The operation was canceled because the biometric sensor is unavailable. For example, this may happen when the user is switched, the device is locked or another pending operation prevents or disables it.

Constant Value: 5 (0x00000005)

### BIOMETRIC_ERROR_HW_NOT_PRESENT

    public static final int BIOMETRIC_ERROR_HW_NOT_PRESENT

The device does not have a biometric sensor.

Constant Value: 12 (0x0000000c)

### BIOMETRIC_ERROR_HW_UNAVAILABLE

    public static final int BIOMETRIC_ERROR_HW_UNAVAILABLE

The hardware is unavailable. Try again later.

Constant Value: 1 (0x00000001)

### BIOMETRIC_ERROR_LOCKOUT

    public static final int BIOMETRIC_ERROR_LOCKOUT

The operation was canceled because the API is locked out due to too many attempts. This occurs after 5 failed attempts, and lasts for 30 seconds.

Constant Value: 7 (0x00000007)

### BIOMETRIC_ERROR_LOCKOUT_PERMANENT

    public static final int BIOMETRIC_ERROR_LOCKOUT_PERMANENT

The operation was canceled because BIOMETRIC_ERROR_LOCKOUT occurred too many times. Biometric authentication is disabled until the user unlocks with strong authentication (PIN/Pattern/Password)

Constant Value: 9 (0x00000009)

### BIOMETRIC_ERROR_NO_BIOMETRICS

    public static final int BIOMETRIC_ERROR_NO_BIOMETRICS

The user does not have any biometrics enrolled.

Constant Value: 11 (0x0000000b)

### BIOMETRIC_ERROR_NO_DEVICE_CREDENTIAL

    public static final int BIOMETRIC_ERROR_NO_DEVICE_CREDENTIAL

The device does not have pin, pattern, or password set up. See `BiometricPrompt.Builder#setAllowedAuthenticators(int)`, `Authenticators#DEVICE_CREDENTIAL`, and `BiometricManager#canAuthenticate(int)`.

Constant Value: 14 (0x0000000e)

### BIOMETRIC_ERROR_NO_SPACE

    public static final int BIOMETRIC_ERROR_NO_SPACE

Error state returned for operations like enrollment; the operation cannot be completed because there's not enough storage remaining to complete the operation.

Constant Value: 4 (0x00000004)

### BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED

    public static final int BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED

A security vulnerability has been discovered and the sensor is unavailable until a security update has addressed this issue. This error can be received if for example, authentication was requested with `Authenticators#BIOMETRIC_STRONG`, but the sensor's strength can currently only meet `Authenticators#BIOMETRIC_WEAK`.

Constant Value: 15 (0x0000000f)

### BIOMETRIC_ERROR_TIMEOUT

    public static final int BIOMETRIC_ERROR_TIMEOUT

Error state returned when the current request has been running too long. This is intended to prevent programs from waiting for the biometric sensor indefinitely. The timeout is platform and sensor-specific, but is generally on the order of 30 seconds.

Constant Value: 3 (0x00000003)

### BIOMETRIC_ERROR_UNABLE_TO_PROCESS

    public static final int BIOMETRIC_ERROR_UNABLE_TO_PROCESS

Error state returned when the sensor was unable to process the current image.

Constant Value: 2 (0x00000002)

### BIOMETRIC_ERROR_USER_CANCELED

    public static final int BIOMETRIC_ERROR_USER_CANCELED

The user canceled the operation. Upon receiving this, applications should use alternate authentication (e.g. a password). The application should also provide the means to return to biometric authentication, such as a "use " button.

Constant Value: 10 (0x0000000a)

### BIOMETRIC_ERROR_VENDOR

    public static final int BIOMETRIC_ERROR_VENDOR

OEMs should use this constant if there are conditions that do not fit under any of the other publicly defined constants, and must provide appropriate strings for these errors to the `BiometricPrompt.AuthenticationCallback#onAuthenticationError(int, CharSequence)` callback. OEMs should expect that the error message will be shown to users.

Constant Value: 8 (0x00000008)

## Public methods

### authenticate

    public void authenticate (CancellationSignal cancel,
                    Executor executor,
                    BiometricPrompt.AuthenticationCallback callback)

This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric. It terminates when `BiometricPrompt.AuthenticationCallback.onAuthenticationError(int, java.lang.CharSequence)` is called, when `BiometricPrompt.AuthenticationCallback.onAuthenticationSucceeded(android.hardware.biometrics.BiometricPrompt.AuthenticationResult)` is called, or when the user dismisses the system-provided dialog. This operation can be canceled by using the provided cancel object. The application will receive authentication errors through `AuthenticationCallback`, and button events through the corresponding callback set in `BiometricPrompt.Builder.setNegativeButton(java.lang.CharSequence, java.util.concurrent.Executor, android.content.DialogInterface.OnClickListener)`. It is safe to reuse the `BiometricPrompt` object, and calling `authenticate(android.os.CancellationSignal, java.util.concurrent.Executor, android.hardware.biometrics.BiometricPrompt.AuthenticationCallback)` while an existing authentication attempt is occurring will stop the previous client and start a new authentication. The interrupted client will receive a cancelled notification through `BiometricPrompt.AuthenticationCallback.onAuthenticationError(int, java.lang.CharSequence)`.

Note: Applications generally should not cancel and start authentication in quick succession. For example, to properly handle authentication across configuration changes, it's recommended to use BiometricPrompt in a fragment with setRetainInstance(true). By doing so, the application will not need to cancel/restart authentication during the configuration change.
Requires `Manifest.permission.USE_BIOMETRIC`

Parameters
`cancel` | `CancellationSignal`: An object that can be used to cancel authentication. This value cannot be `null`.
`executor` | `Executor`: An executor to handle callback events. 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()`. To dispatch events through a shared thread pool, you can use `AsyncTask#THREAD_POOL_EXECUTOR`.
`callback` | `BiometricPrompt.AuthenticationCallback`: An object to receive authentication events. This value cannot be `null`.

Throws
`IllegalArgumentException` | If any of the arguments are null.

### authenticate

    public void authenticate (BiometricPrompt.CryptoObject crypto,
                    CancellationSignal cancel,
                    Executor executor,
                    BiometricPrompt.AuthenticationCallback callback)

This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric. It terminates when `BiometricPrompt.AuthenticationCallback.onAuthenticationError(int, java.lang.CharSequence)` is called, when `BiometricPrompt.AuthenticationCallback.onAuthenticationSucceeded(android.hardware.biometrics.BiometricPrompt.AuthenticationResult)`, or when the user dismisses the system-provided dialog, at which point the crypto object becomes invalid. This operation can be canceled by using the provided cancel object. The application will receive authentication errors through `AuthenticationCallback`, and button events through the corresponding callback set in `Builder#setNegativeButton(CharSequence, Executor, DialogInterface.OnClickListener)`. It is safe to reuse the `BiometricPrompt` object, and calling `BiometricPrompt#authenticate(CancellationSignal, Executor, AuthenticationCallback)` while an existing authentication attempt is occurring will stop the previous client and start a new authentication. The interrupted client will receive a cancelled notification through `AuthenticationCallback#onAuthenticationError(int, CharSequence)`.

Note: Applications generally should not cancel and start authentication in quick succession. For example, to properly handle authentication across configuration changes, it's recommended to use BiometricPrompt in a fragment with setRetainInstance(true). By doing so, the application will not need to cancel/restart authentication during the configuration change.

Per the Android CDD, only biometric authenticators that meet or exceed the requirements for Strong are permitted to integrate with Keystore to perform related cryptographic operations. Therefore, it is an error to call this method after explicitly calling `Builder#setAllowedAuthenticators(int)` with any biometric strength other than `Authenticators#BIOMETRIC_STRONG`.
Requires `Manifest.permission.USE_BIOMETRIC`

Parameters
`crypto` | `BiometricPrompt.CryptoObject`: A cryptographic operation to be unlocked after successful authentication. This value cannot be `null`.
`cancel` | `CancellationSignal`: An object that can be used to cancel authentication. This value cannot be `null`.
`executor` | `Executor`: An executor to handle callback events. 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()`. To dispatch events through a shared thread pool, you can use `AsyncTask#THREAD_POOL_EXECUTOR`.
`callback` | `BiometricPrompt.AuthenticationCallback`: An object to receive authentication events. This value cannot be `null`.

Throws
`IllegalArgumentException` | If any argument is null, or if the allowed biometric authenticator strength is explicitly set to `Authenticators#BIOMETRIC_WEAK`. Prior to `Build.VERSION_CODES.R`, this exception is also thrown if `Builder#setDeviceCredentialAllowed(boolean)` was explicitly set to true.

### getAllowedAuthenticators

    public int getAllowedAuthenticators ()

Gets the type(s) of authenticators that may be invoked by the prompt to authenticate the user, as set by `Builder#setAllowedAuthenticators(int)`.

Returns
`int` | A bit field representing the type(s) of authenticators that may be invoked by the prompt (as defined by `Authenticators`), or 0 if this field was not set. This value may be `null`.

### getDescription

    public CharSequence getDescription ()

Gets the description for the prompt, as set by `Builder#setDescription(CharSequence)`.

Returns
`CharSequence` | The description for the prompt, or null if the prompt has no description.

### getNegativeButtonText

    public CharSequence getNegativeButtonText ()

Gets the negative button text for the prompt, as set by `Builder#setNegativeButton(CharSequence, Executor, DialogInterface.OnClickListener)`.

Returns
`CharSequence` | The negative button text for the prompt, or null if no negative button text was set.

### getSubtitle

    public CharSequence getSubtitle ()

Gets the subtitle for the prompt, as set by `Builder#setSubtitle(CharSequence)`.

Returns
`CharSequence` | The subtitle for the prompt, or null if the prompt has no subtitle.

### getTitle

    public CharSequence getTitle ()

Gets the title for the prompt, as set by `Builder#setTitle(CharSequence)`.

Returns
`CharSequence` | The title of the prompt, which is guaranteed to be non-null.

### isConfirmationRequired

    public boolean isConfirmationRequired ()

Determines if explicit user confirmation is required by the prompt, as set by `Builder#setConfirmationRequired(boolean)`.

Returns
`boolean` | true if explicit user confirmation is required, or false otherwise.

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