Question: I'm asked to show certain UI elements depending on the presence of biometric hardware. For Android 23-27 I use `FingerprintManager#isHardwareDetected()` and `FingerprintManager#hasEnrolledFingerprints()`. Both of which are deprecated in Android 28.

I understand that I can get this information by using `BiometricPrompt#authenticate(...)` and receiving either `BiometricPrompt#BIOMETRIC_ERROR_HW_NOT_PRESENT` or `BiometricPrompt#BIOMETRIC_ERROR_NO_BIOMETRICS` in the `BiometricPrompt.AuthenticationCallback#onAuthenticationError(int errorCode, ...)` method. But this would lead to the `BiometricPrompt` being shown on supporting devices, which is undesirable. Using the `CancellationSignal` doesn't seem to be a solution either, since I wouldn't know when to cancel the prompt.

Is there any way to detect biometric hardware presence and user enrolment?

Answer: 
In my biometrics, I used these and a few more checks to make sure that the device was capable and the fingerprint was enabled. In Kotlin I created an Object class and called it utilities.

```
object BiometricUtilities {
    fun isBiometricPromptEnabled(): Boolean {
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.P
    }
    fun isSdkVersionSupported(): Boolean {
    return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M
    }
    fun isHardwareSupported(context: Context): Boolean {
        val fingerprintManager = FingerprintManagerCompat.from(context)
        return fingerprintManager.isHardwareDetected
    }
    fun isFingerprintAvailable(context: Context): Boolean {
        val fingerprintManager = FingerprintManagerCompat.from(context)
        return fingerprintManager.hasEnrolledFingerprints()
    }
}

```

Then in my bioManager class, I placed the conditional statements under a function called authenticate that implements BiometricCallback

```
fun authenticate(biometricCallback: BiometricCallback) {

    if (!BiometricUtilities.isHardwareSupported(context)) {
        biometricCallback.onBiometricAuthenticationNotSupported()
        return
    }

    if (!BiometricUtilities.isFingerprintAvailable(context)) {
        val intent = Intent(Settings.ACTION_SECURITY_SETTINGS)
           biometricCallback.onBiometricAuthenticationNotAvailable()
        return
    }

    displayBiometricDialog(biometricCallback)
}

```

This way you can check for availability of hardware and presence of fingerprint on the device and let the OS help you to display a prompt or not
The method - checks that the user has biometric authentication permission enabled for the app before using the package manager to verify that fingerprint authentication is available on the device. And even it will check if the user is enrolled or not. 

implementation 'androidx.biometric:biometric:1.0.0-alpha03'

```
private Boolean checkBiometricSupport() {

    KeyguardManager keyguardManager =
            (KeyguardManager) getSystemService(KEYGUARD_SERVICE);

    PackageManager packageManager = this.getPackageManager();

    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
        notifyUser("This Android version does not support fingerprint authentication.");
        return false;
    }

    if(!packageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT))
    {
        notifyUser("Fingerprint Sensor not supported");
        return false;
    }

    if (!keyguardManager.isKeyguardSecure()) {
        notifyUser("Lock screen security not enabled in Settings");

        return false;
    }

    if (ActivityCompat.checkSelfPermission(this,
            Manifest.permission.USE_BIOMETRIC) !=
            PackageManager.PERMISSION_GRANTED) {
        notifyUser("Fingerprint authentication permission not enabled");

        return false;
    }

    return true;
}

```