A class which extends FingerprintManager.AuthenticationCallback.

AuthCallbacks.java

class AuthCallbacks extends FingerprintManager.AuthenticationCallback {
  
        @Override
        public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {
            // Called when a fingerprint is recognized.
          
            // The AuthenticationResult contains the CryptoObject which 
            // has been passed to the authenticate() method.
            Cipher cipher = result.getCryptoObject().getCipher();
            // Go on and use the 'unlocked' Cipher object...
        }
  
        @Override
        public void onAuthenticationError(int errorCode, CharSequence errString) {
            // Called when an unrecoverable error has been encountered and
            // the operation is complete. No further callbacks will be
            // made on this object.
        }

        @Override
        public void onAuthenticationFailed() {
            // Called when a fingerprint is valid but not recognized.
        }

        @Override
        public void onAuthenticationHelp(int helpCode, CharSequence helpString) {
            // Called when a recoverable error has been encountered 
            // during authentication. The help string is provided to 
            // give the user guidance for what went wrong, such as
            // "Sensor dirty, please clean it."
        }
    }