public class ManejoDeHuellas extends FingerprintManager.AuthenticationCallback {
    public void empezarAutenticacionHuella(FingerprintManager manager, FingerprintManager.CryptoObject cryptoObject){
        cancellationSignal = new CancellationSignal(); //para poder cancelar una operación en progreso.
        //Verificar otra vez si es que se tienen permisos de usaar huella dactilar
        ...
        //Aqui inicia la autenticación.
        manager.authenticate(cryptoObject,cancellationSignal,0,this,null);
    }
    @Override
    public void onAuthenticationError(int errMsgId, CharSequence errString){
        Toast.makeText(appContext,"Error en la Autenticacion\n"+errString,Toast.LENGTH_LONG).show();
    }
    @Override
    public void onAuthenticationHelp(int helpMsgId,CharSequence helpString){
        Toast.makeText(appContext,"Ayuda en la autenticacion\n"+helpString,Toast.LENGTH_LONG).show();
    }
    @Override
    public void onAuthenticationFailed(){
        Toast.makeText(appContext,"Fallo en la autenticación.", Toast.LENGTH_LONG).show();
    }
    @Override
    public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result){
    Toast.makeText(appContext, "Autenticación satisfactoria :D",Toast.LENGTH_LONG).show();
    }