gistfile1.txt

let KeyStore = java.security.KeyStore
let Cipher = javax.crypto.Cipher
let KeyGenerator = javax.crypto.KeyGenerator
let KeyProperties = android.security.keystore.KeyProperties
let KeyGenParameterSpec = android.security.keystore.KeyGenParameterSpec
let FingerprintManager = android.hardware.fingerprint.FingerprintManager

export class TestClass {
    private keyguardManager = utils.ad.getApplicationContext().getSystemService("keyguard")
    private fingerprintManager = utils.ad.getApplicationContext().getSystemService("fingerprint")
    private REQUEST_CODE_CONFIRM_DEVICE_CREDENTIALS = 1001
    private KEY_NAME = 'fingerprintauth'
    
    startFingerprintMagic() {
              let cancellationSignal = new android.os.CancellationSignal()

        let cipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/" +
            KeyProperties.BLOCK_MODE_CBC + "/" + KeyProperties.ENCRYPTION_PADDING_PKCS7)

        let cryptoObject = FingerprintManager.CryptoObject(cipher)

        let callbackClass = FingerprintManager.AuthenticationCallback.extend({
            onAuthenticationError: function (args) {
                console.log("error")
            },
            onAuthenticationHelp: function (args) {
                console.log("help?")
            },
            onAuthenticationSucceeded: function (args) {
                console.log("success")
            },
            onAuthenticationFailed: function () {
                console.log("failed")
            }
        })

        let callbackInstance = new callbackClass()
        //the following line dies with "Trying to link invalid 'this' to a Java object"
        this.fingerprintManager.authenticate(cryptoObject, cancellationSignal, 0, callbackInstance, null)
    }
}