package tj.fsociety.myfingerprint;

import android.Manifest;
import android.app.KeyguardManager;
import android.content.pm.PackageManager;
import android.hardware.fingerprint.FingerprintManager;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        FingerprintManager fingerprintManager = (FingerprintManager) getSystemService(FINGERPRINT_SERVICE);
        if(allowfingerprint(fingerprintManager)){
            FingerprintHandler fingerprintHandler = new FingerprintHandler(this);
            fingerprintHandler.startAuth(fingerprintManager,null);
        }


    }


    private boolean allowfingerprint(FingerprintManager fingerprintManager){
        KeyguardManager keyguardManager = (KeyguardManager) getSystemService(KEYGUARD_SERVICE);

        if(!fingerprintManager.isHardwareDetected()){
            return false;
        }
        else {
            //здесь ещё была проверка пермищина
            if (!fingerprintManager.hasEnrolledFingerprints()) {
               return false;
            }
            else {
                if (!keyguardManager.isKeyguardSecure()) { //используется ли пароль для разблокировки телефона
                    return false;
                } else {
                    return true;
                }
            }
        }
    }
}

package tj.fsociety.myfingerprint;

import android.Manifest;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.hardware.fingerprint.FingerprintManager;
import android.os.Build;
import android.os.CancellationSignal;
import android.support.annotation.RequiresApi;
import android.support.v4.app.ActivityCompat;
import android.widget.TextView;

/**
 * Created by whit3hawks on 11/16/16.
 */
public class FingerprintHandler extends FingerprintManager.AuthenticationCallback {

    private Context context;

    // Constructor
    public FingerprintHandler(Context mContext) {
        context = mContext;
    }

    @TargetApi(Build.VERSION_CODES.M)
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    public void startAuth(FingerprintManager manager, FingerprintManager.CryptoObject cryptoObject) {
        CancellationSignal cancellationSignal = new CancellationSignal();
        if (ActivityCompat.checkSelfPermission(context, Manifest.permission.USE_FINGERPRINT) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        manager.authenticate(cryptoObject, cancellationSignal, 0, this, null);
    }

    @Override
    public void onAuthenticationError(int errMsgId, CharSequence errString) {
        this.update("Fingerprint Authentication errorn" + errString);
    }

    @Override
    public void onAuthenticationHelp(int helpMsgId, CharSequence helpString) {
        this.update("Fingerprint Authentication helpn" + helpString);
    }

    @Override
    public void onAuthenticationFailed() {
        this.update("Fingerprint Authentication failed.");
    }

    @Override
    public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {
        this.update("Successn" + result);

    }
    private void update(String e){
        TextView textView = (TextView) ((Activity)context).findViewById(R.id.result);
        textView.setText(e);
    }

}