How to Add Fingerprint Authentication in Your Android App? - GeeksforGeeks

16 Feb, 2021
Now a day, we have seen that most of our Android phone contains fingerprint authentication. And we can implement that fingerprint authentication in our app so to secure our app as much as we can. In this article, we will take a look at the implementation of fingerprint authentication.
We will be building a simple application in which we will be displaying an image of a fingerprint and a login button. After clicking on the login button we will apply our fingerprint. And if that same fingerprint is added into the Security setting then we will get login success. A sample video is given below to get an idea about what we are going to do in this article. Note that we are going to implement this project using the Java language. 
Step 1: Create a New Project
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Java as the programming language.
Step 2: Add dependency and JitPack Repository
Navigate to the Gradle Scripts > build.gradle(Module:app) and add the below dependency in the dependencies section.   
implementation ‘androidx.biometric:biometric:1.0.1’
Add the JitPack repository to your build file. Add it to your root build.gradle at the end of repositories inside the allprojects{ } section.
allprojects {
 repositories {
   ...
   maven { url “https://jitpack.io” }
     }
}
After adding this dependency sync your project and now we will move towards its implementation.  
Step 3: Working with the AndroidManifst.xml file
Add the following line inside your AndroidManifst.xml file.
<uses-permission android:name=”android.permission.USE_BIOMETRIC”/>
Step 4: Working with the activity_main.xml file
Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. 
XML
<?xml version="1.0" encoding="utf-8"?><LinearLayout     xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="@drawable/background"    android:gravity="center"    android:orientation="vertical"    tools:context=".MainActivity">      <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="GFG | First App"        android:textColor="#fafafa"        android:textSize="30dp" />      <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Use your fingerprint to login"        android:textColor="#fafafa"        android:textSize="18sp" />      <ImageView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginVertical="20dp"        android:src="@drawable/ic_fingerprint_black_24dp" />      <TextView        android:id="@+id/msgtext"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text=""        android:textSize="18sp" />      <Button        android:id="@+id/login"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginVertical="20dp"        android:background="#fafafa"        android:text="Login" />  </LinearLayout>
Create a new Drawable Resource File and name the file as the background. Below is the code for the background.xml file.
XML
<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android">    <gradient        android:angle="-90"        android:endColor="#fff"        android:startColor="#29DA2E" /></shape>
Step 4: Working with the MainActivity.java file
Go to the MainActivity.java file and refer to the following code. Below is the code for the MainActivity.java file. Comments are added inside the code to understand the code in more detail.
Java
import android.graphics.Color;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;import android.widget.Toast;  import androidx.annotation.NonNull;import androidx.appcompat.app.AppCompatActivity;import androidx.biometric.BiometricManager;import androidx.biometric.BiometricPrompt;import androidx.core.content.ContextCompat;  import java.util.concurrent.Executor;  public class MainActivity extends AppCompatActivity {      @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);          // Initialising msgtext and loginbutton        TextView msgtex = findViewById(R.id.msgtext);        final Button loginbutton = findViewById(R.id.login);          // creating a variable for our BiometricManager        // and lets check if our user can use biometric sensor or not        BiometricManager biometricManager = androidx.biometric.BiometricManager.from(this);        switch (biometricManager.canAuthenticate()) {                          // this means we can use biometric sensor            case BiometricManager.BIOMETRIC_SUCCESS:                msgtex.setText("You can use the fingerprint sensor to login");                msgtex.setTextColor(Color.parseColor("#fafafa"));                break;                              // this means that the device doesn't have fingerprint sensor            case BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE:                msgtex.setText("This device doesnot have a fingerprint sensor");                loginbutton.setVisibility(View.GONE);                break;              // this means that biometric sensor is not available            case BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE:                msgtex.setText("The biometric sensor is currently unavailable");                loginbutton.setVisibility(View.GONE);                break;                              // this means that the device doesn't contain your fingerprint            case BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED:                msgtex.setText("Your device doesn't have fingerprint saved,please check your security settings");                loginbutton.setVisibility(View.GONE);                break;        }        // creating a variable for our Executor        Executor executor = ContextCompat.getMainExecutor(this);        // this will give us result of AUTHENTICATION        final BiometricPrompt biometricPrompt = new BiometricPrompt(MainActivity.this, executor, new BiometricPrompt.AuthenticationCallback() {            @Override            public void onAuthenticationError(int errorCode, @NonNull CharSequence errString) {                super.onAuthenticationError(errorCode, errString);            }              // THIS METHOD IS CALLED WHEN AUTHENTICATION IS SUCCESS            @Override            public void onAuthenticationSucceeded(@NonNull BiometricPrompt.AuthenticationResult result) {                super.onAuthenticationSucceeded(result);                Toast.makeText(getApplicationContext(), "Login Success", Toast.LENGTH_SHORT).show();                loginbutton.setText("Login Successful");            }            @Override            public void onAuthenticationFailed() {                super.onAuthenticationFailed();            }        });        // creating a variable for our promptInfo        // BIOMETRIC DIALOG        final BiometricPrompt.PromptInfo promptInfo = new BiometricPrompt.PromptInfo.Builder().setTitle("GFG")                .setDescription("Use your fingerprint to login ").setNegativeButtonText("Cancel").build();        loginbutton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                biometricPrompt.authenticate(promptInfo);              }        });    }}
GitHub link: https://github.com/Anni1123/FingerprintAuthentication
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