java android firebase firebase-authentication one-time-password

I'm Not recieving an Otp from firebase in the Phone authentication system

I have basically created 2 Xmls. one where the user enters the phone number and then on pressing a button it goes to the OTP verification screen. But the issue here is that I am not receiving any OTP from Firebase, but after 5 sec I get a toast message that the verification failed. How could it fail if I haven't even got the message. I also tried putting another number so that I can enter the code manually. But Firebase isn't sending me the OTP.

BASIC IMPLEMENTATION --- click Forgot Password -> Ask for Mobile Num ->Verify Otp ->Reset Password->Login Page

P.S I have enabled the phone authentication in Firebase.

OtpActivity.java

public class VerifyOtp extends AppCompatActivity {

    public String NumberEnteredByUser,verificationCodeBySystem;
    Button VerifyButton;
    PinView phoneEnteredByUser;
    FirebaseAuth auth;
    PhoneAuthProvider.OnVerificationStateChangedCallbacks mCallback;



    

    @RequiresApi(api = Build.VERSION_CODES.N)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_verify_otp);
        getSupportActionBar().hide();

        Intent intent =getIntent();
        NumberEnteredByUser = intent.getStringExtra("phoneNo");



        VerifyButton = findViewById(R.id.btnVerify);
        phoneEnteredByUser = findViewById(R.id.EnterCode);
        auth = FirebaseAuth.getInstance();

        send_code_to_user(NumberEnteredByUser);




        VerifyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                checkcode();
            }
        });

    }


    private void checkcode() {
        String userEnteredOtp = phoneEnteredByUser.getText().toString();
        if(userEnteredOtp.isEmpty() || userEnteredOtp.length()<6){
            Toast.makeText(this, "Wrong Otp!", Toast.LENGTH_SHORT).show();
            return;
        }
        finishEverything(userEnteredOtp);
    }

    private void finishEverything(String code) {
        phoneEnteredByUser.setText(code);
        PhoneAuthCredential credential = PhoneAuthProvider.getCredential(verificationCodeBySystem,code);
        sign_in(credential);
    }

    private void sign_in(PhoneAuthCredential credential) {
        FirebaseAuth auth = FirebaseAuth.getInstance();
        auth.signInWithCredential(credential).addOnCompleteListener(VerifyOtp.this, new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                if(task.isSuccessful())
                {
                    Toast.makeText(VerifyOtp.this, "UserSignedInSuccessfully", Toast.LENGTH_SHORT).show();
                    startActivity(new Intent(getApplicationContext(),ResetPassword.class));
                }
                else {
                    Toast.makeText(VerifyOtp.this,task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                }
            }
        });

    }

    private void send_code_to_user(String NumberEnteredByUser ) {
        PhoneAuthOptions options =
                PhoneAuthOptions.newBuilder(auth)
                        .setPhoneNumber(NumberEnteredByUser)       // Phone number to verify
                        .setTimeout(60L, TimeUnit.SECONDS) // Timeout and unit
                        .setActivity(this)                 // Activity (for callback binding)
                        .setCallbacks(new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {

                            @Override
                            public void onVerificationCompleted(PhoneAuthCredential phoneAuthCredential) {
                                Toast.makeText(VerifyOtp.this, "Verification Completed", Toast.LENGTH_SHORT).show();
                                String code = phoneAuthCredential.getSmsCode();
                                if (code != null) {
                                    finishEverything(code);
                                }
                            }

                            @Override
                            public void onVerificationFailed(FirebaseException e) {
                                Toast.makeText(VerifyOtp.this, "Verification Failed", Toast.LENGTH_SHORT).show();
                            }

                            @Override
                            public void onCodeSent(String s, PhoneAuthProvider.ForceResendingToken forceResendingToken) {
                                super.onCodeSent(s, forceResendingToken);
                                verificationCodeBySystem = s;
                                Toast.makeText(VerifyOtp.this, "Code sent", Toast.LENGTH_SHORT).show();
                            }
                        })          // OnVerificationStateChangedCallbacks
                        .build();
        PhoneAuthProvider.verifyPhoneNumber(options);

    }
}

Build Gradle Project

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.1.2"
        classpath 'com.google.gms:google-services:4.3.8'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Build Gradle App

plugins {
    id 'com.android.application'
    id 'com.google.gms.google-services'


}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.mitadt.newui"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"
        multiDexEnabled true

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation platform('com.google.firebase:firebase-bom:28.0.1')
    implementation 'com.google.firebase:firebase-analytics'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'androidx.navigation:navigation-fragment:2.2.2'
    implementation 'androidx.navigation:navigation-ui:2.2.2'
    implementation 'com.google.firebase:firebase-firestore:23.0.0'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
    implementation 'com.google.firebase:firebase-database:19.7.0'
    implementation 'com.google.firebase:firebase-auth:19.3.2'
    implementation 'com.android.support:multidex:1.0.3'
    //OTP VIEW DEPENDENCY
    implementation 'com.chaos.view:pinview:1.4.3'
}

Kindly help me out. Thankyou!!!

Solution

The verification failed because you didn't enable app verification. To do so, you can follow these steps:

Goto Google Cloud Console, Select your project and Enable Android Device Verification. Here is the direct link: https://console.cloud.google.com/apis/library/androidcheck.googleapis.com
In Android studio, go to top right corner bar, and press "Gradle". Then Expand (your project name) > app > Tasks > android, and double click on signingReport. You will find SHA1 and SHA-256 in the run window like below:
Goto your firebase console, and open tha app. Goto Project Settings. Scroll down, you'll find Add Fingerprint where you will need to insert the both SHA1 and SHA-256 key. After inserting, you will need to download the updated google-services.json. Replace the old google-services.json in the android studio project with the new one.
Now, add the browser dependency in app-level grade because the app will need to open captcha verification page from the browser:
```
 implementation 'androidx.browser:browser:1.3.0' 
```
Then, in Android Studio top menu Build > Clean Project and Build > Rebuild Project

Now, you're good to go.

Note: Your app may show a captcha verification web page