FA GOOGLE LoginWithPhoneAuth-VerifyPhoneActivity.java

package com.arslan6015.firebaseauthusingphoneno;


import android.content.Intent;
import android.nfc.Tag;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.gms.tasks.TaskExecutors;
import com.google.firebase.FirebaseException;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseAuthInvalidCredentialsException;
import com.google.firebase.auth.PhoneAuthCredential;
import com.google.firebase.auth.PhoneAuthProvider;

import java.util.concurrent.TimeUnit;

public class VerifyPhoneActivity extends AppCompatActivity {

        //three objects needed
        //this is the verification id that will be sent to the user
        private String mVerificationId;

        //ditText to input the code
        private EditText editTextCode;

        //fireBase authentication object
        private FirebaseAuth mAuth;
        Button btnSignIn;


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

            //initializing objects
            mAuth = FirebaseAuth.getInstance();
            editTextCode = findViewById(R.id.editTextCode);
            btnSignIn = findViewById(R.id.buttonSignIn);

            //getting mobile number from the previous activity
            //and sending the verification code to the number
            Intent intent = getIntent();
            String mobile = intent.getStringExtra("mobile");
            sendVerificationCode(mobile);


            //if the automatic sms detection did not work, user can also enter the code manually
            //so adding a click listener to the button
            btnSignIn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    String code = editTextCode.getText().toString().trim();
                    if (code.isEmpty() || code.length() < 6) {
                        editTextCode.setError("Enter valid code");
                        editTextCode.requestFocus();
                        return;
                    }

                    //verifying the code entered manually
                    verifyVerificationCode(code);
                }
            });

        }

        //the method is sending verification code
        //the country id is concatenated
        //you can take the country id as user input as well
        private void sendVerificationCode(String mobile) {
            PhoneAuthProvider.getInstance().verifyPhoneNumber(
                    "+" + mobile,                 //phoneNo that is given by user
                    60,                             //Timeout Duration
                    TimeUnit.SECONDS,                   //Unit of Timeout
                    TaskExecutors.MAIN_THREAD,          //Work done on main Thread
                    mCallbacks);                       // OnVerificationStateChangedCallbacks
        }


        //the callback to detect the verification status
        private PhoneAuthProvider.OnVerificationStateChangedCallbacks mCallbacks =
                new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {
            @Override
            public void onVerificationCompleted(PhoneAuthCredential phoneAuthCredential) {

                //Getting the code sent by SMS
                String code = phoneAuthCredential.getSmsCode();

                //sometime the code is not detected automatically
                //in this case the code will be null
                //so user has to manually enter the code
                if (code != null) {
                    editTextCode.setText(code);
                    //verifying the code
                    verifyVerificationCode(code);
                }
            }

            @Override
            public void onVerificationFailed(FirebaseException e) {
                Toast.makeText(VerifyPhoneActivity.this, e.getMessage(), Toast.LENGTH_LONG).show();
                Log.e("TAG",e.getMessage() );
            }

            //when the code is generated then this method will receive the code.
            @Override
            public void onCodeSent(String s, PhoneAuthProvider.ForceResendingToken forceResendingToken) {
//                super.onCodeSent(s, forceResendingToken);

                //storing the verification id that is sent to the user
                mVerificationId = s;
            }
        };

        private void verifyVerificationCode(String code) {
            //creating the credential
            PhoneAuthCredential credential = PhoneAuthProvider.getCredential(mVerificationId, code);
            signInWithPhoneAuthCredential(credential);
        }

        //used for signing the user
        private void signInWithPhoneAuthCredential(PhoneAuthCredential credential) {
            mAuth.signInWithCredential(credential)
                    .addOnCompleteListener(VerifyPhoneActivity.this,
                            new OnCompleteListener<AuthResult>() {

                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {
                            if (task.isSuccessful()) {
                                //verification successful we will start the profile activity
                                Intent intent = new Intent(VerifyPhoneActivity.this, ProfileActivity.class);
                                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
                                startActivity(intent);

                            } else {

                                //verification unsuccessful.. display an error message

                                String message = "Somthing is wrong, we will fix it soon...";

                                if (task.getException() instanceof FirebaseAuthInvalidCredentialsException) {
                                    message = "Invalid code entered...";
                                }
                                Toast.makeText(VerifyPhoneActivity.this,message,Toast.LENGTH_SHORT).show();
                            }
                        }
                    });
        }

}