Attempt to invoke virtual method on a null object reference...///

Question

I am new to java and today I received this error: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.common.SignInButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference I thought I would have a reference with the findviewbyid command but somehow it is not working. Could someone help me?

package com.~;

import androidx.activity.result.ActivityResult;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContract;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.auth.GoogleAuthProvider;

public class MainActivity extends AppCompatActivity {

    //Google Sign In
    private SignInButton googleSignIn;

    private GoogleSignInClient googleSignInClient;

    private FirebaseAuth firebaseAuth;

    private static final String TAG= "Google Sign In Tag";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        googleSignIn = findViewById(R.id.googleSignInButton1);

        //configure Google Sign In
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();

        googleSignInClient = GoogleSignIn.getClient(this, gso);

        //int Firebase Auth
        firebaseAuth = FirebaseAuth.getInstance();

        //Google Sign In Button
        googleSignIn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //begin Google Sign In
                Log.d(TAG,"onClick: begin Google Sign In");
                Intent intent = googleSignInClient.getSignInIntent();

                resultLauncher.launch(new Intent(googleSignInClient.getSignInIntent()));

            }
        });
    }

    ActivityResultLauncher<Intent> resultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), new ActivityResultCallback<ActivityResult>() {
        @Override
        public void onActivityResult(ActivityResult result) {

            if(result.getResultCode() == Activity.RESULT_OK){
                Intent intent = result.getData();

                Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(intent);
                try {
                    // Google Sign In was successful, authenticate with Firebase
                    GoogleSignInAccount account = task.getResult(ApiException.class);
                    Log.d(TAG, "firebaseAuthWithGoogle:" + account.getId());
                    firebaseAuthWithGoogle(account.getIdToken());
                } catch (ApiException e) {
                    // Google Sign In failed, update UI appropriately
                    Log.w(TAG, "Google sign in failed", e);
                }
            }

        }
    });

    private void firebaseAuthWithGoogle(String idToken) {
        Log.d(TAG,"firebaseAuthWithGoogleAccount: begin firebase auth with google account");
        AuthCredential credential = GoogleAuthProvider.getCredential(idToken, null);

        firebaseAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            // Sign in success, update UI with the signed-in user's information
                            Log.d(TAG, "signInWithCredential:success");

                            //get logged in user
                            FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();

                            //get user info
                            String uid = firebaseUser.getUid();
                            String email = firebaseUser.getEmail();

                            //check if user is new or existing

                            //start Profile Activity
                            startActivity(new Intent(MainActivity.this, Timer.class));
                            finish();

                            //updateUI(user);
                        } else {
                            // If sign in fails, display a message to the user.
                            Log.w(TAG, "signInWithCredential:failure", task.getException());
                            //updateUI(null);
                        }
                    }
                });
    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="20dp"
    tools:context=".MainActivity">

    <layout></layout>

    <ImageView
        android:id="@+id/googleLogo"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:layout_marginTop="20dp"
        android:layout_centerHorizontal="true"
       />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/googleLogo"
        android:text="Welcome"
        style="@style/TextAppearance.AppCompat.Body1"/>

    <com.google.android.gms.common.SignInButton
        android:id="@+id/googleSignInButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"/>

</RelativeLayout>