Android Studio - App wird wiederholt beendet

Hallo erstmal,
nachdem ich den folgenden Codeausschnitt in meinen gesamten Code eingefügt habe und dann die app per adb/usb an meinem handy ausprobiere wird sie wiederholt beendet. Ich weiß einfach nicht weiter... PS: Ich programmieren einen Login und Registrierung Screen für eine App von mir.

Hier der eingefügte Code(die App beendet sich nur wenn ich ihn eingefügt habe; es werden keine Fehler ausgegeben):
mLoginBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String email = mEmail.getText().toString().trim();
String password = mPassword.getText().toString().trim();

            if(TextUtils.isEmpty(email)){
                mEmail.setError("Email is Required.");
                return;
            }

            if(TextUtils.isEmpty(password)){
                mPassword.setError("Password is Required.");
                return;
            }

            if(password.length() < 6){
                mPassword.setError("Password Must Be >= 6 Characters");
                return;
            }

            // authenticate the user
            fAuth.signInWithEmailAndPassword(email,password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if(task.isSuccessful()){
                        Toast.makeText(Login.this, "Logged in Successfully.", Toast.LENGTH_SHORT).show();
                        startActivity(new Intent(getApplicationContext(), Home.class));
                    }else{
                        Toast.makeText(Login.this, "Error ! " + task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                    }
                }
            });

        }
    });
}

2020-04-30 20:35:14.486 26273-26273/com.example.socialnetwork E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.socialnetwork, PID: 26273
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.socialnetwork/com.example.socialnetwork.Login}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3387)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3526)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2122)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7695)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.socialnetwork.Login.onCreate(Login.java:37)
at android.app.Activity.performCreate(Activity.java:7820)
at android.app.Activity.performCreate(Activity.java:7809)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1318)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3362)

Wie kann ich das ändern? Ich bin anfänger sorry xd

funktioniert nicht also es hat nichts gebracht
public class Login extends AppCompatActivity {
EditText mEmail,mPassword;
Button mLoginBtn = findViewById(R.id.btnLogin);
TextView mCreateBtn;
FirebaseAuth fAuth;

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

    mEmail       = findViewById(R.id.Email);
    mPassword    = findViewById(R.id.password);
    fAuth        = FirebaseAuth.getInstance();
    mLoginBtn    = findViewById(R.id.loginBtn);
    mCreateBtn   = findViewById(R.id.createText);

package com.example.socialnetwork;

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

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

public class Login extends AppCompatActivity {
EditText mEmail,mPassword;
Button mLoginBtn;
TextView mCreateBtn;
FirebaseAuth fAuth;

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

    mEmail       = findViewById(R.id.Email);
    mPassword    = findViewById(R.id.password);
    fAuth        = FirebaseAuth.getInstance();
    mLoginBtn    = findViewById(R.id.loginBtn);
    mCreateBtn   = findViewById(R.id.createText);

    mLoginBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String email = mEmail.getText().toString().trim();
            String password = mPassword.getText().toString().trim();

            if(TextUtils.isEmpty(email)){
                mEmail.setError("Email is Required.");
                return;
            }

            if(TextUtils.isEmpty(password)){
                mPassword.setError("Password is Required.");
                return;
            }

            if(password.length() < 6){
                mPassword.setError("Password Must Be >= 6 Characters");
                return;
            }

            // authenticate the user
            fAuth.signInWithEmailAndPassword(email,password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {

weiter kann ich nichjt posten sagt androdin pitt

ja sind vorhanden

also die app startet jetzt das problem ist wenn ich auf den login button drücke dann wird die app beendet