Setting up a text view as a clickable button

I am developing a simple application which allows users to login using a username and password, I am trying to set up a "register" link in the form of a TextView which will take the user to the register page of the app. I can't find any error in my coding or logic but when I run the app and click the register link, the app just shuts down.

Here is my MainActivity code -

package com.example.squashsademo;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    EditText mTextUsername;
    EditText mTextPassword;
    Button mButtonLogin;
    TextView mTextViewRegister;


//    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        mTextUsername = (EditText)findViewById(R.id.edittext_username);
        mTextPassword = (EditText)findViewById(R.id.edittext_password);
        mButtonLogin = (Button)findViewById(R.id.button_login);
        mTextViewRegister = (TextView)findViewById(R.id.textview_register);
        mTextViewRegister.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                Intent registerIntent = new Intent(MainActivity.this,RegisterActivity.class);
                startActivity(registerIntent);
            }
        });
            }
        }

Here is the RegisterActivity I am trying to get to -

package com.example.squashsademo;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class RegisterActivity extends AppCompatActivity {
    EditText mTextUsername;
    EditText mTextPassword;
    EditText mTextCnfPassword;
    Button mButtonRegister;
    TextView mTextViewLogin;

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

        mTextUsername = (EditText)findViewById(R.id.edittext_username);
        mTextPassword = (EditText)findViewById(R.id.edittext_password);
        mTextCnfPassword = (EditText) findViewById(R.id.edittext_cnf_password);
        mButtonRegister = (Button)findViewById(R.id.button_login);
        mTextViewLogin = (TextView)findViewById(R.id.textview_register);
        mTextViewLogin.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                Intent LoginIntent = new Intent(RegisterActivity.this,MainActivity.class);
                startActivity(LoginIntent);
            }
        });
    }
}

and here is my AndroidManifest -

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.squashsademo">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.SquashSADemo">
        <activity android:name=".RegisterActivity"></activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Can anyone help see why this is not working because from my understanding it should be
Thank you

EDIT - here are the layout files aswell

MainActivity -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    tools:context=".MainActivity"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    android:background="@drawable/background">

    <ImageView
        android:layout_width="299dp"
        android:layout_height="80dp"
        app:srcCompat="@drawable/logo" />

    <EditText
        android:id="@+id/edittext_username"
        android:layout_width="356dp"
        android:layout_height="57dp"
        android:layout_marginTop="160dp"
        android:background="@drawable/custom_input"
        android:drawableLeft="@drawable/username"
        android:drawablePadding="12dp"
        android:hint="@string/username"
        android:textColorHint="@color/white"/>

    <EditText
        android:id="@+id/edittext_password"
        android:layout_width="356dp"
        android:layout_height="57dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/custom_input"
        android:drawableLeft="@drawable/password"
        android:drawablePadding="12dp"
        android:hint="@string/password"
        android:textColorHint="@color/white"/>

    <Button
        android:id="@+id/button_login"
        android:layout_width="wrap_content"
        android:layout_height="40dp"
        android:layout_marginTop="20dp"
        android:text="@string/login"/>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:textColor="#ffffff"
            android:text="@string/not_registered"/>

        <TextView
            android:id="@+id/textview_register"
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:paddingLeft="10dp"
            android:textStyle="bold"
            android:textColor="#ffffff"
            android:text="@string/register"/>

    </LinearLayout>





</LinearLayout>

RegisterActivity -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:background="@drawable/background"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    tools:context=".RegisterActivity">

    <ImageView
        android:layout_width="298dp"
        android:layout_height="80dp"
        app:srcCompat="@drawable/logo" />

    <EditText
        android:id="@+id/edittext_username"
        android:layout_width="356dp"
        android:layout_height="57dp"
        android:layout_marginTop="160dp"
        android:background="@drawable/custom_input"
        android:drawableLeft="@drawable/username"
        android:drawablePadding="12dp"
        android:hint="@string/username"
        android:textColorHint="@color/white"/>

    <EditText
        android:id="@+id/edittext_password"
        android:layout_width="356dp"
        android:layout_height="57dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/custom_input"
        android:drawableLeft="@drawable/password"
        android:drawablePadding="12dp"
        android:hint="@string/password"
        android:textColorHint="@color/white" />

    <EditText
        android:id="@+id/edittext_cnf_password"
        android:drawablePadding="12dp"
        android:background="@drawable/custom_input"
        android:layout_width="356dp"
        android:layout_height="57dp"
        android:layout_marginTop="20dp"
        android:drawableLeft="@drawable/password"
        android:hint="@string/confirm_password"
        android:textColorHint="@color/white"/>

    <Button
        android:id="@+id/button_register"
        android:layout_width="wrap_content"
        android:layout_height="40dp"
        android:layout_marginTop="20dp"
        android:text="@string/register"/>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:textColor="#ffffff"
            android:text="@string/already_registered"/>

        <TextView
            android:id="@+id/textview_login"
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:paddingLeft="10dp"
            android:textStyle="bold"
            android:textColor="#ffffff"
            android:textSize="16dp"
            android:text="@string/login"/>

    </LinearLayout>


</LinearLayout>

here are the log files aswell -

2020-10-21 20:56:22.881 11328-11328/? E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.squashsademo, PID: 11328
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.squashsademo/com.example.squashsademo.RegisterActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3654)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3806)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2267)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:8167)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:496)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1100)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.example.squashsademo.RegisterActivity.onCreate(RegisterActivity.java:28)
        at android.app.Activity.performCreate(Activity.java:7963)
        at android.app.Activity.performCreate(Activity.java:7952)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3629)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3806) 
        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$H.handleMessage(ActivityThread.java:2267) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:237) 
        at android.app.ActivityThread.main(ActivityThread.java:8167) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:496) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1100) 

Below line of code is throwing NullPoinerException

mTextViewLogin = (TextView)findViewById(R.id.textview_register);

in the register activity layout, there is no id as textview_register that's why you are getting the issue

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference

possible fix using below line

mTextViewLogin = (TextView)findViewById(R.id.textview_login);

instead of

mTextViewLogin = (TextView)findViewById(R.id.textview_register);

you can see you are trying to link XML view to java with an invalid id