Fatal Exception null object reference in Android studio - android-studio

Question

I'm working on an app where on a button click, the app will take the user from main activity to new activity. I've got everything coded and I am just trying to link up the activities now but I'm getting fatal errors which I cannot really understand. The app crashes when I try the button in testing and in Debug I get the error which I have pasted below. I've also pasted my code for the button and the XML for main activity. Can anybody help me make some sense of this error please? Also, if I have left any information out please let me know. Thanks.
Note: In the code for my button, the button I get the error with is the newactivity one.
Error:
2021-06-15 21:15:39.489 8340-8340/com.project.playshow E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.project.playshow, PID: 8340
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.project.playshow/com.fproject.playshow.newactivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.project.playshow.newctivity.onCreate(newactivity.kt:97)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 
at android.os.Handler.dispatchMessage(Handler.java:106) 
at android.os.Looper.loop(Looper.java:223) 
at android.app.ActivityThread.main(ActivityThread.java:7656) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 
Code used in MainActivity for Button (newactivityopen is the one I'm having issues with)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
var dialogbutton = findViewById<Button>(R.id.dialogbtn)
dialogbutton.setOnClickListener{
openDialogue()
}
var newactivityopen = findViewById<Button>(R.id.button_newactivity)
newactivityopen.setOnClickListener{
var intent = Intent(this, newactivity::class.java)
startActivity(intent);
}
}
XML File
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/dialogbtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/app_name"/>
<Button
android:id="#+id/button_newactivity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="569dp"
android:text="NewActivity"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

I´m not familiar with Kotlin (only java), but is it possible that you have setted the onClickListener to a Button, which doesn´t exist?
Try replacing these code snippets:
sdkButton.setOnClickListener with dialogbutton.setOnClickListener
button_newactivity.setOnClickListener with newactivityopen.setOnClickListener