问Android Studio kotlin应用程序“继续停止”错误

EN

package com.example.absolutelydumb

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.InputType
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import kotlinx.android.synthetic.main.activity_main.*

//sets var to some random number and asks for a guess, giving feedback on proximity to answer
class MainActivity : AppCompatActivity() {
    private val startButton: Button = findViewById(R.id.startButton)
    private val submitButton: Button = findViewById(R.id.submit)
    private val instructionsText: TextView = findViewById(R.id.instructionView)
    private val response: EditText = findViewById(R.id.answerInput)


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val startText: String = getString(R.string.startText)
        startButton.text = startText

        //TODO("Add autofillHints")

        startButton.setOnClickListener {
            numberGuess()
        }
        //TODO("Set text back to start after guessing is done")
    }
    fun numberGuess() {
        response.inputType = InputType.TYPE_CLASS_NUMBER
        val clickText: String = getString(R.string.clickText)
        startButton.text = clickText
        //TODO("Add autofillHints")
        instructionsText.text = getString(R.string.instructions)
        val randomNumber: Int = rand(0,10)
        submitButton.setOnClickListener {
            val responseText = Integer.parseInt(answerInput.text.toString())
            if(responseText == randomNumber) {
                instructionsText.text = getString(R.string.correctGuess)
            } else {
                instructionsText.text = getString(R.string.badGuess)
            }
        }

    }
    fun rand(start: Int, end: Int): Int {
        //require(start <= end) { "Illegal Argument" }
        return (start..end).random()
    }
}

07/09 19:58:05: Launching 'app' on phone1.
Install successfully finished in 1 s 266 ms.
$ adb shell am start -n "com.example.absolutelydumb/com.example.absolutelydumb.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Connected to process 5935 on device 'phone1 [emulator-5554]'.
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.absolutelydumb, PID: 5935
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.absolutelydumb/com.example.absolutelydumb.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2843)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
        at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:159)
        at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:157)
        at android.content.Context.obtainStyledAttributes(Context.java:675)
        at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:692)
        at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
        at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:479)
        at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:214)
        at com.example.absolutelydumb.MainActivity.<init>(MainActivity.kt:13)
        at java.lang.Class.newInstance(Native Method)
        at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:69)
        at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:45)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1215)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2831)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)