java.lang.NullPointerException: findViewById(R.id.contactsList) must not be null

Question

I am not able to move from one activity to another.

Here is the error:

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.mobiledevelopment, PID: 7613 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mobiledevelopment/com.example.mobiledevelopment.SearchContactActivity}: java.lang.NullPointerException: findViewById(R.id.contactsList) must not be null 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: findViewById(R.id.contactsList) must not be null at com.example.mobiledevelopment.SearchContactActivity.readContact(SearchContactActivity.kt:56) at com.example.mobiledevelopment.SearchContactActivity.onCreate(SearchContactActivity.kt:30) 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)

Here is my SettingsActivity code:

    class SettingsActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_settings_activity)
        val searchBtn : Button = findViewById(R.id.searchButton)
        searchBtn.setOnClickListener {
            val intent = Intent(this@SettingsActivity, SearchContactActivity::class.java)
            startActivity(intent)
        }
    }
}

Here is my SearchContactActivity code:

class SearchContactActivity : AppCompatActivity() {
    // an array of strings that represents the contact
    var cols = listOf(                                              //<String>
        ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME,
        ContactsContract.CommonDataKinds.Phone.NUMBER,
        ContactsContract.CommonDataKinds.Phone._ID
    ).toTypedArray()

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

// asking for permission to read contacts
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, Array(1) { Manifest.permission.READ_CONTACTS }, 111)
        } else
            readContact()    // row 30
    }
    // result of permission asking
    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        if (requestCode == 111 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
            readContact()    
    }

    private fun readContact() {

        var from = listOf<String>(
            ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME,
            ContactsContract.CommonDataKinds.Phone.NUMBER).toTypedArray()

        var to = intArrayOf(android.R.id.text1, android.R.id.text2)

        var rs = contentResolver.query(
            ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
            cols, null, null,
            ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME)

        var adapter = SimpleCursorAdapter(this, android.R.layout.simple_list_item_2,
            rs,from,to,0)


        val contactsList : ListView = findViewById(R.id.contactsList)    //row 56
        contactsList.adapter = adapter

        val searchView : SearchView = findViewById(R.id.searchView)

        searchView.setOnQueryTextListener(object: SearchView.OnQueryTextListener{
            override fun onQueryTextSubmit(p0: String?): Boolean {
                return false
            }

            override fun onQueryTextChange(p0: String?): Boolean {
                var rs = contentResolver.query(
                    ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                    cols, "${ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME} LIKE ?", Array(1){"%$p0%"},
                    ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME)
                adapter.changeCursor(rs)
                return false
            }
        })
    }
}