Android Studio – How to send checked items in List View to another activity with Android Studio Kotlin

I have a list of courses in my String resource file.
”’
resources>

   <string name="app_name">SecondPart</string>
    <string name="done">Done</string>
    <string-array name="courses">
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>
        <item>Introduction To Programming</item>



    </string-array>

</resources>

”’

This is my activity_main.xml
”’

<?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">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/multiple_list_view"
        android:layout_weight="1"
        android:dividerHeight="3dp"
        android:divider="@color/black"
        />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/butto"
        android:text="@string/done"/>

</LinearLayout>

”’

Here is my mainActivity.kt
”’

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.*

class MainActivity : AppCompatActivity(), AdapterView.OnItemClickListener  {
    private var listView:ListView ? = null
    private  var arrayAdapter: ArrayAdapter<String> ? = null
    private var complist: ArrayList<String>?= null

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


        listView=findViewById(R.id.multiple_list_view)
        arrayAdapter = ArrayAdapter(applicationContext, android.R.layout.simple_list_item_multiple_choice,
            resources.getStringArray(R.array.courses))
        listView?.adapter = arrayAdapter
        listView?.choiceMode = ListView.CHOICE_MODE_MULTIPLE
        listView?.onItemClickListener = this

        val but : Button = findViewById(R.id.butto)

        but.setOnClickListener{
           

}

    }

    override fun onItemClick(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
        var items:String = parent?.getItemAtPosition(position) as String
        complist?.add(items)

        Toast.makeText(applicationContext, "CourseName : $items", Toast.LENGTH_SHORT).show()


    }


}

”’
In the mainActivity.kt, I have made an ArrayList called as complist.
Whenever the onItemClick is called ie any item in ListView is checked, I am able to print on terminal and make a toast. So I thought I can add those Strings in ArrayList.

This arraylist is not working.

I want to capture all those selected items as a String Array List and when the button is pressed ( setOnClickListener ), I want to send those items to be sent to another activity as the intent (putExtra).