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

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).

CodePudding user response：

You can use intent to send and receive data you want to transfer from FirstActivity to SecondActivity. Hope this post can help you passing data from list view to another activity

CodePudding user response：

First thing first, initialise your compList variable, it is null as I cannot see any initialisation of the variable in the mentioned code.

Now when you try to add the item in onItemClick() because of null safety check it is neither returning any exception nor adding value to compList.

try to debug if the values are inserted in compList array. hope this helps, thanks!