Android Multi Select Spinner example kotlin

Output:

1/  Modify the activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    >

    <com.google.android.material.card.MaterialCardView
        android:id="@+id/cardv"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:layout_centerInParent="true"
        android:layout_marginLeft="40dp"
        android:layout_marginRight="40dp">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/tvitem"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_marginLeft="10dp"
                android:gravity="center"
                android:text="Select the item "
                android:textSize="15sp"
                android:textStyle="bold|italic" />

            <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:layout_alignParentTop="true"
                android:layout_alignParentEnd="true"
                android:src="@drawable/baseline_arrow_drop_down_circle_24" />

        </RelativeLayout>

    </com.google.android.material.card.MaterialCardView>
</RelativeLayout>

2 /Modify the MainActivity.java

package com.zissofworks.multiselectspinner

import android.app.AlertDialog
import android.os.Bundle
import android.widget.TextView
import androidx.activity.enableEdgeToEdge
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
import com.google.android.material.card.MaterialCardView


class MainActivity : AppCompatActivity() {
    lateinit var cardv: MaterialCardView
    lateinit var tvitem: TextView
    var arrayList: ArrayList<Int> = ArrayList()
    var arrayitem: Array<String> = arrayOf("book", "pensil", "pen", "sheet")
    lateinit var selectitem: BooleanArray

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContentView(R.layout.activity_main)
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)) { v, insets ->
            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
            insets
        }

        selectitem = BooleanArray(arrayitem.size)

        cardv = findViewById(R.id.cardv)
        tvitem = findViewById(R.id.tvitem)


        cardv.setOnClickListener {
            showAltItem();
        }
    }

    private fun showAltItem() {

        val builder = AlertDialog.Builder(this)
        builder.setTitle("Select Item")
        builder.setCancelable(false)

        builder.setMultiChoiceItems(arrayitem, selectitem) { _, which, isChecked ->
            if (isChecked) {
                arrayList.add(which)
            } else {
                arrayList.remove(which)
            }
        }
            .setPositiveButton("OK") { _, _ ->
            }
            .setNegativeButton("Cancel") { _, _ ->
            }
            .setNeutralButton("Clear All") { _, _ ->
            }

        builder.show()
    }
}