Monday, March 9, 2020

android kotlin - ListView add item programmatically

MainActivity.kt 

package com.example.jetpack

import android.os.Bundle
import android.widget.AdapterView.OnItemClickListener
import android.widget.ArrayAdapter
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

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

        // list to populate list view
        val list = mutableListOf(
            "Antique ruby",
            "Bitter lemon"
        )

        // initialize an array adapter
        val adapter:ArrayAdapter<String> = ArrayAdapter(
            this,
            android.R.layout.simple_dropdown_item_1line,list
        )

        // attach the array adapter with list view
        listView.adapter = adapter

        // list view item click listener
        listView.onItemClickListener = OnItemClickListener{
                parent, view, position, id ->
            val selectedItem = parent.getItemAtPosition(position)
            textViewResult.text = "Selected : $selectedItem"
        }


        // add list view items programmatically
        button.setOnClickListener {
            // add an items to list view bottom
            list.add("Black bean")

            // add an item to list first
            list.add(0,"Blue sapphire")

            // insert multiple items at a time
            val newItems = listOf("Brick red","Bright green")
            list.addAll(newItems)

            // insert element at index 5 position
            if(list.size>=5){
                list.add(5,"Cadmium red")
            }

            // finally, notify the adapter for data set changed
            adapter.notifyDataSetChanged()
        }
    }
}
activity_main.xml 

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    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/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.google.android.material.button.MaterialButton
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="8dp"
        android:text="Add Items"
        android:backgroundTint="#1560BD"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:background="#F5F5F5"
        android:choiceMode="singleChoice"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/textViewResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="16dp"
        android:textAppearance=
            "@style/TextAppearance.MaterialComponents.Subtitle1"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        tools:text="TextView" />

</androidx.constraintlayout.widget.ConstraintLayout>
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