MainActivity.kt
package com.cfsuman.kotlintutorials
import android.app.Activity
import android.os.Bundle
import android.widget.*
class MainActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// get the widgets reference from XML layout
val button = findViewById<Button>(R.id.button)
val listView = findViewById<ListView>(R.id.listView)
val textView = findViewById<TextView>(R.id.textView)
// list to populate list view
val list = mutableListOf(
"Black bean",
"Black coffee",
"Black chocolate",
"French lilac",
"Bronze",
"Dark sienna",
"Deep taupe",
"Fern green"
)
// show the list size
textView.text = "List elements : ${list.size}"
// 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 = AdapterView.OnItemClickListener {
parent, view, position, id ->
val selectedItem = parent.getItemAtPosition(position)
textView.text = "Selected : $selectedItem"
}
// remove list view items programmatically
button.setOnClickListener {
// disable the button itself
it.isEnabled = false
// remove list view item by element name
list.remove("Black coffee")
// remove item by index
list.removeAt(3)
// remove all elements which name ends with "c"
list.removeAll {
it.endsWith("c",false)
}
// remove all elements that match the collection
val elementsToRemove = listOf("Cameo pink","Dark sienna")
list.removeAll(elementsToRemove)
// remove if element starts with "f", ignore case
list.removeIf {
it.startsWith("f",ignoreCase = true)
}
// show the list size, after removing elements
textView.text = "List elements : ${list.size}"
// 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"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/rootLayout"
android:background="#DCDCDC"
android:padding="24dp">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Remove Items"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ListView
android:id="@+id/listView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="24dp"
app:layout_constraintBottom_toTopOf="@+id/textView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/button" />
<TextView
android:id="@+id/textView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:fontFamily="sans-serif"
android:gravity="center"
android:textColor="#333399"
android:textSize="24sp"
android:textStyle="italic"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>


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