MainActivity.kt
package com.cfsuman.kotlintutorials
import android.os.Bundle
import android.text.method.ScrollingMovementMethod
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// get the widgets reference from XML layout
val textView = findViewById<TextView>(R.id.textView)
val btnList = findViewById<Button>(R.id.btnList)
val btnTakeIf = findViewById<Button>(R.id.btnTakeIf)
val btnTakeUnless = findViewById<Button>(
R.id.btnTakeUnless)
// make textview content scrollable
textView.movementMethod = ScrollingMovementMethod()
val list = generateList()
btnList.setOnClickListener {
textView.text = "Employees:\n"
// Iterate through the list
list.forEach {
textView.append("\n${it.name} : age ${it.age}" +
" : salary $${it.salary}")
}
}
btnTakeIf.setOnClickListener {
textView.text = "Take if list is not empty:\n"
list.takeIf {
it.isNotEmpty() // required boolean
}.apply {
this?.forEach {
// do the task
textView.append("\n" + it.name)
}
}
}
btnTakeUnless.setOnClickListener {
textView.text = "Take unless list is empty:\n"
list.takeUnless {
it.isEmpty()// required boolean
}.apply {
this?.forEach {
// do the task
textView.append("\n" + it.name)
}
}
}
}
}
// Method to generate employee list
private fun generateList():MutableList<Employee>{
val list = mutableListOf<Employee>()
list.add(Employee("Weston",25,6500))
list.add(Employee("Gregg",29,5400))
list.add(Employee("Erika",24,5200))
list.add(Employee("Ashly",19,4900))
list.add(Employee("Tristian",20,2600))
list.add(Employee("Violette",23,4650))
list.add(Employee("Viviane",37,5100))
list.add(Employee("Kyra",48,4100))
list.add(Employee("Uriel",19,2300))
list.add(Employee("Isaias",16,6800))
return list
}
// Data class for Employee
data class Employee(
val name:String,
val age:Int,
val salary:Int
)
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:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#F8F8F8"
android:padding="24dp">
<Button
android:id="@+id/btnList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="List"
android:textAllCaps="false"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btnTakeIf"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="takeIf"
android:textAllCaps="false"
app:layout_constraintBottom_toBottomOf="@+id/btnList"
app:layout_constraintStart_toEndOf="@+id/btnList" />
<Button
android:id="@+id/btnTakeUnless"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="takeUnless"
android:textAllCaps="false"
app:layout_constraintBottom_toBottomOf="@+id/btnTakeIf"
app:layout_constraintStart_toEndOf="@+id/btnTakeIf" />
<TextView
android:id="@+id/textView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginTop="16dp"
android:fontFamily="sans-serif"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/btnList" />
</androidx.constraintlayout.widget.ConstraintLayout>



- kotlin syntax - ArrayList
- kotlin syntax - List add item
- kotlin syntax - List filter
- kotlin syntax - List filter with multiple conditions
- kotlin syntax - filter list by another list
- kotlin syntax - take, takeLast, takeWhile, takeLastWhile
- kotlin syntax - Difference between takeWhile and filter
- kotlin syntax - List sorted and sortedDescending
- kotlin syntax - List sort by multiple fields
- kotlin syntax - Sort list using comparator