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 btnTake = findViewById<Button>(R.id.btnTake)
val btnTakeWhile = findViewById<Button>(R.id.btnTakeWhile)
val btnTakeLastWhile = findViewById<Button>(
R.id.btnTakeLastWhile)
// make textview content scrollable
textView.movementMethod = ScrollingMovementMethod()
val list = mutableListOf('a','a','b','b','c','d','a',
'e','e','f','a','a','g','g','h','i')
btnTake.setOnClickListener {
textView.text = " List: "
list.forEach { textView.append("$it, ") }
val taken = list.take(5)
textView.append("\n\n list.take(5)\n")
taken.forEach {
textView.append("$it, ")
}
val takenLast = list.takeLast(4)
textView.append("\n\n list.takeLast(4)\n")
takenLast.forEach {
textView.append("$it, ")
}
}
btnTakeWhile.setOnClickListener {
textView.text = " List: "
list.forEach { textView.append("$it, ") }
val taken = list.takeWhile { it == 'a' }
textView.append("\n\n list.takeWhile { it == 'a' }\n")
taken.forEach {
textView.append("$it, ")
}
}
btnTakeLastWhile.setOnClickListener {
textView.text = " List: "
list.forEach { textView.append("$it, ") }
val taken = list.takeLastWhile { it > 'e' }
textView.append("\n\n list.takeLastWhile " +
"{ it > 'e' }\n")
taken.forEach {
textView.append("$it, ")
}
}
}
}
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/btnTake"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="take"
android:textAllCaps="false"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btnTakeWhile"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="takeWhile"
android:textAllCaps="false"
app:layout_constraintBottom_toBottomOf="@+id/btnTake"
app:layout_constraintStart_toEndOf="@+id/btnTake" />
<Button
android:id="@+id/btnTakeLastWhile"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="takeLastWhile"
android:textAllCaps="false"
app:layout_constraintBottom_toBottomOf="@+id/btnTakeWhile"
app:layout_constraintStart_toEndOf="@+id/btnTakeWhile" />
<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/btnTake" />
</androidx.constraintlayout.widget.ConstraintLayout>



- kotlin syntax - List filter with multiple conditions
- kotlin syntax - filter list by another list
- kotlin syntax - takeIf and takeUnless
- kotlin syntax - Difference between takeWhile and filter
- kotlin syntax - List sortBy and sortByDescending
- kotlin syntax - List sort and sortDescending
- kotlin syntax - List sort descending using multiple fields
- kotlin syntax - List sort multiple fields by both orders
- kotlin syntax - forEachIndexed
- kotlin syntax - joinToString