MainActivity.kt
package com.example.jetpack
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val list = mutableListOf('a','a','b','b','c','d','a','e','b','f','a','a','b','g','h','i')
btn.setOnClickListener {
textView.text = " List: "
list.forEach { textView.append("$it, ") }
// takeWhile only returns by matching condition and take first elements of the list
val taken = list.takeWhile { it == 'a' }
textView.append("\n\nlist.takeWhile { it == 'a' }")
taken.forEach {
textView.append("\n$it")
}
val filtered = list.filter { it == 'a' }
textView.append("\n\nlist.filter { it == 'a' }")
filtered.forEach {
textView.append("\n$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"
tools:context=".MainActivity">
<Button
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Take While vs Filter"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="16dp"
android:padding="16dp"
android:text="List Example"
android:textAppearance="@style/TextAppearance.AppCompat.Medium"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/btn"
android:textStyle="bold"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
