Sunday, October 20, 2019

android kotlin - take, takeLast, takeWhile, takeLastWhile example

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','e','f','a','a','g','g','h','i')

        btn.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"
    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"
        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:layout_marginTop="8dp"
        android:text="takeWhile"
        app:layout_constraintStart_toEndOf="@+id/btn"
        app:layout_constraintTop_toTopOf="parent" />
    <Button
        android:id="@+id/btnTakeLastWhile"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="takeLastWhile"
        app:layout_constraintStart_toEndOf="@+id/btnTakeWhile"
        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" />
</androidx.constraintlayout.widget.ConstraintLayout>
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