android kotlin - List sort and sortDescending example

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 btnSort = findViewById<Button>(R.id.btnSort)
        val btnSortDescending = findViewById<Button>(
            R.id.btnSortDescending)


        // make textview content scrollable
        textView.movementMethod = ScrollingMovementMethod()


        btnList.setOnClickListener {
            val list = mutableListOf('x','c','z','a',
                'y','p','b','d','u')
            textView.text = "List :\n"
            // Iterate through the list
            list.forEach {
                textView.append("$it, ")
            }
        }


        btnSort.setOnClickListener {
            val list = mutableListOf('x','c','z','a',
                'y','p','b','d','u')
            list.sort()

            textView.text = "List sorted :\n"
            // Iterate through the list
            list.forEach {
                textView.append("$it, ")
            }
        }


        btnSortDescending.setOnClickListener {
            val list = mutableListOf('x','c','z','a',
                'y','p','b','d','u')
            // return Unit
            list.sortDescending()

            textView.text = "List sorted descending :\n"
            // Iterate through the list
            list.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/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/btnSort"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="Sort"
        android:textAllCaps="false"
        app:layout_constraintBottom_toBottomOf="@+id/btnList"
        app:layout_constraintStart_toEndOf="@+id/btnList" />

    <Button
        android:id="@+id/btnSortDescending"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="Sort Descending"
        android:textAllCaps="false"
        app:layout_constraintBottom_toBottomOf="@+id/btnSort"
        app:layout_constraintStart_toEndOf="@+id/btnSort" />

    <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>

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