Monday, October 21, 2019

android kotlin - List sort and sortDescending 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)

        btn.setOnClickListener {
            val list = mutableListOf('x','c','z','a','y','p','b','d','u')
            textView.text = "List: "
            // 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: "
            // 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: "
            // 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"
    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="List"
        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:layout_marginTop="8dp"
        android:text="Sort"
        app:layout_constraintStart_toEndOf="@+id/btn"
        app:layout_constraintTop_toTopOf="parent" />
    <Button
        android:id="@+id/btnSortDescending"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="Sort Descending"
        app:layout_constraintStart_toEndOf="@+id/btnSort"
        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>
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