android kotlin - withIndex library function example

MainActivity.kt


package com.cfsuman.kotlinexamples

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView


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.text_view)
        val button = findViewById<Button>(R.id.button);
        val button2 = findViewById<Button>(R.id.button2);

        // A simple string variable
        var city = "Khulna"

        // Loop through the string characters using withIndex library function
        button.setOnClickListener{
            textView.text = "Loop string [$city] using withIndex library function \n\n"
            for ((index,value) in city.withIndex()){
                textView.text = textView.text.toString() + "index  = $index, value = $value \n"
            }
        }

        // Loop through the string characters
        button2.setOnClickListener{
            textView.text = "Loop through the string [$city] characters \n\n"
            for (letter in city){
                textView.text = textView.text.toString() + "$letter \n"
            }
        }
    }
}

activity_main.xml


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/root_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    >
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Loop String Using WithIndex Library"
        />
    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Loop String normally"
        />
    <TextView
        android:id="@+id/text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text=""
        android:textSize="18sp"
        android:textStyle="bold"
        android:textColor="#ff191d"
        android:layout_marginTop="20dp"
        />
</LinearLayout>

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