Sunday, January 21, 2018

android kotlin - For loop range 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);
        val button3 = findViewById<Button>(R.id.button3);
        val button4 = findViewById<Button>(R.id.button4);

        // For loop example, simple range
        button.setOnClickListener{
            textView.text = "For loop 1 to 10 \n"
            // Loop through the range
            for (i in 1..10){
                textView.text = textView.text.toString() +" " + i + "\n"
            }
        }

        // For loop down to example
        button2.setOnClickListener{
            textView.text = "For loop 10 down to 1 \n"
            for(i in 10 downTo 1){
                textView.text = textView.text.toString() + " " + i + "\n"
            }
        }

        // For loop range 1 to 10 and step 2
        button3.setOnClickListener{
            textView.text = "For loop 1 to 10 and step 2 \n"
            for (i in 1..10 step 2){
                textView.text = textView.text.toString() + " " + i + "\n"
            }
        }

        // For loop range 10 down to 1 and step 2
        button4.setOnClickListener{
            textView.text = "For loop 10 down to 1 and step 2 \n"
            for (i in 10 downTo 1 step 2){
                textView.text = textView.text.toString() + " " + i + "\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="Range 1..10"
        />
    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Range 10 down to 1"
        />
    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Range 1..10 Step 2"
        />
    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Range 10..1 Step 2"
        />
    <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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