MainActivity.kt
package com.cfsuman.kotlinexamples
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.Toast
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Get the widgets reference from xml layout
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);
// Function test with no argument and void return
button.setOnClickListener{
sayHello()
}
// Function test with an argument
button2.setOnClickListener{
showToast("This is a simple toast.")
}
// Function test with arguments and return value
button3.setOnClickListener{
var sum = sum(5,10)
Toast.makeText(applicationContext,"Sum is $sum",Toast.LENGTH_SHORT).show()
}
// Function without {} curly braces
// Function returns single expression
button4.setOnClickListener{
var fullName: String = getFullName("Suhailah", "Alam")
Toast.makeText(applicationContext,fullName,Toast.LENGTH_SHORT).show()
}
}
// Function with no argument and no return value
fun sayHello(): Unit{
Toast.makeText(applicationContext,"Hello Kotlin!",Toast.LENGTH_SHORT).show()
}
// Function with an argument and return type void
fun showToast(message: String){
Toast.makeText(applicationContext,message,Toast.LENGTH_SHORT).show()
}
// Function with arguments and return value
fun sum(a: Int, b: Int):Int{
return a+b
}
// Single line expression function
fun getFullName(first: String, last: String): String = "$first $last"
}
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="Function + No Argument + Void"
/>
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Function + Argument + Void"
/>
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Function + Argument + Return"
/>
<Button
android:id="@+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Single Line Function"
/>
</LinearLayout>




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