How do you display a Toast using Kotlin on Android?

Question

In different Kotlin examples for Android I see toast("Some message...") or toastLong("Some long message"). For example:

view.setOnClickListener { toast("Click") }

As I understand, it is an Extension Function for Activity.

How and where do you define this toast() function so that you are able to use it throughout the project?

Answer 1

It can be an extension function for Context:

fun Context.toast(message: CharSequence) =      Toast.makeText(this, message, Toast.LENGTH_SHORT).show() 

You can place this anywhere in your project, where exactly is up to you. For example, you can define a file mypackage.util.ContextExtensions.kt and put it there as a top level function.

Whenever you have access to a Context instance, you can import this function and use it:

import mypackage.util.ContextExtensions.toast  fun myFun(context: Context) {     context.toast("Hello world!") } 

Answer 2

This is one line solution in Kotlin:

Toast.makeText(this@MainActivity, "Its a toast!", Toast.LENGTH_SHORT).show() 

Answer 3

It's actually a part of Anko, an extension for Kotlin. Syntax is as follows:

toast("Hi there!")
toast(R.string.message)
longToast("Wow, such a duration")

In your app-level build.gradle, add implementation "org.jetbrains.anko:anko-common:0.8.3"

Add import org.jetbrains.anko.toast to your Activity.

Answer 4

Try this

In Activity

Toast.makeText(applicationContext, "Test", Toast.LENGTH_LONG).show()

or

Toast.makeText(this@MainActiivty, "Test", Toast.LENGTH_LONG).show()

In Fragment

Toast.makeText(activity, "Test", Toast.LENGTH_LONG).show()

or

Toast.makeText(activity?.applicationContext, "Test", Toast.LENGTH_LONG).show()