android studio spinner saving value when going back

The first step for declaring values is to determine whether to declare it with val or var. The app is quite simple, because the focus of the tutorial will be on values and declarations, instead of the Android UI! Declaring Values It’s enough to interact with spinners to see the calculated result. Every element of the layout has a TextView above itself with instructions for use. The app contains a ConstraintLayout with one EditText for inserting the desired temperature value, two Spinner widgets for the initial and final measurement unit, and a TextView for displaying a result. Right now, you’re not able to experiment with conversions, but don’t worry, because you’ll implement all you need to use the app! Build and run on a device to see how the app looks. Tempco is a single-screen app for converting temperature values between Fahrenheit, Celsius and Kelvin measurement units.

In this tutorial, you’ll use the Tempco app. If you aren’t familiar with Android Studio or you haven’t installed it yet, refer to our Beginning Android Development tutorials.ĭownload the starter project by clicking the Download Materials button at the top or bottom of the tutorial. Note: This tutorial assumes a basic knowledge of Android Studio and Kotlin. The difference between static values and inline values.The way to declare a constant and where to use it.The difference between lazy initialization and late initialization.How to declare immutable values and where to use them.How to declare mutable values, also known as variables, and where to use them.In this tutorial, you’ll implement them and discover more about the differences between them. There are three possible ways of creating values in Kotlin - by using var, val and const val before a value name. Considering Kotlin has several ways to define values across code, you probably had a hard time finding the best suitable solution.įinally, here’s a tutorial to address all your doubts! :] If the answer is yes, you most likely wondered if you should define those values inside or outside a class and which keywords you need to use. Have you ever had to declare a counter field or save an index of the last selected item in a list? Or did you need to save a license key for a third-party library such as Google Maps? Values and mutability are features all programming languages need to provide. In this Values and Mutability tutorial, you’ll learn how to declare mutable, immutable, constant, late/lazily initialized, static & inline values.

Android studio spinner saving value when going back