Category: Kotlin

Most Android-based devices use a touch screen as the primary interface between the user and the device. The previous chapter introduced how a touch on the screen translates into an action within a running Android application. There is, however, much more to touch event handling than responding to a single finger tap on a view…

Much has been covered in the previous chapters relating to the design of user interfaces for Android applications. However, an area that has yet to be covered involves how a user’s interaction with the user interface triggers the underlying activity to perform a task. In other words, from the previous chapters, we know how to…

Now that some of the basic concepts of Android development using Android Studio have been covered, this is a good time to introduce the Android Studio Apply Changes feature. As all experienced developers know, every second spent waiting for an app to compile and run is better spent writing and refining code. Introducing Apply Changes…

The previous chapter introduced the basic concepts of creating and modifying user interface layouts in Kotlin code using the ConstraintLayout and ConstraintSet classes. This chapter will put these concepts into practice by creating an example layout created entirely in Kotlin code and without using the Android Studio Layout Editor tool. Creating the Example Project in…

Until this point in the book, all user interface design tasks have been performed using the Android Studio Layout Editor tool, either in text or design mode. An alternative to writing XML resource files or using the Android Studio Layout Editor is to write Kotlin code to directly create, configure and manipulate the view objects…

While the design of layouts using the Android Studio Layout Editor tool greatly improves productivity, it is still possible to create XML layouts by manually editing the underlying XML. This chapter will introduce the basics of the Android XML layout file format. Manually Creating an XML Layout The structure of an XML layout file is…

The easiest and most productive way to design a user interface for an Android application is to use the Android Studio Layout Editor tool. This chapter will provide an overview of how to create a ConstraintLayout-based user interface using this approach. The exercise included in this chapter will also be used as an opportunity to…

The previous chapters have introduced the key features of the ConstraintLayout class and outlined the best practices for ConstraintLayout-based user interface design within the Android Studio Layout Editor. Although the concepts of ConstraintLayout chains and ratios were outlined in the chapter entitled A Guide to the Android ConstraintLayout, we have not yet addressed how to…

As mentioned more than once in previous chapters, Google has made significant changes to the Android Studio Layout Editor tool, many of which were made solely to support user interface layout design using ConstraintLayout. Now that the basic concepts of ConstraintLayout have been outlined in the previous chapter, this chapter will explore these concepts in…

As discussed in the chapter entitled Android Views, View Groups, and Layouts, Android provides several layout managers to design user interfaces. With Android 7, Google introduced a layout that addressed many of the shortcomings of the older layout managers. This layout, called ConstraintLayout, combines a simple, expressive, and flexible layout system with powerful features built…