In order to be able to handle the event that it has been passed, the view must have in place an event listener.

In addition to the event notification, the view is also passed a range of information (depending on the event type) about the nature of the event such as the coordinates of the point of contact between the user’s fingertip and the screen. In the case of an input event such as a touch on the screen, the event is passed to the view positioned at the location on the screen where the touch took place. Events are then removed from the queue on a first-in, first-out (FIFO) basis. The Android framework maintains an event queue into which events are placed as they occur.

Such events fall into the category of input events. The most common form of events, particularly for devices such as tablets and smartphones, involve some form of interaction with the touch screen. Once the basics of event handling have been covered, the next chapter will cover touch event handling in terms of detecting multiple touches and touch motion.Įvents in Android can take a variety of different forms, but are usually generated in response to an external action. The primary objective of this chapter, therefore, is to provide an overview of event handling in Android applications together with an Android Studio based example project. In other words, we know from the previous chapters how to create a user interface containing a button view, but not how to make something happen within the application when it is touched by the user. An area that has yet to be covered, however, involves the way in which a user’s interaction with the user interface triggers the underlying activity to perform a task.

Much has been covered in the previous chapters relating to the design of user interfaces for Android applications. Purchase the fully updated Android Studio Chipmunk Edition of this publication in eBook ($29.99) or Print ($46.99) formatĪndroid Studio Chipmunk Essentials - Java Edition Print and eBook (PDF) editions contain 94 chapters and over 800 pages You are currently reading the Android Studio 1.x - Android 5 Edition of this book.

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