Android™ How to Program, Second Edition

I.3. Text Fields and an Introduction to Event Handling with Nested Classes

Normally, a user interacts with an app’s GUI to indicate the tasks that the app should perform. For example, when you write an e-mail in an e-mail app, clicking the Send button tells the app to send the e-mail to the specified e-mail addresses. GUIs are event driven. When the user interacts with a GUI component, the interaction—known as an event—drives the program to perform a task. Some common user interactions that cause an app to perform a task include clicking a button, typing in a text field, selecting an item from a menu, closing a window and moving the mouse. The code that performs a task in response to an event is called an event handler, and the overall process ...