Building Mobile Applications with Java

Chapter 4. Customizing Your App for Mobile

So far we have gotten our example app onto a mobile device, but that doesn’t really make it ready for mobile. Mobile devices are different than desktop computers. Not only do they have smaller screens but they are also usually touch driven. Fingers are bigger than a mouse cursor. Certain actions, like scrolling, are easier to do with a finger, whereas other actions like opening drop down menus are harder or impossible to do without a mouse.

Finally, mobile devices typically have a slower network connection and less processing power than a full blown desktop or laptop. You must take all of these complications into account in order to create a great mobile experience, and that is before we even consider mobile specific features like GPS and accelerometers.

In this section we will take a look at the ways mobile devices are different and how to adapt content and applications to these new constraints.

CSS Overview

Fundamentally GWT builds apps with the technology of web pages. Even though we almost never have to touch the HTML markup directly, GWT is using HTML, JavaScript, and CSS underneath. Most modern web sites use HTML only to represent the content of a page or application. The visuals and styling are controlled using a separate document called a Cascading Style Sheet, or CSS file. A CSS file controls the drawing of each element on the screen. It controls both how it is drawn: the colors, backgrounds, fonts, and effects; as well as where it ...