Preface

Programming is the most fun a person can have on their own. This is a fact well-known to programmers, though it seems the rest of the world is yet to catch on. You already know this or you wouldn't be reading this book, but it constantly amazes me that more people aren't falling over themselves to learn to code.

Meanwhile, mobile devices have made computers fun even for non-coders. We carry in our pockets small machines with incredible processing power and a giddying array of sensors and interfaces.

Android takes these fun machines and makes them accessible to programmers through a fabulously well-crafted platform and tool chain, in a programming language that has stood the test of time yet continues to develop and evolve.

What could possibly be better than programming fun machines to do cool things, in a powerful language, on a well-crafted platform, with a world-class tool chain? For me, the answer is doing so with a good enough understanding of those things to make the difference between a good app and a great one.

There are many things that must come together to make a great app. You need a great idea—I can't help you there. You need a pretty user interface—sorry, wrong book. You need a great user experience—aha! Now we're getting somewhere. Among the many things that contribute to a great user experience, responsiveness is right up there near the top of the list.

It's easiest to define responsiveness with examples of its lack: pauses and glitches while scrolling content, user interfaces that freeze while loading data from storage, applications that don't give progress updates to let us know what's happening, failing to complete work that we initiated, staring at a spinner while data is fetched from the network, and the list goes on.

This book is about making the difference between a good app and a great one; smoothing out the glitches, keeping the UI responsive, telling the user how things are going, making sure we finish what we started, using those powerful multicore processors, and doing it all without wasting the battery. Let's have some fun!