I can highly recommand "Beginning Google Web Toolkit" from Apress if you want to start learning GWT.

The nice thing about this book is that it is based on GWT 1.5 and therefore already uses the Java 1.5 language features. The example from the book is building a GWT based Todo List with different categories, something which is actually quite handy to have.

The only negative thing is that I had the feeling that the book repeats itself a bit too often, e.g. it stressed several times how Java programmer can leverage their existing Java knowledge by using GWT.

What I especially liked about the book that it follows a tutorial style building the whole application step-by-step. The book is also very successful in demonstrating how certain conceptional approaches, e.g. separation of concern and testability can be archived with GWT.

Overall a very good book which makes learning the basic GWT very easy.

This book stands out as a concise Java developers' introduction to GWT with a fantastic example application and a focus on good design. The example application is built up chapter by chapter and serves as a solid demonstration of how you can pimp your standard web app, GWT-style.

While other GWT book examples are stand-alone doodads that don't look much like webapps, this example really hit the spot. It covers logging in, has a (dynamic) left-side menu, titled modal popups, and a status panel. I actually used this app out-of-the-box as a template for my own first GWT application.

The introduction chapters give a lean overview of what you need to know to get you up and running (with proper browser tooling). It also gives a frank discussion of the advantages and current shortcomings of GWT. By chapter three you're programming using the GWT command line tools.

UI chapters follow and are a definite a strong point thanks to the coherent accompanying example application and an emphasis on good design principles. It's telling that the authors, all members of the pioneering Spring Source inner circle, reference Martin Fowler and Joel Spolsky when discussing these design principles (and pitfalls).

In the spirit of the "Separation of Concerns Principle" and avoiding bidirectional dependencies they advocate an application event structure. I eventually decided not to use it for my small app, but I can see the potential maintenance advantages for a large project.

The Server side chapter introduces GWT RPC, complete with a good exception handling strategy. It also discusses making vanilla HTTP requests for interfacing with any web service and explores using GWT's JSON libraries for communicating complex data structures.

There is a complete chapter on unit and functional testing with extensive coverage of Selenium. The authors correctly point out the drawbacks of GWT testing tools and encourage basic unit testing whenever possible. As a side note, the most advanced (purist) thinking on GWT testing comes from their colleague Rob van Maris[...]

The last chapter covers most everything else you'll need to crank out your GWT app including I18N, browser back support, image upload, and custom javascript inclusion.

The only thing I missed was maven integration, but I found that easily in the GWT docs.

Note: one reader was disappointed that there was no discussion of GWT Spring integration. IMO, Spring integration into GWT doesn't really warrant the complexity it introduces. I certainly use Spring on the server side of my app, but for the client-side (GWT-side) it adds very little. Rest assured that the authors, being from the Spring camp, emphasize similar best practices to the ones you'd encounter in Spring (testability, separation of concerns, 00 design, simplicity).

I decided to buy this book(PDF version) because the description of the book mentioned "integration with Spring...so i thought "cool", then after purchasing the pdf version of the book.. NO TOPICS about integration with Spring at all... ZERO!!!!! So i contacted apres and they didn't even bother to email me back... very disappointed.... i havent finished reading the book yet, so I can't give a fair review on the book But I do know.. THERE IS NO TOPIC ABOUT THE INTEGRATION OF SPRING!!!!!