WelcometoJava—theworld’smostwidelyusedcomputerprogramminglanguage.You’re already familiar with the powerful tasks computers perform. Using this textbook, you’ll write instructions commanding computers to perform those kinds of tasks. Software (i.e., the instructions you write) controls hardware (i.e., computers). You’ll learn objectoriented programming—today’s key programming methodology. You’ll create and work with many software objects in this text. Java is the preferred language for meeting many organizations’ enterprise programmingneeds. Javahas alsobecomethelanguage ofchoiceforimplementingInternetbased applications and software for devices that communicate over a network. In use today are more than a billion generalpurpose computers and billions more Javaenabled cell phones, smartphones and handheld devices (such as tablet computers). AccordingtoastudybyeMarketer,thenumberofmobileInternetuserswillreachapproximately 134 million by 2013.1 Other studies have projected smartphone sales to surpass personal computer sales in 20112 and tablet sales to account for over 20% of all personal computer sales by 2015.3 By 2014, the smartphone applications market is expected to exceed 40 billion,4 which is creating significant opportunities for programming mobile applications.