Note for Mobile Application Development - MAD By JNTU Heroes
- Mobile Application Development - MAD
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- Jawaharlal Nehru Technological University Anantapur (JNTU) College of Engineering (CEP), Pulivendula, Pulivendula, Andhra Pradesh, India - JNTUACEP
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LECTURE NOTES MOBILE APPLICATION DEVELOPMENT IV-IT(I-SEM) 1
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UNIT-1 J2ME Overview: Java 2 Micro Edition and the world of Java, Inside J2ME, J2ME and Wireless Devices small Computing Technology. Wireless Technology, Radio Data Networks, Microwave Technology, Mobile Radio Networks, Messaging, Personal Digital Assistants 4
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Cell phones, digital set-top boxes for cable television, car navigationsystems, pagers, and personal digital assistants are all computers. And computers are also used to control the operation of automobiles, industrial equipment, and household appliances. This new breed of computers, referred to as small computing devices, is distinguishable from more traditional computers by their reduced resource availability. Resources such as memory, permanent storage, and power are plentiful in traditional computers but are precious in small computing devices. Along with the new breed of computers came a new platform, on which developers can build and implement programs to control small computing devices. The platform is called Java 2 Micro Edition (J2ME). You’ll be introduced to J2ME in this chapter. Java 2 Micro Edition and the World of Java The computer revolution of the 1970s increased the demand for sophisticated computer software to take advantage of the ever-increasing capacity of computers to process data. The C programming language became the linchpin that enabled programmers to build software that was just as robust as the computer it ran on. As the 1980s approached, programmers were witnessing another spurt in the evolution of programming language. Computer technology advanced beyond the capabilities of the C programming language. The problem wasn’t new. It occurred previously and caused the demise of generations of programming languages. The problem was that programs were becoming too complicated to design, write, and manage to keep up with the capabilities of computers. It was around this time that a design concept based on Simula 67 and Smalltalk (from the late 1960s) moved programming to the next evolutionary step. This was the period when object-oriented programming (OOP), and with it a new programming language called C++, took programmers by storm. In 1979, Bjarne Stroustrup of Bell Laboratories in New Jersey enhanced the C programming language to include object-oriented features. He called the language C++. (The ++ is the incremental operator in the C programming language.) C++ is truly an enhancement of the C programming language, and it began as a preprocessor language that was translated into C syntax before the program was processed by the compiler. Stroustrup built on the concept of a class (taken from Simula 67 and Smalltalk), from which instances of objects are created. A class contains data members and member functions that define an object’s data and functionality. He also introduced the concept of inheritance, which enabled a class to inherit some or all data members and member functions from one or more other classes—all of which complements the concepts of object-oriented programming. By 1988, ANSI officials standardized Stroustrup’s C++ specification. 5
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Enter Java Just as C++ was becoming the language of choice for building industrial-strength applications, another growth spurt in the evolution of programming language was budding, fertilized by the latest disruptive technology—the World Wide Web. The Internet had been a well-kept secret for decades before the National Science Foundation (who oversaw the Internet) removed barriers that prevented commercialization. Until 1991 when it was opened to commerce, the Internet was the almost exclusive domain of government agencies and the academic community. Once the barrier to commercialization was lifted, the World Wide Web—one of several services offered on the Internet— became a virtual community center where visitors could get free information about practically anything and browse through thousands of virtual stores. Browsers power the World Wide Web. A browser translates ASCII text files written in HTML into an interactive display that can be interpreted on any machine. As long as the browser is compatible with the correct version of HTML and HTTP implementation, any computer running the browser can use the same HTML document without having to modify it for a particular type of computer, which was something unheard of at the time. Programs written in C or C++ are machine dependent and cannot run on a different machine unless the program is recompiled. The success of the Internet gave renewed focus to developing a machine-independent programming language. And the same year the Internet was commercialized, five technologists at Sun Microsystems set out to do just that. James Gosling, Patrick Naughton, Chris Warth, Ed Frank, and Mike Sheridan spent 18 months developing the programming language they called Oak, which was renamed Java when this new language made its debut in 1995. Java went through numerous iterations between 1991 and 1995, during which time many other technologists at Sun made substantial contributions to the language. These included Bill Joy, Arthur van Hoff, Jonathan Payne, Frank Yelin, and Tim Lindholm. Although Java is closely associated with the Internet, it was developed as a language for programming software that could be embedded into electronic devices regardless of the type of CPU used by the device. This is known as the EmbeddedJava platform and is in continuous use today for closed systems. The Java team from Sun succeeded in creating a portable programming language, something that had eluded programmers since computers were first programmed. Their success, however, was far beyond their wildest dreams. The same concept used to make Java programs portable to electronic devices also could be used to make Java programs run on computers running Microsoft Windows, UNIX, and Macintosh. Timing was perfect. The Internet/intranet had whetted corporate America’s appetite for cost-effective, portable programs that could replace mission-critical applications within the corporation. And Java had proven itself as a programming language used to successfully develop machine-independent applications. It was in the mid-1990s when the team from Sun realized that Java could be easily adapted to develop software for the Internet/intranet. And toward the turn of the century, 6
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