LESSON 1 INTRODUCTION Compiled By: Edwin O. Okech [Tutor, Amoud University] JAVA PROGRAMMING

Outline Compiled By: Edwin O. Okech [Tutor, Amoud University] The origin of Java. The Java history. The capabilities of Java programming language. The Java language specifications The Java API The Java development tools How does byte code makes Java a portable language?

Origin of Java Compiled By: Edwin O. Okech [Tutor, Amoud University] In 1991, Java was developed by a team led by James Gosling and Patrick Naughton at Sun Microsystems. Originally named Oak ‐ Gosling liked the look of an oak tree that was outside his window at Sun.

History of Java Compiled By: Edwin O. Okech [Tutor, Amoud University] The challenge: For use in embedded consumer electronic appliances ‐ the cable TV switchboxes.  Different manufacturers may choose different central processing units (CPUs).  The cable TV switchboxes devices do not have a lot of power or memory. The language;  Had to be small and generate very tight code.  Not be tied to any single architecture.

History of Java Compiled By: Edwin O. Okech [Tutor, Amoud University] A two ‐ step Java translation process have been developed:  Programs written in Java were translated into an intermediate language, known the byte code.  Then, the byte code would be translated into machine language. In 1994, Java was used to develop a Web browser, named HotJava.  The browser able to download and run small Java programs over the internet, known as the applets.  Capable to display animation and interact with the user. In 1995, Netscape incorporated Java technology into its Netscape browser.  Then, other Internet companies followed...

Java Capabilities Compiled By: Edwin O. Okech [Tutor, Amoud University] Java is a full ‐ featured and general ‐ purpose programming language that is capable of developing a robust mission ‐ critical applications for:  Desktops  Servers  Mobile devices The Java programming language is a relatively highlevel language, class ‐ based and object ‐ oriented.

Java Capabilities Compiled By: Edwin O. Okech [Tutor, Amoud University] Java running on the desktop is called application. Java running on the Internet is called applets. Java developed on the server ‐ side is called servlet.

Java Language Specification Compiled By: Edwin O. Okech [Tutor, Amoud University] Defines the Java standard and the technical definition of the language.  includes the syntax and semantics of the language.  url: java.sun.com/docs/books/jls

Java Application Programming Interface Compiled By: Edwin O. Okech [Tutor, Amoud University] Java application program interface (API) contains the predefined classes and interfaces for developing Java programs. In 1995, Java 1.0 was introduced.  With 211 classes and interfaces. In December 1998, Java 2 platform was announced.  Applies to current Java technology.

Java API Compiled By: Edwin O. Okech [Tutor, Amoud University]

Java API Compiled By: Edwin O. Okech [Tutor, Amoud University] There are 3 editions of the Java API:  Java 2 standard edition (J2SE) Client ‐ side standalone applications or applets.  Java 2 Enterprise Edition (J2EE) Server ‐ side applications, such as Java servlets and  JavaServer Pages. Java 2 Micro Edition (J2ME)  Mobile devices, such as cell phones or pda.

Demonstrate how to link to Java API Compiled By: Edwin O. Okech [Tutor, Amoud University] J2SE versions and JDK There are many versions of J2SE.  Sun releases each version of J2SE with a Java Development toolkit (JDK). JDK consists of a set of separate programs for developing and testing Java programs.  Each of which is invoked from a command line. For J2SE 5.0, the Java development toolkit is called JDK 5 – formerly was known as JDK1.5.  The latest version is J2SE 6.

Java Development Tools Compiled By: Edwin O. Okech [Tutor, Amoud University] A software that provides an integrated development environment (IDE) for rapidly developing Java programs. Java development tools on the market:  NetBeans by Sun (open source)  JBuilder by Borland  Eclipse by IBM (open source) Other useful tools:  Code warrior by Metroworks  TextPad Editor  JCreator LE  Jedit  BlueJ

Byte-code The Java Virtual Machine Compiled By: Edwin O. Okech [Tutor, Amoud University] The Java compiler translates Java programs into byte ‐ code.  Once compiled to byte ‐ code, a Java program can be used on any computer, making it very portable machine. The Java Virtual Machine (JVM) translates the byte code into machine language.

Portable Compiled By: Edwin O. Okech [Tutor, Amoud University] Portable means that a program may be written on one type of computer and then run on a wide variety of computers, with little or no modification. Java byte code runs on the JVM and not on any particular CPU; therefore, compiled Java programs are highly portable. JVMs exist on many platforms:  Windows  Macintosh  Linux

Portability Compiled By: Edwin O. Okech [Tutor, Amoud University] Portability Byte Code JVM For Windows JVM For Linux JVM For Macintosh JVM For Unix