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JAVA PROGRAMMING
LESSON 1
INTRODUCTION
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Outline
 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?
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Origin of Java
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
History of Java
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
History of Java
 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 . . .
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java Capabilities
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java Capabilities
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java Language Specification
 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
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java Application Programming
Interface
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java API
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java API
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Demonstrate how to link to Java
API
 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.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Java Development Tools
 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
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Byte-code The Java Virtual Machine
 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 JavaVirtual Machine (JVM) translates the byte code into
machine language.
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Portable
 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
Compiled By: Edwin O. Okech [Tutor, Amoud University]
Portability
 Portability
Byte Code
JVM For
Unix
JVM For
Windows
JVM For
Linux
Compiled By: Edwin O. Okech [Tutor, Amoud University]
JVM For
Macintosh