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Published byMagdalene Barrett Modified over 9 years ago
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What is Java? Object Oriented Programming Language Sun Microsystems “Write Once, Run Everywhere” Bytecode and Virtual Machine Java Platform (Java VM and Java API)
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Java History Started 1991 by Gosling, Sheridan, Naughton (“The Green Team”) Oak for Consumer Electronics Mosaic 1993 March 1995 v1.0a2 Netscape and Java, May 23, 1995
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Java As Programming Language Simple Object-Oriented Distributed Interpreted Robust Secure Architecture Neutral Portable High-Performance Multithreaded Dynamic
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What you get with Java The essentials: Objects, strings, threads, numbers, input and output, data structures, system properties, date and time, and so on. Applets: The set of conventions used by applets. Networking: URLs, TCP (Transmission Control Protocol), UDP (User Datagram Protocol) sockets, and IP (Internet Protocol) addresses.
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Internationalization: Help for writing programs that can be localized for users worldwide. Programs can automatically adapt to specific locales and be displayed in the appropriate language. Security: Both low level and high level, including electronic signatures, public and private key management, access control, and certificates. Software components: Known as JavaBeans, can plug into existing component architectures.
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Object serialization: Allows lightweight persistence and communication via Remote Method Invocation (RMI). Java Database Connectivity (JDBC): Provides uniform access to a wide range of relational databases.
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Object Oriented Data Structure and behavior are incorprated in discrete objects identity, classification, polymorphism, inheritance Identity: Data is quantized into discrete, distinguishable entities called objects. Classification: Objects with same attributes and behavior are grouped in classes
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Class: An abstraction that describes properties important to an application and ignores the rest Instance: Each object is an instance of a class. Polymorphism: Same operation may behave differently on different classes. Specific implementation of an operation is a method. Inheritance: Sharing of attributes and operations among classes based on a hierarchical relationship
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OO Development Model Concepts; Not Implementation Analysis System Design Object Design Implementation
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Key Themes Abstraction: Focus on the essential, inherent aspects of an entity and ignoring the accidental properties Encapsulation or Information Hiding: Separate the external aspects of an object from the internal implementation details Combine Data and Behavior
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Sharing Emphasize object structure not procedural structure Synergy
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Hello World
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Comments The Java language supports three kinds of comments: /* text */ The compiler ignores everything from /* to */. /** documentation */ This indicates a documentation comment (doc comment, for short). The compiler ignores this kind of comment, just like it ignores comments that use /* and */. The JDK javadoc tool uses doc comments when preparing automatically generated documentation. For more information on javadoc, see the Java tool documentation. // text The compiler ignores everything from // to the end of the line.
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Applet
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HTML A Simple Program Here is the output of my program:
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