PPT02_Java_Basics - Java Programming Basics History of Java...

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Java Programming Basics History of Java 1991 Sun Microsystem’s project code-named “Green” To develop a programming language for consumer electronic devices Resulted in a C++ based language Sun called Oak (Oak was already being used) The name Java came during a break at a coffee shop History of Java Market for intelligent electronics was not developing rapidly Sun loses a major contract Sun saw potential to use Java to develop dynamic content web pages Introducing Java Released mid 1995 by Sun Microsystems Designed to be: A powerful, full-featured, OO development language Easy to learn Used on any platform Support development of applications for networked environments Java contains a full set of features Work with multiple platforms Access databases Client/Server capabilities Web enabled Helps eliminate common programming errors Catches data type mismatches Eliminates overwriting memory and corrupting data Powerful Class library Hundreds of prewritten classes Provide methods to accomplish various tasks OO Implements OO concepts Encourages good software design Reduces debugging and maintenance Simplicity Keywords Java has 48 keywords vs. Cobol or VB which have hundreds Have special meaning in the language Used in writing statements Portability Programs can be written and compiled once, then run on different platforms Important for internet applications (applets) Achieved by using: Bytecode Produced when a Java program is compiled Interpreter (Java Virtual Machine – JVM) Execution environment for bytecode on each platform Java Performance Page 1 of 12
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Java is considered an interpreted Language. Not as fast as compiled code, but faster than interpreted code. Sacrifices some performance for portability Just in Time (JIT) compilers Compile Java byte-codes into machine code at run time. Java Security Five Levels The Language The Compiler The Verifyer The ClassLoader The Security Manager Java Security Byte-code verification Sandbox Creates restrictions for untrusted code Prevents access to local resources by untrusted code Digital signatures Phases of Development Edit Compile (into byte-code) Load Verification Interpreter Java is Multithreaded Java provides support for multiple threads of execution. Basic to GUI’s Built-in language support for threads makes programming threads easier than C++ JAVA Applications vs Applets Application Stand alone programs that run on their own Applet A small application embedded in a web page Java Development Development environments Java Development Kit (JDK or SDK) Available free from Sun Web site: java.sun.com Includes: compiler, JVM, and classes Integrated Development Environments (IDEs) Sun’s Forte for Java Borland’s JBuilder BlueJ Eclipse – Open Source Java Beans Development Environment Do not use Microsoft’s Java Java Flavors Sun Page 2 of 12
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Consortium of companies (originally including Microsoft) Standard Java Definitions Microsoft Went there own way AFC (Application Foundation Classes) Microsoft’s answer to Sun’s GUI classes
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PPT02_Java_Basics - Java Programming Basics History of Java...

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