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Introduction
What is/isn't Java?
 | IS
 | a simple, object-oriented, distributed, interpreted, robust,
secure, architecture-neutral, portable, high-performance,
multithreaded, dynamic, "buzzword-compliant",
general-purpose programming language |
| "C++ done right" |
|
| IS NOT
| "real-time" |
| for Games like DOOM or Quake |
|
Java History
| Origins - Oak project and conversion to WWW
http://java.sun.com/features/1998/05/birthday.html |
| JavaScript vs Java
| JavaScript is...
 | A quick and dirty scripting language for automation
(loosely typed) |
| Object-Based (not Object-Oriented) |
| Depends on a Web Browser for much infrastructure support
and security |
| "Standardized" from Netscape JavaScript and
Microsoft JScript (ECMA 262 - ECMAScript)
|
|
| Java is...
| Full-fledged programming language (strictly typed) |
| Object-Oriented (has strict notions of inheritance,
visibility) |
| Comes with own VM as support and security |
| Not Standardized (Controlled by Sun, who is trying to
"Standardize" yet remain in control of its
future) |
|
|
| JDK 1.0x, 1.1, 2.0 |
|
Version |
Highlights |
|
1.0 |
Debute in 1995 |
| 1.02 |
Bug fixes of
1.0. AWT Event Model introduced |
| 1.1 |
AWT Event Model fixed |
| 1.2 |
Java2 platform
| javax Extensions |
| JFC (Swing, Java2D, Accessibility) |
| Collections API |
| More tools in java.util, more control over GC |
|
| 1.3 |
|
| 100% "Pure Java" and legal implications
| Condensed Version
| Microsoft licenses Java Technology from Sun |
| Microsoft implements Java and adds own Java language
extensions and punts JNI for J/Direct |
| Sun sues Microsoft for attempting to fragment or subvert
the Java "platform" (via copyright infringment) |
|
| Ramifications taken
| Microsoft has to add support for JNI |
| VisualJ++ has to warn users if they enable Microsoft's
extensions |
| VisualJ++ has to default to disabling Microsoft's
extensions |
|
| Clean Room Java Technology
| HP Chai |
| Travsvirtual Kaffe |
| Open Source Japhar |
|
|
| Specialized versions
| Java2 Platform, Enterprise Edition |
| Consumer and Embedded Technologies
| Java2 Platform, Micro Edition |
| Jini |
| PersonalJava |
| EmbeddedJava |
| Java Card |
| Java Phone |
| Java TV |
| ... The list goes on and on... |
|
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Applet Example
| Java and HTML |
Useful General Syntax
<APPLET
CODE="applet-class" WIDTH=width-in-pixels
HEIGHT=height-in-pixels [ARCHIVE="jar-filename"]
[CODEBASE="where-is-the-root-location-of-the-applet"]
[ALIGN="left,right,top,bottom,center..."]
[ALT="Text-browser-displays-if-applet-can't-be-run]
...other applet options
>
[<PARAM NAME=applet-parameter-1 VALUE=value1]
[<PARAM NAME=applet-parameter-2 VALUE=value2]
...
HTML that browser displays if applet did not run
</APPLET>
| Must specify
| CODE
| where is the applet class located? |
| MyApplet[.class] |
|
| WIDTH, HEIGHT
| how big an area in the browser does the applet get? |
|
|
| Useful
| CODEBASE
| Applets can depend on this to load images using
relative URL |
|
| ALT
| Be nice to surfers that don't turn on Java! |
|
| ALIGN
| How the applet is positioned within the browser |
|
| ARCHIVE
| If applet is in a JAR file, specify where the JAR
file is
|
|
|
| Applet embedded in HTML Example
| HelloWorldApplet.java |
| HelloWorldApplet.html |
|
| Differentiate between Applet and Application
| Applets and Application trade off between portability and
security
| Applets are portable code from anywhere, hence untrusted
and highly restricted |
| Application are local, hence inherently trusted and
loosely restricted |
|
| Later on, we'll turn our previous "Hello World" class
into one that can be both an applet and application (with
restrictions) |
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Java Architecture Overview
Language (Details later)
| Features
| "Write once, run anywhere"
| Java Source code compiles to intermediate Jave Bytecode |
| Java Bytecode targets the Java Virtual Machine (JVM),
not Native Machine |
| Java Bytecode runs anywhere the JVM runs |
|
| Security
| Java Bytecode checked/verified before being executed in
the JVM |
|
|
| Java Basics
| Object Oriented
| Java consists of Classes, Fields, Methods |
|
| Similar to C++ in semantics and syntax |
| Easier to use; harder to shoot yourself |
| Fewer grungy details |
|
| Sample Java Code
| Using our earlier applet... upgrade it |
| How to make a class that's both an Application and Applet
depending on context
| HelloWorldApplet2.html |
| HelloWorldApplet2.java |
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API (Details later)
| API vs Java
| Java - the programming language |
| API - Interfaces for programmers to use, all written for and in
Java
| Jini, JavaOS - "Other" API |
| Servlet, JavaBeans Activation Framework, JavaMail -
"Other" API that extend the core Java API |
| Collection, Java Foundation Classes (Swing, Java2D,
Accessibility) - "Other" API that extend and
is distributed with the core Java API |
|
|
Using Java
JDK versions
| Browse the Javasoft website for the most recent JDK/Java platform
alignments! http://www.javasoft.com/products |
| Standard Tools
| java - the interpreter
| Given a class, java tries to run the method that has the
signature
public static void main(String[]) |
| The class is specified by name and also package path if
it exists |
|
| javac - the compiler |
| appletviewer - test applets |
| javadoc - HTML Documentation generator |
| jdb - debugger |
| others - jar, javah, javap, rmic |
| applet/document viewer - Netscape, IE, HotJava, etc. |
|
Other Tools
| IDEs
| Advantages over bare-bones JDK
| No makefiles and dependencies to maintain |
| More powerful and visually intuitive debugging
| Jump in/out/forward/backward in code |
| Set/unset breakpoints |
|
| Advanced Debugging support for Server/Client like RMI |
| Creature Comforts
| Syntax Coloring |
| Autocompletion |
| Easy access to help |
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| Comercial Products
| Symantec Visual Cafe |
| Microsoft J++ |
| IBM VisualAge |
| Sun JavaStudio and JavaWorkshop |
|
| Free Products
| Borland JBuilder |
| Kawa Java IDE |
| Emacs JDE |
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| Others
| Free VMs - Japhar, KVM |
| Free APIs - NinjaRMI, GNU classpath |
| alternative compiler - jikes (from IBM) |
| jasmin, decompilers, obfuscators |
| Performance enhancers such as Mocha, JIT, Hotspot |
| Language extensions: pizza (GJ), polyj |
| Embedded systems tools: Jump |
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Books
| Favorites
| Flanagan. Java in a Nutshell, Third Edition |
| Horstmann, Cornell. Core Java 2, Volume 1 |
| Geary. Graphic Java 2, Mastering the JFC Vol 1 (AWT), Vol 2
(Swing) |
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| Official Sun Introductory Books
| Campione and Walrath, The Java Tutorial, Second Edition |
| Kanerva, The Java FAQ |
| Arnold and Gosling. The Java Programming Language, Second
Edition |
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| Official Sun Specifications
| Gosling and Steele, The Java Language Specification |
| Lindholm, Yellin. The Java Virtual Machine Specification, Second
Edition |
| Chan, Lee, Kramer. The Java Class Libraries, Second Edition |
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Links
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