Full HTML for

Basic foilset Java Tutorial - Summer 1997 Part 1:Introduction to Java Language

Given by Nancy J. McCracken,Geoffrey C. Fox at CEWES Tutorial, Classes SU/Jackson State on July 22-25 and Fall 97. Foils prepared 20 Sept 97
Outside Index Summary of Material

Overview including History and alpha versus production issues
Comparison of Java and Javascript
Overall Java Philosophy and Features including security etc.
And in Remaining Parts of Tutorial!!
  • Java Programming Language
  • Object Oriented and Class Structure
  • Exceptions
  • Applet Programming and Threads
  • Abstract Windowing Toolkit
  • Networking and I/O
  • Futures and HPCC Implications

Table of Contents for full HTML of Java Tutorial - Summer 1997 Part 1:Introduction to Java Language

Denote Foils where Image Critical
Denote Foils where Image has important information
Denote Foils where HTML is sufficient
denotes presence of Additional linked information which is greyed out if missing
1 Java Tutorial - Fall 97
Part 1: Introduction to Java Language
and Applets
http://www.npac.syr.edu/projects/tutorials/Java/
2 Abstract of Java Tutorial
3 What is Java in a NutShell?
4 Architecture of Java Applets
5 Overview -- What are Java applets in detail?
6 Running a Java Applet
7 Architecture of Java Applications
8 Java Applications in a Nutshell
9 The Simplest Java Application: Hello, World!
10 Java Applets
11 Applet Tag: Calling Applets from HTML - I
12 Applet Tag: Calling Applets from HTML - II
13 <param> Tags and Applets
14 The Simplest Java Applet: Hello, World!
15 Displaying your applet from a Web page.
16 Overview and History of Java Development
17 History of Java Language and Team
18 History of Java Language and Team until Dec. 95
19 JDK 1.0 -- The Java Development Kit!
20 JDK 1.1 -- Java grows!
21 Java Web Servers
22 Java vs. JavaScript
23 Comparison of Java and JavaScript -- I
24 Comparison of Java and JavaScript -- II
25 Overall Java Philosophy and Features
26 Some Key Java Features
27 Java Features -- It's Simple and Familiar!
28 Java Features -- It's Object-oriented
29 Java Features -- It's Architecture-Neutral
30 Java Features -- It's Portable
31 Java Features -- It's Somewhat Interpreted
32 Java Features -- It's Distributed
(and can support parallel computing)
33 Java Features -- It's Robust
34 Java Features -- It's (Hopefully) Secure
35 Java Features -- High Performance
36 Java Features -- It's Multithreaded
37 Java Features -- It's Dynamic
38 Sun's Comparison of Language Features I
39 Sun's Comparison of Language Features II
40 Java Books -- I
41 Java Books -- II
42 Java Beta Books -- III
43 Resources for the Java Programming Language

Outside Index Summary of Material

HTML version of Basic Foils prepared 20 Sept 97

Foil 1 Java Tutorial - Fall 97
Part 1: Introduction to Java Language
and Applets
http://www.npac.syr.edu/projects/tutorials/Java/

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Instructors: Geoffrey Fox
Nancy McCracken
Syracuse University
111 College Place
Syracuse
New York 13244-4100
HTML version of Basic Foils prepared 20 Sept 97

Foil 2 Abstract of Java Tutorial

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Overview including History of Java Development
Comparison of Java and Javascript
Overall Java Philosophy and Features including security etc.
Java Programming Language
Object Oriented and Class Structure
Exceptions
Applet Programming and Threads
Abstract Windowing Toolkit
Networking and I/O
Futures and HPCC Implications
HTML version of Basic Foils prepared 20 Sept 97

Foil 3 What is Java in a NutShell?

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
What is Java?
  • A simple, object oriented, distributed, interpreted, robust, safe, architechture neutral, portable, high performance, multithreaded, dynamic language.
Java is interesting because
  • It is both a general purpose object-oriented language along the lines of C++
  • and it is particularly designed to interface with Web pages and to enable distributed applications over the internet.
The Web is becoming the dominant software development arena; this will drive Java as the best supported, most widely taught language
  • Particularly good as a language for K-12 teaching
  • Even outside the web, e.g. in scientific computing, Java is as good and in some (modest) respects better than all other languages
HTML version of Basic Foils prepared 20 Sept 97

Foil 4 Architecture of Java Applets

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Browsers (HotJava, Netscape 2.0/3.0/4.0, Microsoft IE ...) supporting Java allow arbitrarily sophisticated dynamic multimedia applications inserts called Applets, written in Java, to be embedded in the regular HTML pages and activated on each exposure of a given page.
HTML version of Basic Foils prepared 20 Sept 97

Foil 5 Overview -- What are Java applets in detail?

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Applet constructs are implemented in terms of a
  • special HTML tag: <APPLET codebase="URL directory path" code="Java class file name" width=".." height=".." >
  • where the URL and class file name points to a chunk of server side software that is to be downloaded and executed at the client side on each presentation of a page containing this applet which executes in window specified in size by width and height in picxels.
HTML version of Basic Foils prepared 20 Sept 97

Foil 6 Running a Java Applet

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Steps to running a Java Applet:
  • 1. Write an HTML file that refers to the applet using the APPLET tag, described in later pages.
  • 2. If necessary, write the Java code and compile into class files
  • 3. Visit the HTML file with a web browser or with appletviewer.
Using a Browser
  • With a Java-enabled web browser, such as Netscape 2.0/3.0 or HotJava, you run an applet by "surfing" to a web page containing the APPLET tag.
Using appletviewer
  • When doing development, use appletviewer to run applets by specifying the HTML file on the command line:
    • appletviewer stock.html
HTML version of Basic Foils prepared 20 Sept 97

Foil 7 Architecture of Java Applications

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java applications are compiled and run on a machine just like any other general programming language such as C/C++. No web server or network are required although Java applications may also use network connections for distributed computing.
HTML version of Basic Foils prepared 20 Sept 97

Foil 8 Java Applications in a Nutshell

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
All Java programs are written into a file with a ".java" extension.
Applications are .java files with a main method which is excuted first.
How to compile and run a Java application:
  • Run the compiler on a .java file:
    • javac MyProgram.java
    • producing a file "MyProgram.class" of Java bytecodes
  • Run the interpreter on a .class file:
    • java MyProgram
    • which executes the bytecodes
The resources javac and java are part of JDK and are not in Netscape and so are not necessarily available on the same machine as your web server.
HTML version of Basic Foils prepared 20 Sept 97

Foil 9 The Simplest Java Application: Hello, World!

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Since Java is object-oriented, programs are organized into modules called classes, which may have data in variables and functions called methods.
HTML version of Basic Foils prepared 20 Sept 97

Foil 10 Java Applets

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java applets are classes written in Java which are intended not to run as stand-alone programs (as applications do) but as subprograms of a browser which is already managing a window.
Applets should NOT have main method but rather init, start, paint etc. for displaying on the browser window
The applet should be run through javac compiler getting a .class file as before: javac MyApplet.java
Also create an HTML file (say MyApplet.html) with an applet tag to MyApplet.class.
Two ways to run an applet:
  • If you have JDK on one's machine, one can run the applet with appletviewer
    • appletviewer MyApplet.html
  • Alternatively, run Netscape 2.0/3.0 or Internet Explorer essentially anywhere, point the browser at MyApplet.html, and applet is downloaded from the webserver and run by Java interpreter built into the browser. This requires that the .html and .class files are located in the document space of the web server.
This way we can compile on places with JDK installed but run almost anywhere!
HTML version of Basic Foils prepared 20 Sept 97

Foil 11 Applet Tag: Calling Applets from HTML - I

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Given the following HTML
  • <APPLET CODE="StockGraph.class"
    • CODEBASE="http://www.javasoft.com/applets/"
    • WIDTH=200 HEIGHT=200>
  • </APPLET>
Runs the "StockGraph.class" executable as an applet.
WIDTH and HEIGHT are attributes that are passed along to the applet.
If the optional CODEBASE attribute is provided, then load the executable image from the directory specified by CODEBASE.
  • Without the CODEBASE attribute, will look for StockGraph.class in the local server's hierarchy (relative to where the HTML was loaded)
  • With the CODEBASE attribute will look for StockGraph.class on the given http hierarchy.
Tag and attribute names are case insensitive.
HTML version of Basic Foils prepared 20 Sept 97

Foil 12 Applet Tag: Calling Applets from HTML - II

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
<APPLET CODE="StockGraph.class" WIDTH=200 HEIGHT=200
  • ALT="-- StockGraph Not Supported --"
  • NAME=SUNW ALIGN=top
  • VSPACE=5 HSPACE=5>
Put a bunch of text here to be displayed by browsers such as Netscape 2.0 on Windows 3.1 that do not support Java
</APPLET>
ALT specifies text to displayed if the browser understands the applet tag, but if unable to run applets.
NAME specifies the name of this instance of the applet; This will make it possible for applets on the same page to find and communicate with each other.
ALIGN specifies the alignment of the applet. The possible values are the same as those available in the IMG tag (top, middle, bottom, texttop, absmiddle, baseline, absbottom, left, right).
  • Align=top which aligns top of applet with top of tallest item in the line
  • Align=texttop which aligns top of applet with top of the tallest text in the line
VSPACE and HSPACE specifies the vertical and horizontal spacing in pixels, around the applet space.
HTML version of Basic Foils prepared 20 Sept 97

Foil 13 <param> Tags and Applets

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
The applet tag can be followed by parameters:
  • <applet . . . >
  • <param name=attributename1 value="attributevalue1" >
  • .......
  • <param name=attributenameN value="attributevalueN" >
  • </applet>
The Java program accesses this information by
  • String attribute;
  • attribute = getParameter("attributename1");
  • if( attribute == null )
  • attribute = yourdefaultvalue;
    • // null is Java way of saying unset
Typically this processing would be in init() method of Applet
HTML version of Basic Foils prepared 20 Sept 97

Foil 14 The Simplest Java Applet: Hello, World!

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java applets are part of the class hierarchy that can call methods to display on a screen (within the browser window). This example defines the public method paint in this class and calls a method drawString defined in the class Graphics.
HTML version of Basic Foils prepared 20 Sept 97

Foil 15 Displaying your applet from a Web page.

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
You should name the file with your applet name, HelloWorldApplet.java, run the compiler (javac), getting a bytecode file HelloWorldApplet.class, which you put in a web directory.
HTML version of Basic Foils prepared 20 Sept 97

Foil 16 Overview and History of Java Development

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
HTML version of Basic Foils prepared 20 Sept 97

Foil 17 History of Java Language and Team

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Starts in 1991 by Project Green --- a group in Sun that detaches from the main campus as a semi-autonomous task force focused on operating software for consumer electronic devices such as smart set-top boxes
Gosling (creator of Sun NeWS which had major conceptual impact both on current Java and Telescript models) realizes that C++ is not adequate and initiates development of a new language Oak, later renamed as Java.
A PDA (Personal Digital Assistant -- codename *7) based on Oak/Java ready in 1993. Green Team incorporates as FirstPerson, Inc.
*7 proposal to Time-Warner rejected in 1993. 3DO deal falls through in 1994. FirstPerson, Inc. dissolves.
Small group (~30 people, now Java Team) continues development and decides to adapt Oak as a Web technology.
HTML version of Basic Foils prepared 20 Sept 97

Foil 18 History of Java Language and Team until Dec. 95

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
An experimental web browser written in Java, called WebRunner and later renamed as HotJava, ready in 1994.
Alpha release of Java and browser HotJava April '95.
Netscape licences Java in May '95 and builds Java into Netscape 2.0 -- This confuses ownership and open-ness of Java
Beta JDK (Java Development Kit) published in summer/fall '95. It is better software but lower functionality than Alpha.
First alpha Java books appear in fall '95 such as a popular overview by SAMS and technical book "Java!" by Tim Ritchey, edited by New Riders.
Dec 4 1995 Business Week cover story on "Software Revolution --- The Web Changes Everything" exposes Java as a breakthrough force in the expanding Web/Internet. Also points out that "Java as a business" is yet to be defined.
In next week, SGI IBM Adobe Macromedia and finally Microsoft adopt/license Java. Java goes into open standards process and is adopted by Web community.
HTML version of Basic Foils prepared 20 Sept 97

Foil 19 JDK 1.0 -- The Java Development Kit!

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
The beta version of Java, Version 1.0 of JDK released January 96 by JavaSoft.
JDK 1.0 becomes the Internet standard and so compatible with ongoing Java implementations by all licensees, most notably Netscape and Microsoft. Beta/1.0 JDK includes:
  • Java Compiler (.java to .class) for Sun Solaris and Windows NT/95 avaliable as .class itself (Javac written in Java) but no source
  • Java source for the foundation classes (modified and incompatible with alpha)
  • appletviewer to run/preview applets
  • Source code for the interpreter
HTML version of Basic Foils prepared 20 Sept 97

Foil 20 JDK 1.1 -- Java grows!

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
A substantial new version of Java released March 97 by JavaSoft.
This release includes many developments both by Sun and by partner companies such as IBM. There are minimal changes to the language - primarily development of new classes to support enterprise computing.
We are currently (Sept. 97) in a transitory situation where a few preleased features of JDK 1.1 such as the Java DataBase Connection (JDBC) are supported by the primary browser Netscape 3.0 and Internet Explorer 3.0, but most JDK 1.1 features are not yet supported in commonly available browsers, except for HotJava.
  • Netscape4.0 and Internet Explorer 4.0 do suport JDK 1.1
http://www.javasoft.com/products/jdk/1.1
HTML version of Basic Foils prepared 20 Sept 97

Foil 21 Java Web Servers

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Originally, the Java Interpreter was incorporated into browsers such as those from Netscape and Microsoft, but the Web server remained a standard one.
Now Web servers are being developed in Java itself. This leads to more natural integration of the use of Java applets on the Web browsers and Java applications running on the Web server machine.
  • Java WebServer from Sun - http://jserv.javasoft.com/ - This web server is developed following new Java Server API, which allows for security and encryption servers. WebServer will run Java applications, called servlets, on the server side similarly to CGI scripts.
  • Jigsaw from the W3 Consortium - http://www.w3.org/pub/WWW/Jigsaw - This web server had the most services but is currently being rewritten so that the model for running Java on the server side will be JavaBeans.
HTML version of Basic Foils prepared 20 Sept 97

Foil 22 Java vs. JavaScript

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
HTML version of Basic Foils prepared 20 Sept 97

Foil 23 Comparison of Java and JavaScript -- I

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Netscape renames Livescript as Javascript and this is an interesting variant of Java which is fully interpreted (code can be included directly in HTML file)-- use for overall customization of client
Use Java for detailed programming and JavaScript for overall integration of client interface and system
JavaScript: Interpreted by client and NOT compiled
Java: Compiled on Server before execution on client
  • Note both are reasonably "pure" C/C++ like languages and do NOT have useful sh/awk text and system enhancements of Perl(5)
JavaScript: Object based -- no classes or inheritance -- built in extensible objects
Java: Object-oriented. Programs consist of object classes with inheritance
HTML version of Basic Foils prepared 20 Sept 97

Foil 24 Comparison of Java and JavaScript -- II

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
JavaScript: Integrated with HTML as embedded ascii but of course HTML looks rather irrelevant at times!
Java: Applets distinct from HTML but invoked from HTML Pages
JavaScript: do not declare variables' datatypes -- Loose typing
Java: MUST declare variables' datatypes -- Strong typing
JavaScript -- Dynamic Binding -- object references computed at runtime
Java -- Static Binding -- object references must exist at compile time
Java and JavaScript are secure and cannot write to disk
JavaScript has most user interface features of Java (such as buttons and frames), except not mouse interactions like "dragging".
HTML version of Basic Foils prepared 20 Sept 97

Foil 25 Overall Java Philosophy and Features

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
HTML version of Basic Foils prepared 20 Sept 97

Foil 26 Some Key Java Features

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Document The Java: A White Paper by Sun Microsystems -- October 1995 draft by James Gosling and Henry McGilton -- enumerates the original design of Java:
Simple and Familiar
Object-oriented
Architecture-neutral
Portable
Somewhat Interpreted
Distributed
Robust
Secure
High performance
Multi Threaded
Dynamic
HTML version of Basic Foils prepared 20 Sept 97

Foil 27 Java Features -- It's Simple and Familiar!

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java omits several rarely used, poorly understood and confusing features of C++ including operator overloading, multiple inheritance, pointers and automatic type coercions.
It adds automatic garbage collection which makes dynamic programming easier in Java than in C or C++.
  • No more mallocs!
It also adds 'Interface' construct, similar to Objective C concept, which often compensates for the lack of multiple inheritance by allowing method calling syntax to be "inherited".
The resulting language is familiar as it looks like C++ but is simpler and hence easier to program in.
It also results in a much smaller kernel which is suitable for planned Java ports to consumer electronic devices. Base (alpha) interpreter is ~40Kb, libraries and threads add additional 175Kb.
HTML version of Basic Foils prepared 20 Sept 97

Foil 28 Java Features -- It's Object-oriented

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java model can be viewed as a C++ subset, with some dynamic elements inherited from Objective-C (method overloading, garbage collection).
Structures, Unions and Functions are absorbed into data and methods of Java classes -- Java is Simple!
The strength of Java object-oriented model is not is sophistication but in simplicity and the extensive class library associated with the system (some 250 public classes were released in both alpha and beta).
Java class plays also a role of a communication atom in the Web embedding model. Applet classes identify themselves by names in the HTML applet tag. Applet downloads other classes, present in the applet source. Hence, the Java class names play the role of addressing mode for the distributed Java code database.
HTML version of Basic Foils prepared 20 Sept 97

Foil 29 Java Features -- It's Architecture-Neutral

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
C/C++ programming in a heterogeneous network environment requires use and compatibility across several vendor platforms and the corresponding compilers. This problem is solved in Java by designing platform-independent binary representation called Java bytecode (or opcode).
Java compiler (written in Java and platform-independent) reads Java source and generates Java bytecode. These bytecodes are shipped to client machines upon browser requests.
Each client machine must run Java interpreter which performs runtime execution of Java bytecodes. Java interpreter is written in POSIX compliant ANSI C and needs to be ported to and conventionally compiled (once) on each individual platform.
Once the interpreter is ported, application developers don't need to worry at all about platform specificity and differences between native compilers.
HTML version of Basic Foils prepared 20 Sept 97

Foil 30 Java Features -- It's Portable

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java language offers a uniform abstract (virtual) machine model which is identical for all platforms.
SUN owns the Java Virtual Machine (see online report) -- it is universal while classes can be added by any user
Unlike in C/C++ where various integers match the architecture of a physical machine at hand, Java byte, char short, int and long are always of the same size, equal to 8, 16, 16(unicode), 32 and 64 bits, respectively.
  • No header files, preprocessors,#define etc.
  • floating point is always IEEE 754
Differences between vendor specific windowing environments (X Windows, MS Windows, Macintosh) are removed in terms of the Abstract Windowing Toolkit (AWT) metaphor.
AWT is given by ~60 Java classes (alpha) which offer a universal GUI programming model, portable between UNIX, PC and Mac, and translated automatically to native windowing systems on individual platforms by Java interpreters.
HTML version of Basic Foils prepared 20 Sept 97

Foil 31 Java Features -- It's Somewhat Interpreted

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java represents a compromise between fully compiled (like C/C++) and fully interpreted (like Smalltalk or Perl) models.
Java "compiler" produces a binary bytecode output which is portable and much smaller than the real binary for a specific machine (Typical bytecode size is of order of the original source code, within a factor of 2).
Java "interpreter" executes this bytecode and is therefore less dynamic than e.g. Perl interpreter (which performs an equivalent bytecode construction internally and on-the-fly when reading the program source).
In general, the compilation process is: a) time consuming and b) platform specific. Hence, interpreters are built and used to facilitate a) rapid prototyping and/or b) portability. Java model is focused on platform independence but the development throughput is also reasonable since the Java compiler is fast and generates compact bytecode output.
HTML version of Basic Foils prepared 20 Sept 97

Foil 32 Java Features -- It's Distributed
(and can support parallel computing)

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Popular TCP/IP based protocols such as FTP or HTTP are supported in terms of network protocol classes.
  • This implements Java plus message passing and immediately supports various forms of distributed processing.
  • New protocols, such as PVM and MPI, can be added and dynamically installed.
  • Parallel computing can be built on top of these base classes.
Distributed computing model of Java is mainly client-server, with Java compiler preparing the opcodes at the server side, and Java interpreter executing it at the client side.
HTML version of Basic Foils prepared 20 Sept 97

Foil 33 Java Features -- It's Robust

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java enforces compiler-time type checking and eliminates this way some error prone constructs of C/C++.
Pointer arithmetic is fully eliminated which allows e.g. for runtime checking of array subscripts and enforces security of the Java model.
Explicit declarations are always required, i.e. C-style implicit declarations are abandoned. This allows the Java complier to perform early error detection.
Rapid prototyping in Java is less natural than in JavaScript,Lisp, Tcl, Smalltalk or Perl, but the software quality assurance of Java is higher than in these more dynamic and 'forgiving' languages.
HTML version of Basic Foils prepared 20 Sept 97

Foil 34 Java Features -- It's (Hopefully) Secure

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java bytecodes are shipped across the network and executed on client machines. Security is therefore a critical issue and strongly enforced in Java.
  • Java contains its own networking classes which are designed to be secure
Modifications of the C++ model such as eliminating pointer arithmetic and coercion were dictated mainly by the security requirements.
Most viruses are based on acquiring access to private/protected sectors of computer memory which is impossible in Java.
Java opcodes are executed at the client side by Java interpreter which operates exclusively on the virtual memory. Hence, unless there are security bugs in the Java interpreter itself, the model is safe and users cannot create security holes by incorrectly or maliciously written applets.
The bytecodes sent across network are verified at the client which prevents evil/corrupted classes from causing problems
HTML version of Basic Foils prepared 20 Sept 97

Foil 35 Java Features -- High Performance

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java interpreter performs on-the-fly runtime execution of the Java bytecodes which results typically in a satisfactory performance.
  • NOT true in initial software which is often 100 times slower than C
  • performance is improved in new "just-in-time" interpreters, which saves code for repeated sections to provide compiled code efficiency after first execution
Support for generating native machine code out of Java bytecodes, viewed as intermediate compiler form, is also provided and useful for performance demanding applications.
The performance of the machine code, generated from Java bytecodes, is comparable to that offered by typical C/C++ compilers on the same platform.
Several of these concepts are in fact similar as in the OSF/ANDF project. Using ANDF terminology, we would call Java compiler a 'producer', and the machine code generator discussed here, an 'installer'. Default Java working mode doesn't use installers but directly interprets the intermediate form (this mode is supported in ANDF by GAI -- Generalized ANDF Interpreter).
Java/HotJava system implements ANDF concepts for the Java language.
HTML version of Basic Foils prepared 20 Sept 97

Foil 36 Java Features -- It's Multithreaded

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java model offers preemptive multithreading, implemented in terms of the Thread class. Thread methods offer a set of synchronization primitives based on monitor and conditional variable paradigm by C.A.R. Hoare. Java threads inherit some features from the pioneering Cedar/Mesa System by Xerox Park that gave birth to Macintosh and object-oriented programming.
A typical use of Java multithreading in applet programming is to have several independent but related simulations (e.g. various sorting algorithms), running concurrently in an applet window. Multithreading is also used internally by the browser to handle multiple document dynamics.
Another interesting application domain are multi-HotJava environments to come such as collaboratory or gaming.
Java threads don't have built-in point-to-point communication primitives. Various thread communication environments can be provided by coupling the thread and network protocol objects.
HTML version of Basic Foils prepared 20 Sept 97

Foil 37 Java Features -- It's Dynamic

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Java model is more dynamic than C++ and closer to Smalltalk or Perl.
Subclasses don't need to to be recompiled after superclass implementation is updated.
C++ has "fragile superclass" problem where must recompile children if change anything (method/instance variable) in a superclass or referenced class -- Java resolves references at runtime and avoids this.
Classes have runtime representation (implemented in terms of the Class class) which allows one to look up type of a given object instance at runtime (in C cannot know if pointer is to integer or browser!)
HTML version of Basic Foils prepared 20 Sept 97

Foil 38 Sun's Comparison of Language Features I

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
HTML version of Basic Foils prepared 20 Sept 97

Foil 39 Sun's Comparison of Language Features II

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
HTML version of Basic Foils prepared 20 Sept 97

Foil 40 Java Books -- I

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
Teach Yourself Java in 21 Days, 2nd ed., by Laura Lemay and Charles L. Perkins, Sams.net Publishing, is a "how-to" book at the intermediate programming level, greatly expanded from the original edition.
Java in a Nutshell, by David Flanagan, is the language reference book in the familiar O'Reilly series. The 2nd edition of this book is now out - it omits many examples from the first edition to make room for large section on JDK 1.1 - currently best book reference. Both 1st and 2nd edition are quite useful.
Java, How to Program, by Deitel and Deitel, Prentice-Hall, starts with beginning programming concepts and progresses rapidly through Java language. It has the most programming exercises and also has companion teaching multimedia books.
HTML version of Basic Foils prepared 20 Sept 97

Foil 41 Java Books -- II

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
The Java Programming Language, by Ken Arnold and James Gosling, Addison-Wesley, May 1996, has lots of details on the language basics for intermediate and advanced programmers. It covers threads and i/o packages, but not applets or windowing packages.
  • All serious computer scientists should read to understand fundamentals
Java Primer Plus, supercharging Web applications with the Java programming language, by Paul M. Tyma, Gabriel Torok, and Troy Downing, Sams.net, doesn't assume a lot of programming background, has chatty explanations and still covers lots of programming detail.
HTML version of Basic Foils prepared 20 Sept 97

Foil 42 Java Beta Books -- III

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
There are now many books in the Java Series from SunSoft Press, Prentice-Hall. Here are the first five:
  • instant Java*, by John A. Pew, contains multimedia and animation applets for HTML authors. This is not a programming book.
  • Java by example, by Jerry R. Jackson and Alan L. McClellan, covers all key features with examples, but not as much detail about the language.
  • just Java, by Peter van der Linden, for intermediate programmers, gives good explanations of key features without going into detail.
  • core Java, by Gary Cornell and Cay S. Horstmann, offers detailed coverage of the language and packages for advanced programmers.
  • graphic Java, by Gary McClellan, gives more details on windowing and user interface and includes new classes (not in originial Java release) for such things as "rubberbanding".
* this title is great, but what happened to "express Java", "Percolating through Java", and "Java for Drips"?
HTML version of Basic Foils prepared 20 Sept 97

Foil 43 Resources for the Java Programming Language

From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. *
Full HTML Index
The original resource was the The Java Language Specification by Sun Microsystems, Inc., March 1995 updated to October 1995 but superceded by Gosling and Arnold Book
  • Addison Wesley has several other fundamental Java books on Application Programming Interface and Language Specification and Virtual Machine (by end of summer 1996)
http://www.javasoft.com web site has plenty of references including
  • Tutorial: http://www.javasoft.com/books/Series/Tutorial/index.html
  • Books:http://www.javasoft.com/java.sun.com/aboutJavaSoft/book-news.html
  • Collection of Applets: http://www.gamelan.com
Most of the books cited earlier have CDROM's with examples and the JDK.
© on Sun Oct 12 1997