Java platform and free software — Presentation Transcript
Java Platform & Free Software
José María Casanova Crespo
Master on Free Software
Introduction Agenda
● Basic ideas
● OO programming and basic syntax.
● History and Versions
● License
● Java Community
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Basic Ideas
● Java ...
– is an object oriented programming language
– programs are compiled once and executed
everywhere (bytecode and Virtual Machine)
– syntax is derived from C++
– is supposed to be platform independent
– implements automatic memory management
– platform is almost Free Software ;-)
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Remembering Syntax
Practice
● Create a class Animal that Sleeps.
● Create a Main class for playing with animals.
● Create a Subclass Pet that has a Name and
Owner that is a Person.
● Re-factor it to define Pet and Animal as abstract
classes and create Dog and Elephant
● Overwrite methods and make possible not
animal pets (Interfaces)
● Introduce the use of packages
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The Father: James Gosling
● 1955, Born in Calgary
● 1983, PhD at Carnegie
Mellon University.
● 1984, joins SUN
Microsystems.
● 1991, invents Java
Programing Language
● 2006, he shaved for the
first time in decades.
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The early years
● Created in June 1991
● Initially called Oak ....
– ... later called Green....
● ... finally renamed to JAVA
● SUN launched JAVA on May 23, 1995
● More info:
– http://java.sun.com/features/1998/05/birthday.html
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Oak
● Oak goals:
– Platform independent
– Extremely reliable
– Compact
● Target market: Interactive TV and PDAs
● But in 1993 SUN changed the target
because of Internet.
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Java Versions
● JDK 1.0 (1995)
– 8 packages, 212 classes.
– Included in Netscape 2.0-4.0
– Other companies licensed Java
● JDK 1.1 (1997)
– 23 packages, 504 classes
– inner classes,improved JVM, SWING
– MS develops a VM for IE
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Java Versions
● JDK 1.2 (2000), known as JAVA2)
– 59 packages, 1520 classes
– Java Foundation Classes (SWING) included in
the core.
– Collections: support for lists, sets, hashmaps.
– Code and Tools distributed as the SDK
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Java Versions
● JAVA 1.5 (2004) renamed to JAVA5
– Generics
– Faster startup and improved memory usage
– Improved multithreading features
● JAVA 6
– new desktop related features
– simplified GUI development
– integrated with NetBeans 5.5
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Multiple Platforms
●
– Java Enterprise Edition (JAVA EE)
– Java Micro Edition (JAVA ME)
– Java Standard Edition (JAVA SE)
● JRE vs JDK
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Java License Questions
● Look for the current License of JDK, go for
downloading.
● Which is the current state of Java as
FLOSS?
● Operating System Distributor License for
Java (DLJ) ... what is it?
● Lets review History ....
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The JAVA TRAP
● Richard Stallman Apr 12, 2004
● http://www.gnu.org/philosophy/java-trap.html
● Nov 15, 2006
● SUN “releases Java” under GPL
● http://www.sun.com/2006-1113/feature/story.jsp
– Hotspot VM, javac
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The Classpath Exception (1/2)
Linking this library statically or dynamically with
other modules is making a combined work based
on this library. Thus, the terms and conditions of
the GNU General Public License cover the whole
combination.
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The Classpath Exception (2/2)
As a special exception, the copyright holders of this library
give you permission to link this library with independent
modules to produce an executable, regardless of the license
terms of these independent modules, and to copy and
distribute the resulting executable under terms of your choice,
provided that you also meet, for each linked independent
module, the terms and conditions of the license of that
module. An independent module is a module which is not
derived from or based on this library. If you modify this library,
you may extend this exception to your version of the library,
but you are not obligated to do so. If you do not wish to do so,
delete this exception statement from your version.
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Current State
● Several Open Source projects
– Java SE -> OpenJDK
– Java ME -> Mobile & Embedded (PhoneME)
– Java EE -> Glass Fish
● http://www.sun.com/software/opensource/java/index.jsp
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JAVA Communities
● APACHE Foundation
– JAVA related projects (JAKARTA)
● http://jakarta.apache.org
● Ant, Tomcat, Structs, Lucene, ...
● Lets review the website.
● Open Source in Java
– Open source directory about Java Apps.
● http://java-source.net/
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Java Community Process
● http://www.jcp.org/en/home/index
– Introduced in 1998
– an open, participative process to develop and
revise the Java™ technology specifications
– define reference implementations and test
suites
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ECLIPSE
● http://www.eclipse.org
● Version 3.3 called Europa (Jupiter moon)
● written in Java.
● lots of plug-ins for different languages.
● Eclipse Java Development Tools,
incremental Java Compiler, visual editor
interfaces.
● Eclipse Public License
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NETBEANS
● http://www.netbeans.org
● Directly from SUN Microsystems
● NetBeans 6 is the last version
● Lately supporting more languages
● Oct 2007, CDCL and GPLv2 License
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JDEE EMACS
● http://jdee.sourceforge.net/
– JDEE menu with compile, run, debug, build, browse, project,
and help commands
– syntax coloring
– auto indentation
– compile error to source links
– source-level debugging
– source code browsing
– make file support
– automatic code generation
– Java source interpreter (Pat Neimeyer's BeanShell)
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Compiling game
● Working in pairs based in knowledge in
each IDE platform.
● Choose a JAVA not web based project in
Source Forge (the simpler the easier)
● Compile it and execute
● Analyze the possibilities with Source Code
Repositories (SVN,CVS)
● Which is the better IDE ?
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