Misc

Case sensitivity

  • Java is case sensitive.

Version history

Java EE   Java SE   EJB   Servlets   JSP   JSTL   JSF   EL    JTA   JPA
-------   -------   ---   --------   ---   ----   ---   ---   ---   ---
  6         6       3.1     3.0      2.2    1.2   2.0   2.2   1.1   2.0
  5         5       3.0     2.5      2.1    1.2   1.2   1.1   1.1   1.0
  1.4       1.3     2.1     2.4      2.0    1.1   n/a   1.0   1.0   n/a
  1.3       1.2     2.0     2.3      1.2    1.0   n/a   n/a   1.0   n/a
  1.2       1.2     1.1     2.2      1.1    n/a   n/a   n/a   1.0   n/a

Java Platform, Standard Edition

  • Java SE 6 ... (Java 6 ...)
  • J2SE 5 (Java 5) [originally: J2SE 1.5]
  • J2SE 1.2 - 1.4 (Java 2)
  • JDK 1.0 - 1.1 (Java)

Java Platform, Enterprise Edition

  • Java EE 5 ... (Java 5 ...)
  • J2EE 1.2 - 1.4 (Java 2)

Type conversions


Safe, implicit conversions

  • byte -> short -> int -> long -> float -> double
  • char -> int

Installation

  • Java SE - Java Platform, Standard Edition
  • Ant - Java-based build tool
  • Maven - Similar to Ant (sometimes used in combination with Ant)
  • JBoss - Java EE server
  • Geronimo - Java EE server
  • Tomcat - JSP and servlet container
  • Jetty - JSP and servlet container
  • Java EE - Java System Application Server (GlassFish)
  • Java WSDP - Java Web Services Developer Pack

Sample linux installation

Directories
  • /usr/local/java/<jdk-version>
  • /usr/local/eclipse
  • /usr/local/tomcat
  • /usr/local/tomcat/common/lib   (MySQL Connector/J)
  • /usr/local/geronimo
Configuration files
  • /usr/local/tomcat/conf/server.xml (Tomcat)
  • /usr/local/tomcat/conf/web.xml (Tomcat)
  • /usr/local/geronimo/var/config/config.xml (Geronimo)
  • /usr/local/apache/conf/workers.properties (mod_jk)

GUI Toolkits

  • Widget toolkits

AWT

  • Abstract Windows Toolkit
  • AWT components are platform independent
  • AWT components are wrappers for platform-specific components
  • The appearance of GUI components varies based on the platform

Swing

  • Part of the Java Foundation Classes (JFC)
  • The appearance of GUI components is platform independent
  • Implented entirely in Java
  • Does not rely on platform-specific components

SWT

  • Standard Widget Toolkit
  • Third-generation widget toolkit for Java (with AWT and Swing being the first- and second-generation toolkits, respectively)
  • A richer, more-sophisticated version of AWT
  • Accesses platform-specific libraries through JNI

Terms


Byte-code

  • Compiled java code in a machine independent form. To be run in a Java Virtual Machine (JVM)

Java Virtual Machine

  • An interpreter that converts Java byte-code to native machine code at run-time, one instruction at a time

JIT compiler

  • Just-In-Time compiler
  • Translates byte-code into native machine code at run-time, as the program is loaded

Java class libraries

  • Libraries that can be called at run-time

JRE

  • Java Runtime Environment
  • JVM and class libraries

Java SE

  • Java Platform, Standard Edition
  • Previously called J2SE
  • Set of Java APIs for Java applications

Java EE

  • Java Platform, Enterprise Edition
  • Previously called J2EE
  • Set of Java APIs for enterprise Java applications
  • Includes an engine for servlets and JavaServer Pages (JSP)
  • Includes containers for Enterprise JavaBeans (EJB)

Java ME

  • Java Platform, Micro Edition
  • Previously called J2ME
  • Set of Java APIs for emedded Java programs

Java SDK

  • Java Software Development Kit
  • Previously called J2SDK
  • Development tools

JDK

  • Java Development Kit
  • Sun's Java SDK

JAR

  • Java Archive file
  • Zip file used to distribute a set of Java classes

WAR

  • Web application Archive
  • Zip file used to distribute a set of Java classes
  • Contains JSPs, HTML and related files, servlets, and tag libraries.
  • WEB-INF/web.xml  // Used for routing URL requests to servlets

 

 

Resources URL: 
notes/java/resources
Sources URL: 
notes/java/sources

See Also