Getting Ready for Java version 1.1 28-Apr-19

What is Java? Java is currently a very popular language Java is a large, powerful language but it is not simple! It has syntax list all the C-family of languages: Variable names are case-sensitive Semi-colons after individual statements Curly braces around bunches of statements Comments start with // (or surrounded by /* and */) Compared to C++, Java is elegant

Syntax and semantics Syntax is the “grammar” of the language The syntax of Java is large, but finite Syntax must be absolutely correct The computer will point out every syntax error Error messages may be helpful or misleading Semantics is the “meaning” of your program Semantic errors cause your answers to be wrong You may or may not get error messages

Two aspects of Java Java has syntax and semantics This is where you begin It is possible to learn everything about Java’s syntax and semantics We will cover the basics of Java’s syntax and semantics Java also has “packages” Packages are sort of like vocabulary bundles To be good at Java, you need to learn many packages There are more Java packages than you can ever learn “packages” may also be called “libraries”

Versions of Java Java 1 - 1996 Java 2 Java 5 - 2005 Java 6 – Dec. 2005 Java 1.0: Original, not very good version Java 1.1: Greatly revised and improved Java 2 Java 1.2: Includes “Swing” Java 1.3: More new packages, no new syntax Java 1.4: Introduces the assert statement Java 5 - 2005 Java 1.5: Quite a bit of new syntax Java 6 – Dec. 2005 Runs faster, maybe other features

Vocabulary I JRE, Java Runtime Environment This is the software that allows you to run Java programs on your computer JDK, Java Development Kit (previously called SDK, System Development Kit) The software that allows you to create and run Java programs on your computer When you install the SDK, you get a JRE along with it IDE, Integrated Development Environment A tool that makes it easier to write programs

Vocabulary II – “Object orientation” Class A description of a bunch of data, and the subroutines which can manipulate that particular data Object A data structure in memory, and certain code that can change it Inheritance A way to reuse code in a class for a new class, with only small changes Interface The place where things touch each other The way that distinct things communicate Encapsulation The time-honored principle of information-hiding

Getting Ready If you plan to use your own computer: Download and install Java JDK 1.5 http://java.sun.com/javase/downloads/ Download the JDK, not the JRE Version 1.6 is also okay Download and install Eclipse 3.2.1 or newer http://www.eclipse.org/

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