CSCI 224

Introduction to Java Programming

Course Objectives

Learn the Java programming language: Syntax, Idioms Patterns, Styles

Become comfortable with OOP Learning to think in objects

Learn the essentials of the Java class library And how to learn about other parts when you

need them

Writing Code

It is not enough to write code that works.

It is important to write code that is also Legible, Maintainable,

Reusable, Fast and Efficient

Java

Sun defines Java as a: “…simple, object-oriented, network

savvy, interpreted, robust, secure, architecture-neutral, portable, high-performance, multi-threaded, dynamic language.”

What is Java?

History of Java First started in 1990 as Sun’s Green project

Digitally controlled consumer devices identified as trend

Trend did not grow as expected 1994 – WWW popularity Netscape packaged Java within browser

- MS Explorer followed suit Success ultimately depended on e-commerce

What is Java

Java is a high level,third generation programming language

Compared to other languages it is most similar to C and shares much of the syntax Unlike C++ Java is not a superset of C

and substantial amounts of C code would need to be reworked to become a Java program

Java is :

A Platform Simple Object-Oriented Platform independent Safe High Performance Multi-Threaded Garbage Collected

Platform

Three elements to Java The programing language The compiler The Java interpreter

The Java compiler creates byte code and not code native to particular platform. The result is that the JVM the runtime machine interprets this code on the fly and translates it to the machine.

Simple

Java is designed to be easy to write. Not a lot of special tricks to confuse

beginners Memory allocation and deallocation are

handled automatically. Syntax is straight forward in most

situations.

Object Oriented

The core concept of Java Everything is an object. Huge libraries of objects are available.

Learning to use the API is essential

Platform independent

The Java byte code is never really executed on the host machine.

Each JRE / JVM does all the work of interfacing with the OS and machine.

Also eliminates having to deal with variations in platform architecture Integer is always four bytes.

Safe

Java was designed from the ground up to allow for execution across a network.

Applets – executed with set limitations on what they can do to within your system. Essentially they run in a sandbox.

High Performance

The Java byte code compiles on the fly with speeds that rival the C++ compiler.

Multi-Threaded

Java is inherently multi-threaded allowing a single program to execute different processes independently and continuously.

The is a cost to this for the programmer. Just as in C pointer arithmetic can be hard to debug, debugging threads is a challenge.

Garbage Collection

There is no need to explicitely allocate or de-allocate memory in Java.

No need to write destructor methods. The JRE handles the trash.

Practical

What do you need to run Java. JDK – Java developer's Kit. JRE – Java Runtime Enviroment SDK – Java Software Development Kit

IDEs Several development tools exist.

The most basic thing you need is Notepad or any text editor to write the java source files.

Jbuilder, Sun's One Studio , JCreator, Forte and Eclipse are just a few.

Development Tools

1995 – First JDK released by Sun (1.0) Very limited

JDK 1.1 released Limited GUI creation

1.2 released Major change – Swing components Java 2 SDK release 1.2 Better known as Java 2

Most current version: 1.5

Development Tools

Java 2 Editions Java 2 Platform, Standard Edition Java 2 Platform, Enterprise Edition Java 2 Platform, Micro Edition

Java Programs

Applets Java program running within client Web

browser Servlet

Java program running on a server Can ‘cooperate’ with applet or

application Application

Standalone program