Describe Java Technology and the Java Development Environment

A Java Environment consists of the following

• An environment (JDK consists of development tools, compiler, debugger, class inspector and document generator)
• The language
• Java Application Programming Interface (API)
• Various Classes
• Java Runtime Environment (JRE)  

Java has to go through 5 phases into order to execute a java program

Editor	You create Java source code with a text editor such as vi (unix) or notepad (windows), the file will have a .java extension. you can use a IDE (integrated development Environment) such as JCreator, JEdit or eclipse.
Compiler	You use the command javac to compile the source code, this checks the syntax and translates the source code into bytecode, the language understood by the java virtual interpreter. A file with a .class extension is created.
Class Load	This phase loads the .class file into memory (the file can either be on disk or copied over a network) The .class file can be either a application program (run on your computer) or a applet (run within a web browser)
Bytecode Verifier	This phase checks that the bytecode meets Java's security restrictions, it enforces very strict rules to protect data on your computer.
Interpreter (Execute)	The last phase executes the bytecode one byte at a time using the JRE (Java Runtime Environment), thus performing the action you asked when to created the source code.

Identify key features of the Java language

For the exam you need to to have a understanding of the features of the Java programming language

Object Oriented - In Java, nearly everything is an Object (Java supports primitive data types). Java can be easily extended since it is based on the Object model.

Statically Typed - All variables have to be declared with a data type before using them

Platform Independent/Portability - When Java is compiled, it is not compiled into platform specific machine, rather into platform-independent byte code (Write Once and Run Anywhere - WORA). This byte code is distributed over the web and interpreted by the Virtual Machine (JVM) on whichever platform it is being run on.

Interpreted - Java byte code is translated on the fly to native machine instructions.

Simple to Learn - Java is designed to be easy to learn as you don't have to pre-allocate memory (use pointers). It is now the default language to learn in universities

Memory Management - Java uses a garabge collector to reclaim any memory that is not required

Secure - With Java's secure feature it enables to develop virus-free, tamper-free systems. Authentication techniques are based on public-key encryption.

Robust - Java makes an effort to eliminate error-prone situations by emphasizing mainly on compile time error and runtime checking.

Multithreaded - With Java's multithreaded feature it is possible to write programs that can perform many tasks simultaneously.

High Performance - With the use of Just-In-Time compilers, Java enables high performance..