ZachWingo

Purpose

The purpose of Unit 01 is to discuss the history and purpose of the Java Language. We discussed in detail the concept behind the Java VM with it’s pros and cons.

Concepts

• Compilation ─ in the Java language the code does not get compiled into the Operating Systems native language but rather it gets compiled into Byte Code.

• Byte Code ─ is code that can be run on the Java VM.
• Java VM ─ is short for Java Virtual Machine and acts as a virtual machine on which the Java byte code can run.
• Object Oriented Programming ─ is a programming paradigm based on the idea of creating objects. These objects contain all the code necessary to use them just like real world objects contain all the built in functionality needed to use them. This does not mean all possible features are available, but all the functionality available is designed to work on/with that specific object.
• Class ─ is the blueprint that defines the data and functionality that can operate on that data.
• Object ─ is an instance of a class. The class defines the object and one the object is create it contains everything define in it’s class.

Implication

The Java Language was created by Sun Microsystems in 1995 and promised “Write Once, Run Anywhere”. The idea was to create a Java Virtual Machine for each of the many different operating systems from appliances to servers. Java code would then be compiled into Byte Code that could then in turn run on any of the Java VM. This made code portable across many different platforms because developers would only need to write a single application and compile it once and it could then be run on any machine that had a Java VM.

The language was developed almost exclusively as an Object Oriented Programming Language. The purpose behind this type of programming is to model the real world in which objects contain all the necessary built-in functionality to use them. We define an Object by using what is called a Class which is essentially a blueprint for the object. The Class defines all the necessary data and function/methods to operate on that data. It’s not actually an Object until we actually create an instance of it which would be like actually building an automobile at a factory. It remains a concept on paper until it’s actually built and then it becomes an automobile. Objects are define in a class and remain nothing more than a concept until actually created.