CoreJava November 3, 2007

Free Java/J2ee Tutorials

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History of the Developement of Java
Started out in 1991 as Project Green focussed on O/S software for consumer electronic devices James Gosling recognized inadequacy of C++ and initiated development of Oak language Green went through several false starts before dissolving Small group decided to adapt Oak (later named Java) to a web technology — result was a new web browser, WebRunner (later named HotJava), operational in 1994 Paper on Oak byte codes presented by Gosling at Programming Language Design and Implementation (PLDI) conference in 1995
Introduction
Java is an object-oriented programming language developed by Sun Microsystems and released in 1995. Modelled after C++, the Java language was designed to be small, simple, and portable across platforms and operating systems, at both the source and binary level. One of the resons for Java’s popularity is its ability to bring executable content to the web.Java has only the necessary functionality needed to implement its feature set. It has omitted the features of C and C++ which have been considered to be “unsafe” pointer “forging” operator overloading static objects Memory is managed automatically, relieving the programmer from being responsible for freeing unused space There is no Java preprocessor – the program that you see is the same program that the Java compiler sees.

What is Java?

Java is an object-oriented programming language developed initially by James Gosling and colleagues at Sun Microsystems. The language, initially called Oak (named after the oak trees outside Gosling’s office), was intended to replace C++, although the feature set better resembles that of Objective C. Java should not be confused with JavaScript, which shares only the name and a similar C-like syntax. Sun Microsystems currently maintains and updates Java regularly.

Concepts of Oops

What Is an Object?

An object is a software bundle of related state and behavior. Software objects are often used to model the real-world objects that you find in everyday life. This lesson explains how state and behavior are represented within an object, introduces the concept of data encapsulation, and explains the benefits of designing your software in this manner.

What Is a Class?

A class is a blueprint or prototype from which objects are created. This section defines a class that models the state and behavior of a real-world object. It intentionally focuses on the basics, showing how even a simple class can cleanly model state and behavior.

What Is Inheritance?

Inheritance provides a powerful and natural mechanism for organizing and structuring your software. This section explains how classes inherit state and behavior from their superclasses, and explains how to derive one class from another using the simple syntax provided by the Java programming language.

What Is Encapsulation?

Encapsulation is a mechanism that binds together code and data it manipulates, and keeps both safe from outside interface and misuse. One way to think about encapsulation is as a protective wrapper that prevents code and data from being arbitrarily accessed by other code defined outside the wrapper.

What Is Polymorphism?

It is a feature that allows one interface to be used for general class of actions. The specific action is determined by the exact nature of the situation. More generally the concept of polymorphism is often expressed by the phrase “one interface, multiple methods”.