Saturday, January 15, 2011

Free Book: Servlets and JavaServer Pages: The J2EE Technology Web Tier

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Servlets and JavaServer Pages: The J2EE Technology Web Tier

Addison-Wesley and Developmentor have provided with the entire book of Servlets and JSP the J2EE Web Tier for free download. Servlets and JSP the J2EE Web Tier is a book authored by Jayson Falkner and Kevin Jones about the latest in Servlets and JSP. The current version of the book covers Servlets 2.4, JSP 2.0, and the JSTL 1.0. Both Kevin and Jayson helped directly make the specifications and are proud to publish one of the first books covering the technologies. Servlets and JSP the J2EE Web Tier is comprehensive and covers everything you need to know about building Java web applications.

Who is This Book For?

Servlets and JSP the J2EE Web Tier is designed for developers of all levels. The book assumes a reader is familiar with HTML and the basics of Java. The book starts by covering how to installing a Servlet/JSP environment and what is in the JSP 2.0, Servlet 2.4, and JSTL 1.0 specifications. After discussion of the raw technologies the book focuses on practial use of them. The later chapters of the book cover topics such as state management, design patterns, internationalization support, multi-client design, Java database connectivity. At all possible places Jayson and Kevin try to share the millions of little things, both in the specs and not, that they have learned from being long-time Servlet and JSP developers.

If you are a new user this book is for you. It starts from the basics and covers everything up to the most advanced topics. If you are an experienced developer this book provides a reference for the Servlet 2.4, JSP 2.0, and JSTL 1.0 specifications and a good discussion of advanced design paterns and problem solving techniques. If you are management you are advised to buy multiple copies, this is a book which will be permanetly borrowed by employees.


Java is PASS BY VALUE. -

If you pass a primitive to a method, you don't get a reference to that primitive; you can't change it in that method. Pass by value.

If you pass an object reference, including an array, to a method, then the reference value is copied. Pass by value. Since the copied reference value is the same as the reference value that it was copied from, you can modify the state of the referenced object, but you can't alter the original reference in the method.

Get it right: you can modify the referenced object's state, but you can't modify the reference itself.

This is not because of magic elfs that defend the reference with life and limb. This is because Java is pass by value."

Tuesday, January 4, 2011

Java : A live language

Java is a language which can be understood only if it is learned by relating its different aspect with the real life.

Just for example, everything in the Universe is made by the almighty GOD, in the same way every class has directly or indirectly one father/super class i.e. java.lang.Object. If we create a singl class, internally it is extending the class java.lang.Object and getting the basic required nature from the super cosmic class 'Object'. If we create a sub-class 'B' of some class 'A' i.e., if B extends A then we see that indirectly class B is grandson of class Object as class A is the subclass of java.lang.Object and class B is the child/subclass of A. So, in a class hierarchy, every class will ultimately be the subclass of java.lang.Object class.

In real life every child has a single father, in the same way, every designed class in java has a single direct super class. So, as in real life, we see God, ...., Grandfather, father, son, grandson and so on...; in the similar way in java the tree structures looks alike i.e., java.lang.Object, custom class, subclass, subclass's subclass and so on. Here, we see that each class has a single father. I mean, java also supports the single inheritence i.e. a subclass can't be created by extending more then one class.

One person can have only one father. Suppose, the son inherits/learns music from his father. So, in java this is inheritence feature. a subclass can have inherited behaviour from its super class. Now suppose if the son who inherits playing music from his father, goes to learn computer from some other teacher then, the same person know two different things, one is music inherited from father and second computer from some other teacher. Thus, a person can add more ability in his life by getting knowledge from more then one people. Just the same concept here in java as interface. A subclass can inherit some feature from its super class and can implement the behaviours from more then one interface to make itself more able.