by Dinesh Thakur

What is http: HTTP full form HyperText Transfer Protocol used mainly to access data on the World Wide Web. HTTP is a Server and Client communication Protocol, which is primarily set of rules for formating and transferring webpage data (text, images, video and Multimedia files) over the world wide web. This is the Protocol used to create communication between Web Servers and Web Users. HTTP is an application layer Protocol that works on the top of the TCP/IP suite of Protocols.

 
by Dinesh Thakur

VPN (Virtual Private Network) Definition: VPN meaning that it is a private point-to-point connection between two machines or networks over a shared or public network such as the internet. A Virtual Private Network is a combination of software and hardware. VPN (Virtual Private Network) technology, can be use in organization to extend its safe encrypted connection over less secure internet to connect remote users, branch offices, and partner private, internal network. VPN turn the Internet into a simulated private WAN.



 
by Dinesh Thakur

The INSERT statement is used to add new row to a table. To insert new row(s) into a table, the table must be in your own schema or you must have INSERT privilege on the table. Only one row is inserted at a time with this syntax. You can insert literal values (26.5, 'DINESH), expres­sions containing operators and functions, null values etc. only.

 
by Dinesh Thakur

There are times when you want to prevent inheritance. Perhaps there is no need the extensibility for various reasons. If you know this for sure, there are advantages to declaring the final keyword precisely that.

Java has a special keyword called final that can use for creating final methods, final classes, and final variables. The final modifier is void, which simply means that no value is returned.The final modifier indicates that the value of this member cannot change. We get a compile-time error if our program tries to change its contents. Each of these is explained in more detail next.

 
by Dinesh Thakur

Java is a robust, general-purpose, high-level programming language and a powerful software platform. It is also object-oriented, distributed, portable and multi-threaded. Java follows the 'Write - once - run - anywhere' approach. All Java programs must run on the Java platform that has two components, the Java Virtual Machine (JVM) and the Java Application Programming Interface (API).

 
by Dinesh Thakur

Keywords also are known as reserved words are the pre-defined identifiers reserved by Java for a specific purpose that inform the compiler about what the program should do. A Keyword is that which have a special meaning those already explained to the java language like int, float, class, public, etc. these are the reserved keywords. These special words cannot be used as class names, variables, or method names, because they have special meaning within the language.



 
by Dinesh Thakur

In computer science, “type casting” and “type conversion” refers when there is either implicitly or explicitly is a conversion from one data type to another. When both types of expression are compatible with each other, then Data type conversions from one type to another can be carried out Automatically by java compiler. However, there is a technical difference between type conversion and type casting, i.e. type conversion is carried out “automatically” by java compiler while the "type casting" (using a cast operator) is to be explicitly performed by the java programmer.It is usually classified into two categories



 
by Dinesh Thakur

Type Casting: The process of converting one data type to another is called casting. Casting is often necessary when a function returns a data of type in different form then we need to perform an operation. Under certain circumstances Type conversion can be carried out automatically, in other cases it must be "forced" manually (explicitly). For example, the read() member function of the standard input stream (System.in) returns an int. If we want to store data of type int returned by read() into a variable of char type, we need to cast it :



 
by Dinesh Thakur

Java Tokens:- A java Program is made up of Classes and Methods and in the Methods are the Container of the various Statements And a Statement is made up of Variables, Constants, operators etc . 



 
by Dinesh Thakur

Java Literals: A literal in java refers to a fixed value that appears directly in a program. Java define five primary types of literals. By literal we mean any number, text, or other information that represents a value. This means what you type is what you get. They are commonly known as constants. We will use literals in addition to variables in Java statement.



 
by Dinesh Thakur

Identifiers in Java. A Java identifier is the symbolic name that is used for identification purpose. In Java, an identifier can be a variable name, constant name, method name, class name, array name, packages name or an interface. Few authors term variables as an identifier. For example : int score = 100;

 
by Dinesh Thakur

Java is the object-oriented programming language, similar to C++ high-level programming language and architecture neutral developed by Sun Microsystems in 1995 and later acquired by Oracle Corporation. Java was originally called OAK. Java is a computing platform for application development. Object-Oriented meaning the capability to reuse code. Secondly, it is platform independent, i.e., we don't have to develop separate applications for different platforms. It is possible to develop a single application which can run on multiple platforms like Windows, UNIX, and Macintosh systems. Java designed for hand-held devices and set-top boxes.

 
by Dinesh Thakur

The objects in our programs exist only while the program is executing. When the program closed, these objects cease to exist. How can we save an object in our program and restore it when the program rerun? For example, suppose that we are playing a computer chess game. We close the game before it finished. When we restart the game, it should resume from where we had left it, instead of from the beginning. One way to accomplish this would be to save information about the game (such as the locations of various game pieces, scores, and so forth) to a file, and then read this information back from the file to restore the game to the state where we had left it when it runs next. This is the idea behind serialization. Serialization is saving an object's state as a binary stream (that is, as a sequence of bytes). When an object is serialized, it is said to be flattened or deflated. The reverse process of constructing an object from the binary data is known as deserialization. Thus, a deserialised (or inflated) object is one whose state has restored.



 
by Dinesh Thakur

When you create an object by instantiating a class, the object uses some memory. After an object in memory has been used and is no longer needed, it is sensible to free memory from that object. Unlike some object-oriented languages where you have to explicitly destroy the objects that are no more references to that object. References that held in a variable naturally dropped when the variable goes out of scope. Alternatively, we can explicitly drop an object reference by setting the variable to null. which is a tedious and error-prone task, Java follows a different approach.

 
by Dinesh Thakur

In Java 1.5, a new class known as Scanner class was introduced to simplify the task of getting input from the user. The Scanner class is in java.util package which allows the user to read the data dynamically from the keyboard. It can be used to read a File on the disk. The Java Scanner class extends Object class is present in java.lang package and implements Iterator and Closeable interfaces.



 
by Dinesh Thakur

The this keyword in Java is used when a method has to refer to an object that has invoked it. It can be used inside any method to refer to the current object. This means that this is always used as a reference to the object on which the method was invoked. We can use this anywhere as reference to an object of the current class type is permitted.

 
by Dinesh Thakur

Objects and classes are the essential concepts in OOP as they are what we use for writing our programs. Java objects may be both physical and logical entities, but classes are only logical entities.

In the real world, you'll often find many individual objects all of the same kind.All the objects that have similar properties and similar behavior are grouped together to form a class.

 
by Dinesh Thakur

The different languages reflect the different styles of programming. OOP or object-oriented programming is a style of programming with a firm basis in several concepts. Those concepts revolve around objects and classes and include Polymorphism, Encapsulation, Inheritance, Abstraction and more.  Java is one of the most popular of all the object-oriented programming languages, as well as one of the easiest to learn and use.   
Any application built on objects in Java is an object-oriented application and is based on the declaration of one or more classes, with an object created from those classes and the interaction between the objects.    

 
by Dinesh Thakur

Initializing a variable is considered very helpful while making programs. We can initialize variables of primitive types at the time of their declarations. For example:

int a =10;

In Object Oriented Programming language (OOPL) like Java, the need of initialization of fields of a new object is even more common. We have already done this using two approaches.

 
by Dinesh Thakur

Polymorphism is a very powerful concept that allows you to design amazingly flexible applications. The word 'Polymorphism: is derived form two Greek words 'poly' which means many and 'morphos' which means forms. So, polymorphism means the ability to take many forms.

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.