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How to Declare Classes with Members: JAVA

In order to bring a class into existence in Java program, it should be declared. A class is declared using keyword class. The generic syntax for class declaration in Java is:

Class   <class_name>
    Statements defining class come here

The angle-brackets < > mean these names are to be provided by the programmer and [ ] brackets mean, this part is optional. The class name must be provided while declaring a class. This is used to refer to the class whenever an instance (the object) of the class is created. The class name must be a legal identifier in Java. While naming classes, generally nouns are used and the first letter is given in uppercase e.g., City or Date etc. the curly brackets { } mark the beginning of a class and/or a method. The curly brackets are also used to specify block statements.

A class is a blueprint or prototype that you can use to create many objects. The implementation of a class is comprised of two components: the class declaration and the class body.

classDeclaration   {
    // classBody

When a class is declared, no memory space is allotted to it. This is because a class is simply a blueprint or logical placeholder containing objects and method. Memory space is allocated when objects of a class type are created.

The Class Declaration

The class declaration component declares the name of the class along with other attributes such as whether the class is public or not.

The Class Body

The class body follows the class declaration and is embedded with in curly braces ‘{‘ and ‘}’. The class body contains declaration for all instance variable and class variable (known collectively as member variable) for the class. In addition, the class body contains declarations and implementations for all instance methods and class methods (known collectively as methods) for the class. The following template shows the form of a class definition that is most commonly used; however, it is legal to intermix the method definitions and the instance variable declaration.
Public class class_Name    {
. . . . . .
     . . . . .


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Memory representation of Linked List

             In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.

               Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:

      Suppose next node is allocated at an address 506, so the list becomes,

  Suppose next node is allocated with an address with an address 10,s the list become,

The other way to represent the linked list is as shown below:

 In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of next node. The last node …