Variables in Java

Definition:

A variable is a named memory location used to store data. Its value can change during program execution.

Types of Variables in Java:

(1) Local Variables:-

Declared inside methods/blocks.
Must be initialized before use.

Syntax:

datatype variableName;

Example:











(2) Instance Variables:-
Declared inside a class but outside methods.
Each object has its own copy.
Syntax:
class ClassName {
    datatype variableName;
}
Example:

(3) Static Variables:-
Declared using static keyword.
Shared among all objects.
Syntax:

static datatype variableName;
Example:

























Identifiers in Java
Definition:
Identifiers are the names given to variables, methods, classes, and objects.
Rules for Identifiers:
Must begin with a letter, underscore (_), or dollar ($)
Cannot start with a digit
Cannot be a keyword (e.g., int, class)
Can contain letters, digits, _, $
Java is case-sensitive
Syntax:-
datatype identifierName;
Example:-