Data Types & Variables In Java

 In Java, data types represent the type of data that can be stored in a variable. Variables, on the other hand, are containers for storing data values. Here's an overview of data types and variables in Java:

Data Types:

1. Primitive Data Types:
   • Primitive data types are the most basic data types in Java.
   • They are predefined by the language and are not objects.
   • Java has eight primitive data types:
     • byte: 8-bit integer value.
     • short: 16-bit integer value.
     • int: 32-bit integer value.
     • long: 64-bit integer value.
     • float: 32-bit floating-point value.
     • double: 64-bit floating-point value.
     • char: 16-bit Unicode character.
     • boolean: Represents true or false.
2. Reference Data Types:
   • Reference data types are used to create objects and arrays.
   • They are references to objects in memory and do not hold the actual data.
   • Examples include classes, interfaces, arrays, and enums.

Variables:

1. Declaration:
   • Variables must be declared with a data type before they can be used.
   • Syntax: data_type variable_name;
2. Initialization:
   • Variables can be initialized with an initial value at the time of declaration.
   • Syntax: data_type variable_name = initial_value;
3. Naming Rules:
• Variable names must start with a letter, underscore (_), or dollar sign ($).
• They can contain letters, digits, underscores, and dollar signs.
• They are case-sensitive.
• They cannot be a reserved keyword.

• Examples:

// Primitive Data Types

byte byteVar = 127;

short shortVar = 32000;

int intVar = 1000000;

long longVar = 1000000000000L; // Note the 'L' suffix for long literals

float floatVar = 3.14f; // Note the 'f' suffix for float literals

double doubleVar = 3.14159;

char charVar = 'A';

boolean boolVar = true;

// Reference Data Types

String stringVar = "Hello, Java!";

Object objectVar = new Object();

int[] arrayVar = {1, 2, 3, 4, 5};