In Java, a data type is a classification that specifies which type of value a variable can hold. Java is a statically typed language, meaning that variables must be declared with a specific data type before they can be used. This helps in identifying the type of data that is being stored and the operations that can be performed on that data.
Java data types are divided into two categories:
1. Primitive Data Types
Primitive data types are the most basic data types available in Java. They are predefined by the language and named by a reserved keyword. Java has 8 primitive data types:
byte: 8-bit signed integer. Range: -128 to 127.
short: 16-bit signed integer. Range: -32,768 to 32,767.
int: 32-bit signed integer. Range: -2^31 to 2^31-1.
long: 64-bit signed integer. Range: -2^63 to 2^63-1.
float: Single-precision 32-bit IEEE 754 floating point.
double: Double-precision 64-bit IEEE 754 floating point.
boolean: Represents one bit of information with two possible values: true or false.
char: Single 16-bit Unicode character. Range: '\u0000' (or 0) to '\uffff' (or 65,535).
2. Reference Data Types
Reference data types are more complex types and they refer to objects. They are created using defined constructors of the classes. They include:
Classes: A class is a blueprint for creating objects (a particular data structure), providing initial values for state (member variables or fields), and implementations of behavior (member functions or methods). For example: String, Scanner, etc.
Interfaces: An interface is a reference type, similar to a class, that can contain only constants, method signatures, default methods, static methods, and nested types.
Arrays: An array is a container object that holds a fixed number of values of a single type. The length of an array is established when the array is created. After creation, its length is fixed.
Summary
Primitive Data Types: byte, short, int, long, float, double, boolean, char
Reference Data Types: Classes, Interfaces, Arrays
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