Data Types in Java

In Java, data types are used to define the type of data that a variable can hold. There are two types of data types in Java: primitive and non-primitive.

1. Primitive Data Types:

Java has eight primitive data types, which are:

• byte: 8-bit signed integer. Example: byte age = 20;
• short: 16-bit signed integer. Example: short temperature = -10;
• int: 32-bit signed integer. Example: int salary = 50000;
• long: 64-bit signed integer. Example: long distance = 1000000L;
• float: 32-bit floating-point number. Example: float pi = 3.14f;
• double: 64-bit floating-point number. Example: double weight = 70.5;
• boolean: true/false value. Example: boolean isStudent = true;
• char: 16-bit Unicode character. Example: char grade = 'A';

Rules for using primitive data types:

• You must declare the data type of a variable before using it.
• You must assign a value of the same data type to the variable.
• Numeric values can be expressed using literals (e.g. 10, 20.5, etc.).
• You can perform arithmetic operations on numeric values.
• Booleans are used in conditional statements, loops, and other control structures.

2. Non-primitive Data Types:

Non-primitive data types are also known as reference types. These data types are created using class definitions or interfaces. Some examples of non-primitive data types are:

• String: a sequence of characters. Example: String name = "John";
• Array: a collection of values of the same type. Example: int[] numbers = {1, 2, 3, 4, 5};
• Class: a blueprint for creating objects. Example: Scanner scanner = new Scanner(System.in);

Rules for using non-primitive data types:

• Non-primitive data types must be instantiated using the new keyword.
• You must declare a variable with the class or interface type.
• You can call methods on non-primitive data types.

In summary, in Java, data types are used to define the type of data that a variable can hold. There are primitive and non-primitive data types, each with its own rules for usage.