Class in Java::

Source: Dev.to

Class

Definition

A class is a blueprint or template used to create objects. It defines the properties (variables) and behaviors (methods) that the objects created from it will have.

Declaration

A class must be declared using the class keyword.

class MyClass {
}

Naming Rules

• The class name must start with a letter (A–Z or a–z).
• It cannot start with a digit.
• It must not contain spaces.
• Only the characters _ and $ are allowed as special characters.
• Java reserved keywords cannot be used as class names.
• By convention, the class name should start with a capital letter, and if it contains multiple words, each word should start with a capital letter.

class StudentDetails

Body and Structure

The body of a class must be enclosed within curly braces {}.

class Car {
    // fields and methods
}

File Naming

• A .java file can contain only one public class.
• If a class is declared as public, the file name must match the public class name.

public class Student {
}

Access Modifiers

• A class can have an access modifier such as public, or no modifier (default package‑private).
• Top‑level classes cannot be private or protected.

Main Method

To execute a Java program, the class must contain the main() method.

public static void main(String[] args) {
    // program entry point
}

Multiple Classes in One File

Multiple classes can be defined in a single file, but only one of them may be declared public.