class
Declares a class — a description of objects: their fields and methods.
Available since: Java 1.0
Syntax
class Name { fields; constructors; methods }Examples
A class with fields, a constructor and a method:
class BankAccount {
private final String owner;
private double balance;
BankAccount(String owner) {
this.owner = owner;
}
void deposit(double amount) {
balance += amount;
}
String info() {
return owner + ": " + balance;
}
}
void main() {
var account = new BankAccount("Anna");
account.deposit(50);
account.deposit(25.5);
IO.println(account.info());
}Output:
Anna: 75.5Notes
In a regular project each public class lives in its own file with the same name: BankAccount.java. In a compact source file with void main() (Java 25) classes can be declared next to main.
If a class only holds data, a record is shorter.
See also
- new — Creates a new object or array and calls the constructor.
- this — A reference to the current object — the one whose method or constructor is running.
- record — Declares a record — an immutable data class with ready-made equals(), hashCode() and toString().
- extends — Declares inheritance: the class gets the parent's fields and methods.
In the tutorial
- Classes and objects — What classes and objects are in Java: fields, methods, the new operator, default values and object references.