Access modifiers (public, protected, default, private)

Access modifiers control the visibility of classes, fields, methods, and constructors.

Modifier	Class	Package	Subclass	World
private	✅	❌	❌	❌
default (no modifier)	✅	✅	❌	❌
protected	✅	✅	✅	❌
public	✅	✅	✅	✅

Examples:

public class BankAccount {           // accessible everywhere
    private double balance;          // only within this class
    String accountNumber;            // default: accessible within package
    protected double interestRate;   // accessible in subclasses and package
    public String owner;             // accessible everywhere
}

Class‑level modifiers: A top‑level class can be public or default (package‑private). It cannot be private or protected.

Best practices:

• Keep fields private and provide public getters/setters if needed (encapsulation).
• Use default for package‑internal implementation details.
• Use protected for members intended to be inherited.
• Use public only for the API that external code should use.