Access Modifiers in Java

Access modifiers control where a class, field, or method can be accessed.

1. Access Levels

Modifier	Same Class	Same Package	Subclass in Other Package	Everywhere
`private`	Yes	No	No	No
`no modifier`	Yes	Yes	No	No
`protected`	Yes	Yes	Yes	No
`public`	Yes	Yes	Yes	Yes

private
   ↓
same class only

default
   ↓
same package

protected
   ↓
same package + subclasses

public
   ↓
everywhere

Accessible from anywhere.

public class Dog {

    public void bark() {
        System.out.println("Woof!");
    }
}

A public top-level class can be used by classes in other packages.

When no access modifier is specified, the member is package-private.

class Dog {

    void bark() {
        System.out.println("Woof!");
    }
}

Accessible only within the same package.

default is commonly called package-private. It is not written as default.

Accessible only inside its own class.

class Dog {

    private String name;

    private void bark() {
        System.out.println("Woof!");
    }
}

Other classes cannot directly access name or bark().

Accessible:

class Animal {

    protected void eat() {
        System.out.println("Eating...");
    }
}

A subclass can access it:

class Dog extends Animal {

    void test() {
        eat();
    }
}

Use the most restrictive access level that makes sense.

Usually:

private → preferred
protected/default → when needed
public → only when necessary

Prefer:

class Person {
    private String name;
}

instead of:

class Person {
    public String name;
}

private fields give you better encapsulation and allow you to change the internal implementation later without affecting other classes.

Use private by default unless you have a good reason to expose something.

Public fields are generally avoided, except for things such as constants.