Java Access Modifiers: public, private, protected, Controlling Visibility

Java access modifiers are used to control the visibility scope of class members, ensuring code security and maintainability. There are mainly four types: **public**: The most open; accessible directly by all classes (same package or different packages). **private**: The most restrictive; only accessible within the current class. Other classes (including those in the same package) cannot access it directly and must operate indirectly through the class's public methods. **protected**: Intermediate level; accessible directly by classes in the same package, and by subclasses of different packages (regardless of whether they are in the same package) through inheritance. **Default modifier** (no modifier): Accessible only by classes in the same package; invisible to classes in different packages. In actual development, member variables are recommended to use private, with access controlled via public methods. Class visibility is chosen as needed: default (same package) or public (cross-package). protected is used in scenarios requiring subclass inheritance access. Mastering modifiers enhances code security and clarity.