Learn how public, private, protected, and default access modifiers shape your code.

Access modifiers are the gatekeepers of your code. They decide who can see what, and that tiny decision can ripple through a whole project. For anyone building apps, games, or services—especially folks chasing a career path through Revature’s programs—grasping these modifiers is a real confidence boost. Think of them as the knobs you tune to get clean, maintainable, and secure code.

Let’s break down the four kinds you’ll most often encounter: Public, Private, Protected, and Default. Yes, it’s a quick line-up, but it’s the kind of thing you’ll want to have stamped in your memory because you’ll see these terms again and again in interviews, code reviews, and real-world projects.

What are these modifiers, and why should you care?

• Public: The open door

• Private: The fortress

• Protected: The family access

• Default: The package-private setup

Public: an open door to the world

Public means anyone can reach the member—method or variable—no matter where they’re coming from. It’s the “everybody can see this” setting. When you design a class that’s meant to be used widely, public members are your go-to. They’re the surface you present to the rest of your codebase (and, let's be honest, to other developers who might reuse your class).

Example on the street: imagine a Calculator class with a public add(int a, int b) method. You write that method to be straightforward and reliable, so any other part of your program can call calc.add(3, 5) without needing special permissions. Public is the friendly face of your code.

But a word of caution: exposing too much can invite trouble. If you make everything public, you lose control over how it’s used, and you open the door to bugs caused by unexpected inputs. Public is powerful, but with great power comes great responsibility.

Private: the fortress

Private is all about limits. Private members are tucked away inside the class; no other class, not even subclasses, can reach them directly. This is the heart of encapsulation: hide the internal state and expose only what’s necessary through controlled interfaces (usually public or protected methods).

Think of a private field like a password or a secret recipe. You don’t want random parts of your program poking at it directly. Instead, you provide a public getter or setter—or better yet, a method that does the job without revealing the guts.

For example, in a User class you might store a password as private String passwordHash. External code shouldn’t read or tamper with that directly; you’d provide a method like boolean verifyPassword(String input) or a safe setter that applies validation before updating the value. Private keeps your class’s innards honest and stable.

Protected: family access with inheritance

Protected sits between public and private. It allows access within the same package (in languages like Java) and, crucially, in subclasses, even if those subclasses live in different packages. This makes protected a friend to inheritance: you can extend a class and still rely on certain helpers or state that aren’t meant for the whole world to touch.

Picture a base class called Vehicle with a protected int speed. Subclasses such as Car or Truck can tweak speed or use that speed value as part of their behavior, but outside code that doesn’t extend Vehicle shouldn’t reach in and fiddle with speed directly. Protected keeps the door slightly ajar for your class family while keeping the outside world at bay.

Default: the package-private lane

Default isn’t a word you shout loudly; it’s the quiet, default state nobody explicitly writes down. In languages like Java, if you omit an access modifier, the member becomes default (package-private). That means it’s visible to all classes in the same package but not to classes in other packages.

Default is handy when you’re organizing related classes into a tidy module, and you want them to interact freely behind the scenes without exposing those interactions to the wider application. It’s the “we’re in this neighborhood together” setting.

How these fit into real-world design

Encapsulation isn’t just a buzzword. It’s a practical choice that helps you manage the complexity of codebases as they grow. When you group related classes into packages or modules, default access can keep inter-thread communication efficient while still preventing external misuse. If you’re building a library or a framework, public surface methods define your API; private and protected members shield your internal behavior; default offers a lean middle ground for internal collaboration.

A quick mental model you can carry around

• Public = front door for everyone.

• Private = private rooms for sensitive stuff.

• Protected = shared spaces with family and trusted friends (aka subclasses).

• Default = friendly neighbors within the same module; not a global invitation.

Common misconceptions to watch out for

• Public isn’t always better. It’s tempting to make everything public to “avoid friction,” but that invites unintended usage and brittle code.

• Private isn’t “against sharing.” It’s a safeguard that forces clean interfaces and makes your class easier to reason about.

• Protected isn’t unconditional access for everyone who inherits. It’s a deliberate choice that preserves inheritance benefits while guarding core state.

• Default isn’t a mystery; it’s simply the package scope. If you’re designing a multi-module system, you may prefer explicit public/protected/private to avoid accidental leakage.

Memorable analogies that click

• Public is the town square; private is the locked diary; protected is the family wing of a house; default is the apartment block where neighbors in the same building can chat but strangers can’t wander in.

• Another angle: think of a software kit. The public API is the manual you hand to users; private parts are the gears hidden inside; protected tools are the spare bits your team members can adapt; default means “use within this kit only, unless you’re in the same workshop.”

Putting it into practice in your code

Let’s sketch a simple mental example you can picture when you’re coding. Suppose you’re crafting a small class that models a BankAccount.

• The balance field should be private. You don’t want anyone to nudge it directly; you want to guard against bad values and inconsistent states.

• A public getBalance() method can read the balance, but you might also offer a public deposit(amount) method that checks for positive amounts and updates the balance through a controlled path.

• If you have derived classes like SavingsAccount that need to know something about the balance, you might expose a protected method like applyInterest(double rate) so the subclass can use it without exposing how the balance is stored.

• If there’s a helper method used by several classes in the same package, you might keep that as default (package-private) to keep the surface clean but still handy within the module.

In a Revature-style project, you’ll encounter this kind of pattern a lot. You’ll be asked to design class hierarchies with careful boundaries between what’s public, what’s private, and what’s accessible to a subclass. The goal isn’t showy access control; it’s predictability. When other developers reuse your code, they’ll thank you for the well-placed guards that prevent subtle bugs.

Tips to sharpen your intuition

• Start with the minimum necessary visibility. If a member doesn’t need to be public, don’t declare it that way.

• Prefer getters and setters for private fields to preserve invariants and validation. This gives you a single point to enforce rules.

• Use protected sparingly. It’s a useful bridge, but it can leak implementation details if you’re not careful about how you design your class hierarchy.

• Document the intended use of public members. A short note helps teammates understand why something is exposed and how it should be used.

A practical, human-centered take

Code is a conversation. The way you expose or hide pieces of a class shapes that conversation. When a user of your code reads a public method named computeScore(), they should feel confident about what it does and what it requires. When they don’t, it’s usually a hint that the internal state is too exposed or the interface isn’t as clear as it could be. The four access modifiers are not just syntax—they’re a language’s way of helping you tell that story with fewer surprises.

For students and aspiring developers exploring Revature’s ecosystem, these concepts are stepping stones to more advanced topics like object-oriented design, design patterns, and clean architecture. They’re the building blocks that show up again and again, whether you’re tutoring peers, pairing with teammates, or preparing for code reviews. Getting comfortable with these basics now saves you headaches later.

Two quick memory tricks you can use

• The door test: If you were to name a method public, could it be called from anywhere? If yes, that’s a public door. If not, rethink the access.

• The family test: If a method or field is meant for subclasses or same-package siblings to use, think protected or default. If not, keep it private.

Wrapping it up

Access modifiers—Public, Private, Protected, and Default—frame how your code interacts with the rest of the system. They’re not about making life harder; they’re about making it smoother, safer, and more maintainable. When you design thoughtfully with these in mind, you’ll notice you’re building things that are easier to understand, easier to adapt, and easier to evolve over time.

If you’re exploring the kinds of problems you’ll see in modern software environments, you’ll find these concepts cropping up in everything from small utility libraries to large-scale services. They’re the quiet workhorses behind clean interfaces, reliable behavior, and teams that know how to move quickly without tripping over their own complexity.

And if you ever want to talk through a specific class you’re designing—how to choose between public, private, protected, and default in a given scenario—reach out. I’m happy to walk through examples, explain the tradeoffs, and help you map those decisions to real-world code.

In short: know the doors, understand the rooms, and you’ll navigate object-oriented design with a steadier hand. That clarity pays off, bite by bite, line by line.