What is the Difference Between Interface and Public Interface? Unveiling the Mystery

The Basics of Interfaces in Programming

You know, when you’re diving into object-oriented programming (OOP), the terms “interface” and “public interface” come up a lot. But—wait, what’s the actual difference between the two? If you’re anything like me, you’ve probably stumbled across these terms, scratching your head and wondering, “Are they really that different?”

Let’s clear this up once and for all. First, let’s talk about the concept of an interface in general. An interface in programming, especially in languages like Java or C#, is like a contract. It defines a set of methods that a class must implement, but it doesn’t say how these methods should be implemented. Think of it like a list of expectations, without telling you the actual recipe. It ensures that a class adheres to a specific structure, while still allowing flexibility in the implementation.

Understanding Public Interface

What Does "Public" Mean in This Context?

Okay, now here's where it gets interesting. When we talk about a "public interface," we’re usually referring to the accessibility of that interface. “Public” means that the interface is accessible to any class in your program, regardless of where it’s located.

Let’s say you’re working in a big project with multiple packages. If an interface is marked as public, any class, no matter where it resides, can implement it. It’s like inviting anyone to your party—no closed doors.

In contrast, an interface without the public modifier is package-private in Java, meaning it’s only accessible within the same package. So, yeah, not everyone gets an invite. Now, if you're thinking, "But, does it really matter?" Well, trust me, it does, especially when working with large systems where modularity and access control are essential.

Why Public Interfaces Are Crucial

Public interfaces are key when you want to expose a set of functionalities for other parts of your application or even external applications to use. You might want other developers to implement certain behaviors but don’t want to give them the entire codebase. By using a public interface, you allow only the necessary methods to be accessible, while keeping the rest of the code hidden. Pretty neat, right?

Interface vs Public Interface: What's the Difference?

The Key Distinction

Here’s the thing: the core difference between an interface and a public interface boils down to visibility. Both define a contract for implementing classes, but the public interface is open for all to see and use. An interface, without the public modifier, may be restricted to only specific parts of your program.

I know, it sounds a little confusing at first, but I had the same question when I was learning this concept. In fact, just the other day, I was discussing this with a friend who’s a senior developer. He was working on a huge enterprise application, and we had a back-and-forth about which interfaces should be public and which should be private to avoid unnecessary exposure. He emphasized how important it is to limit access where possible—keeps things clean and secure.

Real-World Example: A Simple API

Let me throw in a quick example from one of my projects. I had to design a small API for a service where users could interact with data. I exposed a public interface, IUserService, which included methods like createUser() and getUser(). These were the only methods other classes needed to interact with. Behind the scenes, I had a more complex UserServiceImpl class that handled all the actual logic, but the other classes never interacted with it directly. They only saw the public interface.

So, if I hadn’t kept the interface public, or if I had left some methods package-private, the system wouldn’t have been as flexible. Other parts of the app wouldn’t have been able to use my user creation logic, which would’ve been a mess.

When Should You Use Public Interfaces?

The "When" and "Why" of Exposing Your Interfaces

It’s not always necessary to make an interface public. You don’t want to expose every detail of your system to the world. Consider the following:

1. Modularity: Public interfaces are great when you want to create modular systems where parts can be replaced or extended easily. For example, swapping out one service implementation for another should be a breeze if your interfaces are public.

2. Security: However, you don’t want to be too generous with your public interfaces. The more you expose, the greater the chance of a security risk. So think carefully—does it really need to be public?

I remember when I first started developing an API. I initially made almost everything public because, you know, I thought "the more, the better." Big mistake. As my project grew, I had to go back and rework the access levels, restricting visibility where it made sense.

Public Interfaces in Frameworks and Libraries

Public interfaces become essential when you’re building libraries or frameworks. Other developers need to interact with your code, but they shouldn’t have to know about every little detail. That’s where public interfaces shine. They provide a clean way to interact with your system without exposing all the internals.

Take Spring, for example. It defines public interfaces for almost everything. Want to work with data? There’s a public interface for that. Need to define a service layer? Yep, you’ll be using public interfaces. And that’s the beauty of it—it allows for flexibility while keeping things neat and secure.

Conclusion: Making the Right Choice

In the end, the decision between using a simple interface or a public interface boils down to the level of access you want to provide. A public interface opens up your methods to the world, while a regular interface can be more restricted, keeping certain parts of your code private and controlled.

My advice? Be thoughtful about when and where you expose your interfaces. Not everything needs to be public. Too much exposure can lead to chaos, especially in large systems where security and modularity are key. And don’t worry—if you make a mistake, you’ll learn from it (like I did). It’s all part of the process.

So, next time you’re designing your system, take a step back and think: Does this need to be public, or can it stay behind the curtains? Trust me, that simple decision will save you a lot of headaches down the road!

Is 165 cm normal for a 15 year old?

The predicted height for a female, based on your parents heights, is 155 to 165cm. Most 15 year old girls are nearly done growing. I was too. It's a very normal height for a girl.

Is 160 cm too tall for a 12 year old?

How Tall Should a 12 Year Old Be? We can only speak to national average heights here in North America, whereby, a 12 year old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12 year old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).

How tall is a average 15 year old?

Average Height to Weight for Teenage Boys - 13 to 20 Years

How to get taller at 18?

Staying physically active is even more essential from childhood to grow and improve overall health. But taking it up even in adulthood can help you add a few inches to your height. Strength-building exercises, yoga, jumping rope, and biking all can help to increase your flexibility and grow a few inches taller.

Is 5.7 a good height for a 15 year old boy?

Generally speaking, the average height for 15 year olds girls is 62.9 inches (or 159.7 cm). On the other hand, teen boys at the age of 15 have a much higher average height, which is 67.0 inches (or 170.1 cm).

Can you grow between 16 and 18?

Most girls stop growing taller by age 14 or 15. However, after their early teenage growth spurt, boys continue gaining height at a gradual pace until around 18. Note that some kids will stop growing earlier and others may keep growing a year or two more.

Can you grow 1 cm after 17?

Even with a healthy diet, most people's height won't increase after age 18 to 20. The graph below shows the rate of growth from birth to age 20. As you can see, the growth lines fall to zero between ages 18 and 20 ( 7 , 8 ). The reason why your height stops increasing is your bones, specifically your growth plates.