Best Practices for Organizing Java Classes: A Guide to Enhancing Readability and Collaboration in Codebases

Today i was creating multiple classes in a single file and found out some difficulties associated with it and thought to share this valuable info. Keep Learning!!!

Each file in java can contain at most one public class. The name of the file must match the name of this public class. So, if you have a public class named LinkedQueue, the file must be named LinkedQueue.java. All other classes in the file must not be declared as public. They will have package-private visibility, meaning they can be accessed from other classes in the same package. The non-public classes can be used by any other classes in the same package, but they are not visible to classes in other packages.

public class LinkedQueue {
    // Your code here
}

class Queue {
    // Your code here
}

In this code, LinkedQueue is a public class and Queue is a package-private class. Both classes can be used within the same package, but only LinkedQueue can be accessed from other packages. Remember to save this file as LinkedQueue.java.

If you are working on a small project by yourself, having multiple classes in a single file may not seem like a big deal. But things can get complicated quickly as the project grows, or when you start working with a team. Here’s why:

1. Organization: Having each class in its own file makes it much easier to manage your codebase. For example, if one needs to find a Queue class, one can simply find the Queue.java file. This is faster and easier than checking for unlinked classes in the LinkedQueue.java file.
   Readability: Much easier to understand a file with a single class. The purpose and actions of a class are more obvious when they are not mixed with unrelated rules.
2. Integration conflicts: When multiple people work on the same codebase, they often have to make changes to the same file. If two people make different changes to the same file, you will get merge conflicts, which can be difficult to resolve. By having each class on its own file, you reduce the chance of two people exchanging the same file, thus reducing the chance of joint conflicts
3. Version control: When that class is in its own file, it’s easy to track changes to the class over time. If a category is in a file with multiple other categories, changes made to all other categories in that file’s change log will also be included, making it difficult to see the history of the category of interest
4. Testing and debugging: With each class in its own file, you can easily test that class in isolation. You can also have a clear stack trace when debugging, because class names in the stack trace map directly to file names in your codebase.

In conclusion, although Java allows you to load multiple classes in a single file, it is generally best practice to have each top-level class in its own file. This makes your code easier to read, understand, and maintain, both for you and for anyone else who might work on your code in the future.