Java programmer expert
Java coding best practices
In today’s article we will focus on proven and useful tips and tricks for creating quality code, which we at msg life like to use and which will help you to improve the formatting, structure, readability and functionality of your Java code. Coding in Java becomes enjoyable when we no longer have to worry about how the code looks, but rather about what it does.
In the article you will learn:
Libraries
We use software libraries so that we don’t have to program everything manually.
- Use third-party libraries only if necessary. If they are not updated, they may be a source of future code vulnerabilities.
- Use one testing framework, not more. For example, JUnit or TestNG.
- We recommend using Mockito to simulate functionality in tests.
- Several libraries offer very similar methods, pick one library and use that one consistently.
Code formatting
Proper code formatting is very important because accurate and consistent indentation along with appropriate spacing can make reading and editing code much easier.
- Write a single space around the operators on the left and right.
- Do not use tabs for indentation; use spaces instead.
- Split long lines of code into multiple lines by starting the next line with an operator.
- Follow formatting rules consistently across all Java projects.
- Take advantage of the features of modern programming environments when formatting code (e.g. automatic formatting).
Packages
Packages are used to organize related and co-related code.
- Always use lower case in package names.
- The name of the package must indicate its purpose.
- Organize the packages logically into a hierarchical project structure.
Annotations
They provide additional information about the code in the form of metadata.
- Limit the use of annotations to make the code cleaner.
- When using the @Deprecated annotation, provide both the reason and an alternative in the javadoc comment.
- Annotations like @Nonnull and @Nullable should be used sparingly and judiciously.
- Use the @VisibleForTesting annotation only temporarily in tests when you need to extend access rights from private to package private.
Comments
They are intended to help clarify the code, therefore:
- If the code is written in a simple and understandable style, no comments are necessary.
- Don’t write (or generate) any javadoc for getters and setters.
- For (package) private methods, prefer an implementation note and avoid writing javadoc.
Exceptions
We use them for unexpected situations in code.
- Use unchecked exceptions to make the code more flexible.
- Use the predefined JDK exception types and avoid creating your own.
Naming
We try to choose appropriate titles that reflect the purpose and importance of the individual parts of the program.
- Avoid abbreviations and choose meaningful names.
- Use adverbs for boolean variables (e.g. disabled)
- For other types and variables, use nouns (e.g. ArrayList (class), element (variable)).
- For methods, use verbs (e.g. add, remove).
- In the method name, indicate the intention of the method (e.g. calculateSpeed).
- Be precise, e.g. instead of the general variable time for storing time in hours, it is better to use timeInHours).
- Avoid duplication (e.g. instead of addElement(element), use add(element)).
Methods
Methods form the basic unit of code in Java, so it is important to follow best practices when writing them.
- A method should solve only one problem (follow the Single Responsibility Principle).
- Each method should have a clear single purpose.
- Well-structured code contains short methods (ideally fewer than 15 lines). If a method is longer, there should be a good reason.
- Avoid repetition.
- Avoid changing the input to the method; instead, calculate the output.
- If you need to modify the input parameter, indicate this in the method name (e.g., prefix with update.
- Use functional programming and modern APIs.
Interfaces
Interfaces define rules that need to be implemented by classes.
- Don’t use interfaces if they aren’t needed.
- If only one class will use the interface, its use becomes meaningless.
- Apply the Interface Segregation Principle.
- Design interfaces for specific purposes, avoiding generic interfaces.
Classes
Classes are the basic building blocks of any Java application.
- Each class should handle only one specific concept or functionality.
- Avoid creating multi-functional classes that do everything.
- Decide whether your class will focus on data or data manipulation. For example, a data class maintains state (e.g., Matrix). A class focused on working with data defines behaviour (e.g., MultiplicationService).
- Prefer private methods. Use public methods only when necessary for interaction with the outside world.
- Avoid the protected modifier in tests, use package-private instead.
We hope these tips and tricks will help you write cleaner, clearer, and more efficient Java code. If you’re a Java developer looking for work, check out our employee benefits and respond to our job offers!
