25 Essential Tips Every Junior Backend Engineer Should Follow

1. Write Good Comments

Many developers avoid writing comments due to time pressure or the belief that code should be self‑explanatory. However, without comments, future maintenance becomes difficult, especially for complex logic. Write concise comments for key methods, steps, and algorithms to aid future understanding.

2. Write More Unit Tests

Writing unit tests for new utility classes helps ensure correctness during refactoring. Even if time is tight, add tests later to reduce future debugging effort and improve code quality.

3. Refactor Your Own Messy Code

Continuously refactor old code to improve readability, extract common methods, rename unclear identifiers, and apply design patterns where appropriate. This practice drives personal skill growth.

4. Code Review Is Important

Code reviews help discover bugs, bad practices, and personal coding habits, accelerating improvement. If a formal review process is unavailable, review your own code before merging.

5. Use EXPLAIN to Check Execution Plans

After writing SQL queries, use the EXPLAIN keyword to verify whether indexes are used. Proper indexing can reduce execution time by orders of magnitude.

6. Prepare a Release Checklist

Before deployment, create a checklist covering dependency order, data initialization scripts, scheduled tasks, configuration updates, permission assignments, and other release steps to avoid missing critical actions.

7. Write Good API Documentation

Clear API docs reduce communication overhead and prevent misunderstandings about endpoints, parameters, and response fields.

8. Estimate Request Volume Early

Assess expected QPS with product owners. Perform load testing and implement rate limiting to protect services from overload.

9. Ensure API Idempotency

Design APIs to be idempotent, using unique constraints or explicit checks, to prevent duplicate data from rapid repeated calls or automatic retries.

10. Be Cautious When Changing API Parameters

When modifying parameters, evaluate impact on callers, maintain backward compatibility, and avoid deleting or renaming fields without a migration strategy.

11. Add Retry Logic for Third‑Party Calls

Wrap remote calls with retry mechanisms to handle connection timeouts and improve reliability.

12. Backup Data Before Online Operations

Always back up tables before performing data fixes. Example backup script:

create table order_2022121819 like `order`;
insert into order_2022121819 select * from `order`;

13. Avoid Deleting Online Fields Lightly

Deleting a column without updating all related code can cause runtime exceptions. Coordinate schema changes with deployments.

14. Choose Appropriate Field Types and Lengths

Use the smallest suitable data type, prefer char for fixed‑length strings, varchar for variable lengths, bit for booleans, tinyint for enums, bigint for primary keys, decimal for monetary values, and timestamp / datetime for dates.

15. Avoid Querying Too Much Data at Once

Large result sets can cause OOM errors. Implement pagination or batch fetching, especially when exporting data.

16. Multithreading Is Not Always Faster

Multithreading helps for I/O‑bound or remote‑call workloads, but for simple CPU‑bound loops it may add overhead. Choose the appropriate model based on the task.

17. Pay Attention to Transaction Management

Use declarative @Transactional or programmatic TransactionTemplate to ensure atomicity across multiple tables, and avoid large transactions that can cause timeouts or deadlocks.

18. Prevent Decimal Precision Loss

Floating‑point types like float and double can lose precision. Prefer BigDecimal created via BigDecimal.valueOf() to maintain exact values.

19. Prefer Batch Operations

Replace per‑record loops with batch updates to improve performance, e.g., userMapper.updateForBatch(userList).

20. Use Distributed Locks Sparingly

In distributed environments, rely on database pessimistic/optimistic locks or Redis/ZooKeeper distributed locks instead of synchronized, which only works on a single JVM.

21. Apply Asynchronous Processing When Appropriate

Offload non‑critical work to jobs or message queues, while keeping latency‑sensitive logic synchronous.

22. Adopt Good Git Commit Practices

Commit frequently with clear messages, include task IDs when possible, and pull before pushing to reduce conflicts.

23. Leverage Open‑Source Utility Libraries

Use libraries like Apache Commons, Google Guava, or Hutool to avoid reinventing common functionality (e.g., Lists.partition() for list splitting).

24. Cultivate a Habit of Writing Technical Blogs

Documenting what you learn reinforces knowledge, improves communication skills, and showcases expertise to recruiters.

25. Read High‑Quality Source Code

Study the source of frameworks such as JDK, Spring, and MyBatis to understand underlying principles, design patterns, and potential pitfalls.