Errors and exceptions are inevitable in any software project, but how you handle them can make a big difference in the quality, reliability, and maintainability of your code. In this article, you will learn some best practices for dealing with errors and exceptions in your code, based on the principles of clean code and software engineering.
Errors and exceptions are events that occur when something goes wrong during the execution of your code. Errors are usually caused by external factors, such as network failures, file corruption, or insufficient resources. Exceptions are usually caused by internal factors, such as logical errors, invalid input, or unexpected conditions. Both errors and exceptions can disrupt the normal flow of your program and cause unwanted results or crashes.
Handling errors and exceptions is important for several reasons. First, it helps you prevent or mitigate the negative consequences of errors and exceptions, such as data loss, security breaches, or user dissatisfaction. Second, it helps you debug and fix the root causes of errors and exceptions, by providing useful information and feedback. Third, it helps you improve the readability and maintainability of your code, by separating the normal logic from the error handling logic.
Handling errors and exceptions in your code requires following some general guidelines. Try-catch-finally blocks can be used to catch and handle exceptions, with try blocks containing the code that may throw an exception, catch blocks containing the code that handles the exception, and finally blocks containing the code that always executes regardless of the exception. Additionally, specific exception types should be used to catch and handle different kinds of exceptions to avoid catching unintended exceptions. Descriptive and informative messages should be used to communicate the details of the exception to the user or developer. Logging and debugging tools should also be used to record and analyze the exceptions that occur in your code. Finally, best practices and design patterns should be employed to avoid or reduce errors and exceptions in your code, such as input validation, error handling libraries, defensive programming, etc.
Clean code is code that is easy to read, understand, and modify. To achieve clean code, you should handle errors and exceptions in the right way. For example, use exceptions rather than return codes or flags, as they are more expressive and consistent. Additionally, never ignore or swallow exceptions, and don't return or throw null pointer exceptions. Additionally, avoid using checked exceptions as they can violate the abstraction and cohesion of your code. Finally, don't use generic exceptions as they can mask the specific nature and cause of the exception. Instead, use specific or custom exceptions and name them according to their meaning and context.
While somewhat language dependent, I strongly disagree with the advice to favor exceptions over errors. Errors are usually *expected* problems at runtime while exceptions are generally *unexpected* problems on a code path. Generally, avoid using exceptions for flow control. In many languages, reporting errors is faster than raising and rescuing exceptions, so an expected error like "404 Not Found" when checking the validity of a URL might simply be reported as such before moving along to the next item in the list. However, an *unexpected* state such as "500 Internal Server Error" is more problematic, and likely justifies the overhead of creating exception objects and stack traces for analysis, debugging, and exception handling.
Testing your error and exception handling is essential to ensure that your code works as expected and handles all possible scenarios. To do this, you can use unit tests to verify the behavior of your code under normal and exceptional conditions. Test frameworks like JUnit or TestNG can be used to write and run these tests, while mock objects, stubs, or fakes can be used to simulate the dependencies and interactions of your code. Additionally, integration tests can be used to verify the behavior of your code when it interacts with other components or systems, with test frameworks such as Selenium or Cucumber. Fault injection techniques can also be used to introduce errors and exceptions into your code deliberately and observe how it reacts, using tools such as Chaos Monkey or Simian Army. This will help measure the impact on the performance, reliability, and resilience of your code.