How do you use the try-catch-finally blocks in OOP?

Exceptions are common in programming and must be handled gracefully. For example if a service sends 404, it's a good idea to show a fancy page not found error or HTML page, rather than displaying stack traces. That is one example to explain why you should be doing exception handling.

"Exceptions" is a reporting mechanism implemented across many programming languages many of which support OOP. "Checked exceptions" is a mistake made in the design of Java's implementation of this mechanism and not, so far as I am aware, repeated in any other language. (C++ made a related but different mistake with "exception specifications", but has since deprecated that syntax.)

An exception is fundamentally different from an error. An error is a mistake in syntax. Most statically compiled languages have tools built into the build process, or even better, the IDE what expose these errors. An exception occurs in syntactically correct code, but indicate your program has entered, or attempted to enter an invalid state. The main job of a software engineer is to make sure your program never enters an invalid state. Obvious examples might include a stack overflow exception where your program runs out of memory. A more nuanced example might be comprised of a custom exception class, which inherits from the language's base exception class and raises a custom exception in response to a problem with business logic.

Exceptions are great ways to catch errors and avoid throwing big error messages to user interface rather always use something good so users don’t get confused if something doesn’t work you could just add a message like this ‘ contact support with this error: etc..’ that would be great I think.

use exceptions instead of conditions, depending on the language it can be faster, but that's not the point. obviously if you use base Exception you are in the wrong job, but that's generally not your fault but those who pays you. try: assert .... except AssetionError: ..... instead of typing your favourite 5+ and or maybe not, who knows...human narrative. finally: whatever

To follow up on Yi?it's response, you could also make your own Exceptions, with their own subclass-Exceptions. Then, instead of something like: try { // some code that might throw an Exception } catch (ExceptionType1 ex1 | ExceptionType2 ex2) { this->message('How cool is that?'); } You could do... try { // some code that might throw an Exception } catch (SuperClassExceptionType ex) { this->message('How cool is that?'); } Here, SuperClassExceptionType would be the superclass of ExceptionType1 and ExceptionType2, and it may be better to have the message be hardcoded in that Exception (if it would always be a user-friendly message being outputted). Keep in mind, this doesn't mean you always use want to use a generic Exception..

Additionally; if two or more catch blocks contain exactly the same codes, this indicates that it can be shortened using 'catching multiple exceptions' technique. try { // some code that might throw an exception } catch (ExceptionType1 e1) { this->message('How cool is that?'); } catch (ExceptionType2 e2) { this->message('How cool is that?'); } As you can see, it doesn't matter if we catch ExceptionType1 or ExceptionType2, we always call the message function with the same message. Therefore we can reduce redundancy in this piece of code by utilizing 'catching multiple exceptions'. try { // some code that might throw an exception } catch (ExceptionType1 | ExceptionType1 ex) { this->message('How cool is that?'); }

Within a try block, you place code that might throw an exception. If an exception occurs, the flow of execution is transferred to the catch block where the exception is caught and handled. Multiple catch blocks can follow a single try block to handle different types of exceptions specifically. This structure allows your program to continue running smoothly after dealing with the error, rather than crashing. To effectively use try-catch blocks, wrap only the code that might throw exceptions in the try block and use specific exception types in catch blocks for precise handling. This approach ensures that your application remains robust and user-friendly, even when unexpected errors occur.

Try catch blocks allow you to detect obvious possibilities for exceptions and account for them at run-time. Imagine writing a program that processes insurance claims in batches. Your program would use an OCR module to scan written forms. If a form lacks a proper signature, you need to throw an exception and the type of exception allows the calling application to perhaps route that form to customer service. If this class lacked exception handling, the batch run would simply crash and all the forms in the batch following the exception would not be processed. Good catch blocks try to account for every possible exception and offer a way to recover.

Because exceptions are not supposed to be used for control flow, my usage is pretty simple: write code without exception catching blocks, then run it, find all the main exceptions, write code to address them if possible and only then add a try catch if any remains that can be thrown. This cannot be easily done in Java because an option exists to oblige you to declare and try-catch every single exception that can be thrown. That option is terrible and should not be used in my opinion unless you're trying to ship (because then you absolutely want to make sure that all exceptions are considered!).

Utilizing the try-with-resources statement if you're working with resources that implement the AutoCloseable interface. It automatically ensures that the resources are closed, regardless of whether an exception occurs.

Finally blocks are used to clean up after an exception. Say you have a database application and your try-catch block catches an exception on a transaction. A transaction is a series of database operations that must complete as a unit. When you pay for something online, a debit comes from your account and gets posted as a credit to the seller. If either part of the transaction fails, you need to roll back the whole thing. A well coded catch will handle the rollback, but a finally block is executed regardless of whether the transaction was successful. In this example, it is an excellent place to close out your database connection and return that connection to a pool so other transactions can re-use that pooled connection.

It’s worthwhile to note that even though it is customary to see try-catch-finally blocks being used in tandem, a try-finally block can be used without a catch block, as shown in the example below: Lock lock = new ReentrantLock(); public void testMethod() { lock.lock(); try { // critical section } finally { lock.unlock(); } } This code demonstrates the usage of a try-finally block without a catch block. It ensures that before the JVM executes any code inside the try block, it has acquired a lock. The purpose of the finally block is to ensure that all locks are released before control is returned to the method caller, regardless of whether an exception is thrown, thereby preventing potential deadlocks.

It contains code that is guaranteed to execute regardless of whether an exception is thrown or caught within the preceding try-catch blocks. This makes it ideal for cleanup activities, such as releasing resources, closing files, or resetting states, which need to occur even if an error interrupts the program flow. To use a finally block effectively, place it after the last catch block of your try-catch structure. Ensure that the code within finally does not throw an exception, to avoid masking exceptions thrown from the try or catch blocks. This approach helps maintain clean resource management and ensures your program executes crucial post-operation tasks, maintaining stability and reliability.

Use the finally block to release any unmanaged resources you may be using like database connections, file pointers or printers etc. So even if your code is failing, the finally block will release the resources.

Properly handling exception is more than just error management. It's a reflection of code quality and adherence to best practices. First, Well-defined exceptions make code more readable and maintainable. e.g., use "good" and "explicit" names for exceptions like `FileNotFoundException` or `DatabaseConnectionFailedException` or `TransactionTimeOut` etc.. Second, leverage the power of inheritance for exceptions. Create a hierarchy of exceptions, which allows for catching errors at different levels of specificity, For instance, which `DataAccessException` might be a generic error, is children, `ReadFailedException` or `WriteFailedException` are more specific. Last, avoid catching all exceptions. Handle only meaningful ones.

You should make your own exception types which extend from the base exception object in your OOP language. You can use the types to effectively manage your error handling code. Make sure you provide a good explanation of what happened. If your exception handling is end-user facing, include an error message that assures the user the exception is not their fault (even if it is), and provide them with instructions on how they can rectify the problem if possible. Never expose a stack trace, or cryptic error message to the end-user. Put that stuff in the logs. Use online services like sentry.io to capture as much information as possible within your programs because you can't count on users to provide good information on what went wrong.

Best practices such as encapsulation, judicious use of inheritance, leveraging polymorphism, and following the SOLID principles, is crucial for creating clean, maintainable, and scalable software. These practices encourage code reuse, enhance modularity, and facilitate flexible system design. Additionally, employing design patterns provides standardized solutions to common problems, while effective exception handling ensures robust error management. Regular code refactoring and programming to interfaces rather than implementations further contribute to code quality. Moreover, adopting Test-Driven Development (TDD) and maintaining thorough documentation are essential for ensuring reliability and understandability of the code.

Avoid catching RuntimeExceptions- RuntimeExceptions usually indicate programming errors, and it's generally not recommended to catch them explicitly. It's better to fix the underlying issue causing the RuntimeException rather than catching and handling it.

1.Do not use empty catch blocks. 2.Try to catch specific exceptions than general exception class. For example 'FileNotFound' exception. This will give you more detailed information on what went wrong. 3.Take opportunity when you catch the exception to log it in file/database so that you can work on it and fi it. 4. Do not show the technical exception message directly to user as he/she may not understand it. Cast a user friendly message on what went wrong along with any action item to fix that exception, if any.

While this might not be the norm especially in OOPs and I do not recommend this type of approach there were a few cases where I was working for a banking program where the try catch block was essentially used instead of if else clause mind you this was primarily because we were calling multiple methods and sub programs and we had to make sure that the data had to validated as some of these calls returned the data in different types of objects but this helped us reduce the CPU consumption and handle any expectations we got and make modifications faster albeit this was the design of the module and interesting program where I worked on.

Try to think of corner cases. Once I created a puzzle for a multimedia training program that required users to match answers to question by dragging and dropping pieces on the screen. I invited an executive to do hallway testing. The first thing he did was drag all my pieces off the screen and drop them where you couldn't get to them anymore. The program wouldn't continue until the matching sequence was complete. I had considered every bad combination of answers. It never occurred to me that a user would do something that obviously ridiculous. The program was to ship to a corporate user base of around 10,000. If one out of a hundred dropped even one piece out of bounds, the call volume at the help desk would rise. Not what you want!

Custom Exception Hierarchy: Create a hierarchy of custom exceptions to handle different levels of error specificity. Logging: Use logging frameworks to log exceptions for later analysis without exposing technical details to end-users. Error Handling Strategies: Define clear strategies for handling different types of exceptions (e.g., retrying operations, notifying users, failing gracefully). Documentation: Document the exceptions that methods can throw and how they should be handled. Consistent Error Handling: Establish a consistent approach to error handling across the codebase to improve maintainability and readability.

In addition to technical aspects, fostering a culture of proactive error handling and continuous improvement within development teams is crucial. Encouraging knowledge sharing on effective exception management practices and leveraging tools for comprehensive error monitoring and reporting enhances application robustness. Regular reviews and updates to exception handling strategies based on evolving business requirements and user feedback are essential for optimizing application reliability and user experience. Incorporating exception handling into broader software design and development methodologies, such as Agile or DevOps, ensures alignment with organizational goals and promotes continuous delivery of high-quality software.