Please help us improve Stack Overflow. Our intention was to provide a limited mechanism for library method return types where there needed to be a clear way to represent no result, and using null for such was overwhelmingly likely to cause errors. How to add a specific page to the table of contents in LaTeX? You don't chain ofNullable and orElseThrow. In case when theres no element to return, an empty instance is superior to empty Optional and null as it conveys all necessary information. intention when adding [Optional], and it was not to be a general clumsy. Reasoning that might apply to other Maybe types, or other languages, is probably not valid here. Therefore forcing someone to take an existing object and wrap it in an optional is sort of pointless. Understanding Why (or Why Not) a T-Test Require Normally Distributed Data? Our intention was to provide a limited mechanism for library method return types where there needed to be a clear way to represent "no result", and using null for such was overwhelmingly likely to cause errors. (Ep. There are almost no good reasons for not using Optional as parameters. Newer Java versions solve a lot of issues for Optional. Guava Optional has the or method for lower Java versions if that's what you need. As far as I know, they were voted out of official Java standard (and I don't know if there are any plans to try again). In Java, the 'Optional' class is a container object used to represent the presence or absence of a value. Anyway, I said you could favor, of course there are exceptions you may use it, its up to you, just use it carefully, thats all. ChatGPT) is banned, Testing native, sponsored banner ads on Stack Overflow (starting July 6). I don't see any good reasons against using Optionals as arguments (provided you don't want to use method overloading). Required fields are marked *. Even so, beware that Guava Optional and Java's Optional aren't interchangeable. Optional does not have to add overhead, it only does so in Java. However, as for calling the constructor, client code can become a little bit clumsy. By using Optional as the type of a member variable, you can also communicate, that this field is not always present and have much less trouble with null values and checking for them. Optional doesnt provide any additional value and only complicates client code, hence it should be avoided. Why is it considered "Bad Practice" to use Optional as the Instead of having to go through multiple steps to retrieve a value, we can use lambda expressions to chain operations and obtain the value. Optional isnt serializable so using in records makes no sense. Edit: Approach 5: I used this one recently, when I could not use Optional. In the original example posted, Optional is used as a method parameter so this is against Java best practices. For example, you probably should never use it for something that returns an array of results, or a list of results; instead return an empty array or list. The wrapper method looks like this: So suppose you have a getter like this: String getName(). What is the significance of Headband of Intellect et al setting the stat to 19? I'm not sure what ambiguity there is @user2986984. Before Java 8, receiving a null value from a method was ambiguous. Optional solves both problems by providing a convenient way to force the user of the method to check its self-explanatory output. And avoid the value!=null Optional trait. thisOptional : secondChoice. Why? Are we using ofNullable in the wrong way? For your example, where each parameter is optional, I would suggest to change the calculation method into an own class like follows: This is because we have different requirements to an API user and an API developer. Not as object fields. There may be a good answer to this, but this explanation of "why" doesn't cover it. Instead of providing clarity, the factory methods of the Optional Is the part of the v-brake noodle which sticks out of the noodle holder a standard fixed length on all noodles? Hence better suited for result than input, for the complexity of the data flow. Archived post. What could cause the Nikon D7500 display to look like a cartoon/colour blocking? As seen in the previous example, you get optional and resolve with orElseThrow. That doesnt mean you should use it instead of a null check. Whenever possible, avoid using .isPresent() and chain the operations instead. You can't just simply implement the Serializable interface and are done. And that's not the use case for this tool. Doing it the other way around (having the caller provide the . the callee, it should be responsibility of the caller to check the for an optional boolean, use Boolean. If I have a method with one or two optional arguments I try to redesign it using overloads, inheritance etc. session This seems a bit silly to me, but the only reason I can think of is that object arguments in method parameters already are optional in a way - they can be null. First of all, if you're using method 3, you can replace those last 14 lines of code with this: int result = myObject.calculateSomething(p1.orElse(null), p2.orElse(null)); The four variations you wrote are convenience methods. Most developers use maps and thats fine for most cases. Java and dev lifestyle stories. I believe the reson of being is you have to first check whether or not Optional is null itself and then try to evaluate value it wraps. What is more, Optional deliberately doesnt implement the Serializable interface, which essentially disqualifies the type as a member of any class that relies on the mechanism. Lets see an example: The previous one would be a better option; you can see that the code is quite similar, but computationally speaking, youre creating an unnecessary wrapper, which is more costly for the compiler. I think routinely using it as a return value for getters would definitely be over-use. (I'm aware the designers of Optional intended it to only be used as a return type, but I can't find any logical reasons not to use it in this scenario). After all, we When a method can accept optional parameters, its preferable to adopt the well-proven approach and design such case using method overloading. The disadvantages are already mentioned in other comments, the worst of which is (IMO) performance penalty. Also it adds a bit of boilerplate, even thoough I personally find, use of Optional.empty() and Optional.of() to be not so bad. In real life there are different situations. If we want to verify the absence of the result, each collection has the isEmpty() method and in case of arrays, the length property can be used. The isPresent ()-get () pair has a bad reputation (check further items for alternatives), but if. All "object"-variables are nullable and all primitive-types are not. The way they are treated by different systems are not uniform. What's the use case for Optional flatMap? After all, theyll need to meet the promise of Codes like a class(Optional), works like an int.. Regarding the last paragraph, my convention is a post-fix. Was it a cache miss? 2. That way, if the Optional is empty, no WHERE param=y is performed. They are computationally less expensive, simplify the code, and are considered best practices: In this post, we have tried to analyze the options we have with Java Optional and best practices to make better use of Optional. Composing functions that feed on, or whose computation should be reported to, the real-world (so called side effects) requires the application of functions that take care of automatically unpacking the values out of the monads representing the outside world (State, Configuration, Futures, Maybe, Either, Writer, etc); this is called lifting. Not great practice, as youre using an empty Optional to swallow the error. English equivalent for the Arabic saying: "A hungry man can't enjoy the beauty of the sunset". What does "Splitting the throttles" mean? Theres nothing wrong with Optional that it should be avoided; its just not what many people wish it were, and accordingly, we were fairly concerned about the risk of zealous overuse. Note that you'd have to have the right tooling to actually identify it, and it'd provide more of a static check than an enforceable runtime policy, but it would help. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, If you used optionals, wouldn't you have to check that the optional passed as a parameter isn't, Yes, but it would make it obvious to some one else maintaining the code in the future that the parameter can be empty/null, therefore potentially avoiding a null pointer exception in the future. Mixing these two levels of abstraction doesn't facilitate legibility so you're better off just avoiding it. Otherwise, it's full. So if you "shouldn't" use Optional as a parameter type in Java, the reason is specific to Optional, to Java, or to both. I've read on many Web sites Optional should be used as a return type only, and not used in method arguments. On the one hand, in the aforementioned Stack Overflow post, Brian Goetz left no doubt the type isnt suitable for accessors. I'm struggling to find a logical reason why. I'd like to point out 10 antipatterns for the coding process itself; half are in this article, and the worst offenders are in the next article, to be published in Java Magazine soon. Also it adds a bit of boilerplate, even thoough I personally find, use of Optional.empty() and Optional.of() to be not so bad. And the only source for it is my thoughts and my experience (with Java and other languages). I really hope to understand, why this decision was made in Java. Optional of will throw NPE if the value is null. Does "critical chance" have any reason to exist? Using Optional just to check for the presence of a value is Bad Code: // BAD CODE -- just check getEmployee() != null Optional<Employee> employeeOptional = Optional.ofNullable(employeeService.getEmployee()); if(employeeOptional.isPresent()) { Employee employee = employeeOptional.get(); System.out.println(employee.getId()); } Passing a null Optional reference can be considered a programming error (because Optional provides an, I'm sorry, but I cannot agree with the argument "wasn't designed" or "somebody recommends against it". Such construction reminds the user of an Optional object that the situation when theres nothing inside must be handled appropriately. The ArrayList implementation for example does the same as its contents aren't guaranteed to be Serializable. When a program fails due to input issues, it's often a result of poor programming practices. How much space did the 68000 registers take up? Stephen Colebourne, mostly known as a principal contributor of Joda-Time and the JSR-310 specification, proposed on his blog post to keep nullable fields inside of a class, but wrap them up with Optional when they leave the private scope through public getters. You could do a simple null check instead. All rights reserved. date However the specification is complete and verbose, there is still a chance that the user is either unaware of it or just lazy to deal with it. pattern Another use case would be to sequence multiple operations together. This advice is a variant of the "be as unspecific as possible regarding inputs and as specific as possible regarding outputs" rule of thumb. Miniseries involving virtual reality, warring secret societies. Valhalla wont enable using optional as a field. Apparently Optional is only "a limited mechanism to represent a method may have no result". But in this case, I don't see a reason, why it should only be limited to the return type of methods. Although it might be tempting to consider Optional for not mandatory method parameters, such a solution pale in comparison with other possible alternatives. Guide To Java 8 Optional But I recently moved from being a .net developer to a java one, so I have only recently joined the Optional party. This adds the default Optional behavior to it. Now in a codebase that wants to use solution 2 we get NPE every couple of weeks, so it can't be better, sorry. You only return the Optional if it's absent from the fooService. Before applying the type, all possible alternatives should be considered as overusing of Optional may lead to introducing new burdensome code smells. While these aren't really official yet, you can use JSR-308 style annotations to indicate whether or not you accept null values into the function. scalability Extending the Delta-Wye/-Y Transformation to higher polygons. Now we come to the problem: if some of the arguments are nullable and others are not, how do we know, which one? I first retrieve the two input parameters from another object which returns Optionals and then, I invoke calculateSomething. java8 - Optional- How to use it correctly? processing of huge amounts of data, so that total execution time is very large, or situations when throughput is critical). But we did have a clear intention when adding this feature, and it was not to be a general-purpose Maybe type, as much as many people would have liked us to do so. Of course, there might be cases, when it is necessary to write your own auxilary function that works on Optional. It is often used as a method return type to indicate that a method may return a value, or it may return 'null'. This operator enables us to return Optional instead of some value. So we check all of them. Heres a bad practice sample: As long as the getItems() method returned the unwrapped list instance, client code could get rid of one condition check and simply iterate over the collection. Orchestration Why should Java 8's Optional not be used in arguments, How to map java.util.Optional to Something? Save my name, email, and website in this browser for the next time I comment. So, the question that it ultimately boils down to is: Do you want perfect clarity and type safety in your code, or do you prefer maximum performance? If not, I use Optional as argument types and/or field types. Your methods should probably never return Optional unless it's necessary to use them in functional programming. Using the boxed variant of primitives seems like the better alternative here, but it is not optimal, since boxing not only costs performance, it will also give you confusing error messages, if Java tries to unbox a null value. If I cannot find the solution in reasonable time, I start thinking, if the performance is critical (i.e. Youd then look at Optionals as a mere tool for mapping further. The idea is simply to use naming convention for method arguments and class variables. Surprisingly, one of the more controversial topics amongst all the added features is the Optional class. I believe that for high-level languages, (of which Java certainly aims to be one,) this question was settled a long time ago. eager findfirst guava Brian Goetz said it best when he said this: The reason Optional was added to Java is because this: Irrespective of Java 8, Use old school method overloading technique to bring clarity and flexibility, suppose you have following method with two args, in case you want to add additional optional parameter then overload the method, A good example were Optional as arguments would be nice is JPA Repositories.
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