Before applying the type, all possible alternatives should be considered as overusing of Optional may lead to introducing new burdensome code smells. Our team work realy hard to produce quality content on this website and we noticed you have ad-blocking enabled. From what I can see, there are mostly two reasons mentioned for this: The first argument brought up is, that Optional is not Serializable. opt.flatMap(Widget::getName) // Won't work! Although the disadvantage is non-negligible, it is also not severe. Therefore, if solution 1 is used the calling code would look like this: if solution 2 is used, the calling code would look like this: if solution 3 is applied, I could use the code above or I could use the following (but it's significantly more code): So my question is: Why is it considered bad practice to use Optionals as method arguments (see solution 1)? I could see, that it's "more the Java way", to use null whenever some value is not present. rev2023.7.7.43526. Was there a cache hit that happens to be an empty collection? So, IMO discussion above shows, that even though mostly we can survive without nullable arguments, but sometimes it is not really feasible. You don't chain ofNullable and orElseThrow. Another use case would be to sequence multiple operations together. What could cause the Nikon D7500 display to look like a cartoon/colour blocking? It's a lot harder to ignore Optional than it is to ignore an annotation that you will only notice if reading the docs / source or if your tooling can catch it (static analysis can't always determine nullability correctly). That change makes client code much simpler and easier to read. Can't return values and fields be null as well? Assuming you have something like the following: You could write a function like this that would seem to fit your use case: Thanks for contributing an answer to Stack Overflow! The whole thing is worth a watch, but he addresses Optional<T> as an argument here: . Making statements based on opinion; back them up with references or personal experience. Microservices with Spring Cloud Kubernetes. But thats not the case. Java 9 & 10 add a lot of new methods for Optional, so upgrading will resolve a lot of your issues. The point is to avoid Optional fields in records. "Not handling null" could only realistically mean an exception is thrown. What does that mean? If you pass an Optional param you could favor do more than one thing, it could be similar to pass a boolean param. Why on earth are people paying for digital real estate? Extending the Delta-Wye/-Y Transformation to higher polygons. java8 - Optional- How to use it correctly? You can completely eliminate null from your code base by using Optional everywhere: not only in function return values, but also in function parameters, in class members, in array members, even in local variables. That said, in practice, I've rarely found using Optional as a field type or a parameter type to be an issue. Or lead to fewer issues? Connect and share knowledge within a single location that is structured and easy to search. findfirst I have coworkers that dont know Optional exists. one Java developer on Reddit. Now we come to the problem: if some of the arguments are nullable and others are not, how do we know, which one? The best post I've seen on the topic was written by Daniel Olszewski: Although it might be tempting to consider Optional for not mandatory method parameters, such a solution pale in comparison with other possible alternatives. I think routinely using it as a return value for getters would definitely be overuse. Approach 1: All arguments are nullable (according to java standrd, except primitive types). By rejecting non-essential cookies, Reddit may still use certain cookies to ensure the proper functionality of our platform. If my method is called and may return null, I'll return an Optional<> to make sure that null is handled but if I design the method and define that something cannot be null I can just use Objects#requereNonNull or if it can be null a simple check does the job. What's the difference between rxjava2's Maybe and Optional? And they depend on each other, but the results are optional. The isPresent ()-get () pair has a bad reputation (check further items for alternatives), but if. There may be a good answer to this, but this explanation of "why" doesn't cover it. returned from some other method): You're forced to wrap them in Optional even if you know they are not Empty. H2 Do modal auxiliaries in English never change their forms? Using an optional does not really enable you to write your method logic more neatly. Should Java 8 getters return optional type? But I recently moved from being a .net developer to a java one, so I have only recently joined the Optional party. sql Also it adds a bit of boilerplate, even thoough I personally find, use of Optional.empty() and Optional.of() to be not so bad. Instead of validation exception, they want the empty Optional. But eventually it comes down to a design decision that was made. Can I still have hopes for an offer as a software developer. localdate Subscribe for limitless reading experience: https://zivce.medium.com/membership, Foo getMeFoo(String fooId) throws IllegalStateException {, Optional calcAs(int a) {return Optional.of(a+1);}, jshell> Optional.of(1).flatMap(a -> calcAs(a).flatMap(b -> calcAs(b))), jshell> Optional.of(1).map(a -> calcAs(a).map(b -> calcAs(b))), getMeFoo("123").map(Foo::getXProp).orElse(DEFAULT_VALUE), thisOptional.isPresent() ? 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. For example I have a piece of logic which has 2 optional parameters. super T, ? In this cases performance penalty introduced by Optional may be really unwanted. That change makes client code much simpler and easier to read. graalvm With this in mind, I could use the following method signature and add a clear Javadoc comment to specify that the arguments may be null, hoping future maintainers will read the Javadoc and therefore always carry out null checks prior to using the arguments (solution 2): Alternatively I could replace my method with four public methods to provide a nicer interface and make it more obvious p1 and p2 are optional (solution 3): Now I try writing the code of the class which invokes this piece of logic for each approach. That way, if the Optional is empty, no WHERE param=y is performed. for an optional boolean, use Boolean. not throw any exception. I know that this question is more about opinion rather than hard facts. FreeBuilder, making the code short and tidy (relatively speaking - Java isn't known for its code compactness). In general: Optional unifies two states, which have to be unraveled. If Java did support true value types, then Optional would have been implemented as a single machine word, which would mean that the runtime overhead of using it would be zero. Since Java 8 appeared a few years ago, along with the introduction of Optional, I have seen many instances of misuse or incorrect use of Optional. localdatetime This adds the default Optional behavior to it. Let's make something perfectly clear: in other languages, there is no general recommendation against the use of a Maybe type as a field type, a constructor parameter type, a method parameter type, or a function parameter type. Which @NotNull Java annotation should I use? (Ep. I understand why this could be a problem. Can Visa, Mastercard credit/debit cards be used to receive online payments? Currently for orElseGet we can add a supplier of the return value type. Records are data carriers so we shouldnt add unserializable optionals. Why should Java 8's Optional not be used in arguments, How to map java.util.Optional to Something? I first retrieve the two input parameters from another object which returns Optionals and then, I invoke calculateSomething. Java Optional and best practices - Refactorizando Still, people have issues with Optional usage. ?, or at least you cannot in C# as it is currently implemented.). When youre certain that theres a value, then use Optional.of("something"). Optional is primarily intended for use as a method return type where there is a clear need to represent "no result," and where using null is likely to cause errors. But even there, it can be avoided. (function($){window.fnames=new Array();window.ftypes=new Array();fnames[0]='EMAIL';ftypes[0]='email';fnames[1]='FNAME';ftypes[1]='text';fnames[2]='LNAME';ftypes[2]='text';fnames[3]='ADDRESS';ftypes[3]='address';fnames[4]='PHONE';ftypes[4]='phone';}(jQuery));var $mcj=jQuery.noConflict(true); Optional deliberately doesnt implement the Serializable interface, an additional module that handles Optional fields, Injecting Spring Prototype bean into Singleton bean, How to bind @RequestParam to object in Spring. As seen in the previous example, you get optional and resolve with orElseThrow. RxJava2 will not allow publishing "null" values, I think that you should use Maybe and just don't publish "null". Youd have two cases shown by one value. I think routinely using it as a return value for getters would definitely be over-use. The wrapper method looks like this: So suppose you have a getter like this: String getName(). I think in such cases it might be useful to have optional as parameters. don't really understand the argument that Optional<> can be null itself. Having said that, there are libraries that eliminate it for you, e.g. Why is it considered "Bad Practice" to use Optional as the This optional is serializable compared to Javas optional. (-) Using Optional parameters causing conditional logic inside the methods is literally contra-productive. If you decide to go along this path, then you will need to be thorough, so you will have a lot of work to do. In this cases you could either use the boxed variant of int and long or you could use some magic constants to communicate a missing values in hope, the chosen value will never be a real result. "url" argument is nullable, then it becomes maybeUrl. And the only source for it is my thoughts and my experience (with Java and other languages). If a function is not doing additional computations on these parameters then using Optional might be simpler. To learn more, see our tips on writing great answers. Inside my own code all the variables must be not-null (but probably Optional<>). The Optional type is highly expressive in this situation and prevents automatic behavior from occurring. Required fields are marked *. Optional doesn't provide any additional value and only complicates client code, hence it should be avoided. So, if you would permit the pun, Oracle issued an oracle: Thou shalt not use Optional but for function return values. method return types where there needed to be a clear way to represent The idea here being whether you have got optional value or not will be internal detail of your function and will not be in parameter. Using Optional as parameters might be useful in some use cases which involves protobufs or setting fields in a configuration object. Please help us improve Stack Overflow. Optional as a parameter is bad practice. Not the answer you're looking for? In the original example posted, Optional is used as a method parameter so this is against Java best practices. Here's a bad practice sample: Optional<List<Item>> itemsOptional = getItems(); if (itemsOptional.isPresent()) { // do we really need this? What are the advantages and disadvantages of the callee versus caller clearing the stack after a call? Besides, Maybe is idiomatic in RxJava. Therefore forcing someone to take an existing object and wrap it in an optional is sort of pointless. 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. For more information, please see our I worked in a codebase like that for 2 years and we never got a NPE. Even so, we need to write our own serialization and not something java supports out of the box. in Kotlin. Scala does the same as well and no one thinks about nulls.
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java optional bad practices
java optional bad practices
