Also, note the unnecessary use of a boolean variable (somethingKnown) only to use it in the break case, and then fall into a return statement. Bloaters can be big methods or classes, primitive obsessions, data clumps, or long parameter lists. I've been guilty of practicing many of these bad habits myself. And if you want examples of the stinkiest code imaginable, How to Write Unmaintainable Code is a good place to start. All pages . The Long Parameter List is when you have a method that has more than 3 parameters. There’s also more subtle duplication, when specific parts of code look different but actually perform the same job. Over a million developers have joined DZone. As you are probably aware, copy & pasting code is a blatant violation of the DRY principle (“Don’t Repeat Yourself”). Let's start with a core question – why analyze source code in the first place? Creating these fields in the class has no value most of the time because they are just used for this specific calculation. Determining what is and is not a "code smell" is subjective, and varies by language, developer and development methodology. when creating UIs without using a designer tool that generates the code). 2. Java is a strongly typed language. java eclipse-plugin code-smells smells-agllomeration Updated Dec 27, 2018 I'll leave the other categories for a future post. Published at DZone with permission of Ana Nogal, DZone MVB. Today in this article we covered Code Smell aspects of “Primitive Obsession” and also discussed remediation and refactoring recipe to address these smells. In the last post, Code Smells - Part I, I talked about the bloaters: they are code smells that can be identified as Long Methods, Large Classes, Primitive Obsessions, Long Parameter List and Data Clumps. Bloaters are code, methods and classes that have increased to such gargantuan proportions that they are hard to work with. But limiting them to a fixed number of lines is a style guide smell and may lead to new code smells: sometimes there are reasons for longer functions (e.g. Here you can: first, make one of the hierarchy refer to instances of another hierarchy. Except in this particular real-life case, there was virtually no documented API. But you should consider it a smell too if you find a sequence of ifs. This doesn’t mean you have to make changes in your code: there are occasions where these code smells are ok, but I think it’s important for us to detect them and know exactly why they are there. Why are switch statements bad? People, do unit test your code. All Loops Are a Code Smell. (too many getters/setters) From Java Code Conventions 1999: One example of appropriate public instance variables is the case where the class is essentially a data structure, with no behavior. You can just copy the Java folder and translate all of them into your language of choice. Remember identifying a code smell doesn't mean that you have to get always rid of it: it's a trade off. This is the case when you find yourself changing the same class for several different reasons. ... Other examples of safe side-effects are writing to a file, database, or message queue. So while talking to David, he asked me: and what happens if I encapsulate the switch into a method, is it acceptable then? In this case, it makes sense to have all together. In this post, I’d like to dissect the many “smells” (see Martin Fowler’s book) that a particular Java class was emitting, how this could have been avoided, and the many anti-patterns encountered. The quick definition above contains a couple of subtle points. Here are some tips for avoiding confusing code: You remember when you were a kid and you were asked to “spot the difference” between two pictures that seemed identical? One of the simplest scenarios in which vulnerable code can manifest itself â€“ which can usually be spotted immediately â€“ goes hand in hand with the copying of buffer data using functions such as strcpy, without performing any check on the size of the copy. Hmm, this case makes me think of "lack of communication" between members of the same team because this happens when we have two classes that do the same thing but have different names for their methods. Java Bharat Savani December 27, 2018 August 9, 2020. The chosen technologies (REST, Java, MongoDB) were actually valid technical choices for the problem at hand. Optional value means that either the value might or might not be present. This all depends on whether the original class still has any responsibilities. But it's really easy to refactor and have a cleaner code too. If limit is 1, do you actually get only one result? The. Can you spot the similarities? Let's take a look at the method createXMLRCPRequest and see if we can call the others from there. When rushing to meet dea… So you apply the Open/Closed Principle. Hello, world! An issue can be logged on a source file or a unit test file. Oh boy, how nervous I was! don’t avoid safety checks in your code by indiscriminately “swallowing” exceptions. This makes it very difficult to mock the call, or the database query, or to construct a set of data-driven tests, which would have enabled us to test the data transformation and view generation logic in the method under several different scenarios. Optional class encapsulates the optional value. Next. This class implements a hash table, which maps keys to values. It represents immutable container of non-null reference to T or nothing at all. Usually these smells do not crop up right away, rather they accumulate over time as the program evolves (and especially when nobody makes an effort to eradicate them). It all looks ok. If it only affects how you select a behaviour of the class then the Strategy Pattern is a better choice. Sometimes duplication is purposeful. This kind of code smell happens when you have a big method. What do I mean by this? Let’s discuss the types of code smell and some tips to remove it from your code much cleaner, clear, and simpler to understand. This will permit you to move the duplicated methods or fields to a common class. This means that when you make a small change in a class, you have to go and change several classes at the same time. Feature Envy Example In the Customer class below, the method getMobilePhoneNumber() provides a North American-formatted mobile Phone number: With Feature Envy; Without Feature Envy; public class Phone { private final String unformattedNumber; But most importantly, because none of the methods invoked is static, it is much easier to construct a test context that is easy to reason about. Make your Java code smell nice and fresh. If so, try Extract Superclass and make the original classes the subclasses. As a programmer, I've seen a lot of poor practices, not just around code, but also around teamwork skills. It’s worth mentioning that the same exact pattern (navigating nested maps according to sequence of strings) was scattered all over the 600+ lines of code of this class. You can find a good reference to all of then in Refactoring.com. When serving such a complex object back, you would want to test it under several different scenarios and ensure that the returned object conforms to the API documented specs. Duplication usually occurs when multiple programmers are working on different parts of the same program at the same time. Then I passed it on to my colleagues as a “Java Puzzler” and their guesses were wildly confused, too. Determining what is and is not a code smell is subjective, and varies by language, developer, and development methodology. So, you’d be forgiven for coming up with a utility method like the one I hacked together in less than 10 minutes to replace the abomination above: The result is that the sequence of lookups (which, again, when first encountered looked like a riddle wrapped in an enigma) now looks something like: This is still not as clean as I’d like it to be, but I mostly blame Java for lacking a factory class similar to Scala’s Lists: Also a quick note the anti-pattern of using a try-catch block to filter out potentially valid code paths, and avoiding writing null and key-existence checks. Types of Code Smells. Too bad they then proceeded to get it spectacularly wrong with a bloated (and unmanageable) data schema and an even worse Java implementation. The term was popularised by Kent Beck on WardsWiki in the late 1990s. I'm SourceMaking. Java 1.4 provided programmatic access to the stack trace through the introduction of StackTraceElement class This fixed the “missing abstraction” smell! This also limits the possible permutations that need to be tested. Since they’re working on different tasks, they may be unaware their colleague has already written similar code that could be repurposed for their own needs. The above shows part of the vulnerable code on the University of Washington’s IMAP server, which was corrected in 1998. Let the compiler and the JVM do the legwork, and catch your (and others’) mistakes. If you find your switch statement replicated and each replication has different behaviour, then you cannot simply isolate the switch statement in a method. Opinions expressed by DZone contributors are their own. Well, I have the rule that with more than five lines, you should, at least, look at it again. Sometimes we see that when we receive an object, and instead of passing it all we pass some of its data. KentBeck (with inspiration from the nose of MassimoArnoldi) seems to have coined the phrase in the "OnceAndOnlyOnce" page, where he also said that code "wants to be simple". Last weekend, I was at SoCraTes Canaries and I gave my first talk ever about code smells. Here's the code in Objective-C: Wow! There are five categories of code smells: Today I'm going to talk about Bloaters. This code smell is a little tricky to detect because this happens when a subclass doesn't use all the behaviours of its parent class. A deep understanding of issues related to distributed computing, a capacity for critical reasoning and abstract thinking, and an understanding of operational issues related to scalable systems — these are critical these days for becoming a great software developer. Learn to code for free. The Smell: If Statements. A code smell is a surface indication that usually corresponds to a deeper problem in the system. And if you want to make fun of my code, just head to my github repositories, I’m sure there’s still plenty of smells there (but, hopefully, also a few nuggets of good code that will hopefully inspire you!). You can apply here the Visitor pattern too. The only way you could have found that out, though, would be to run the actual server in debug mode, then execute the API call from a client and see what comes up at the other end. Secondly, it’s clear what the various parameters are from their names. And it is inside a ViewController class, so this should definitely be extracted into a service class, so we have a correct separation of concerns. It took me the best part of an hour to reverse-engineer the following method. But, as Sandro told me before, the right number of lines is just enough lines so a method only does one thing (and so it conforms to the 1st principle of SOLID the Single responsibility principle. Although there are more than a hundred of code smells. Marketing Blog. In fact if you avoid it, then your code will smell! This project is an Eclipse plugin that aims to collect code smells from Java projects using only command line tools. Close Preview. Extract all methods and fields from the subclass and parent class and put them in a new class. Then you can split the method into several methods within the same class. in code smell, code smell examples, design pattern, design patterns in java, Inheritance forest, java 5, java 6, java design pattern, strategy design pattern in java, strategy pattern in java - on April 03, 2017 - … There is a good reason for this. CODE SMELL/ BAD SMELL Types of Code Smell Duplicate Code Example 1 extern int a[]; extern int b[]; int sumofa = 0; for (int i = 0; i < 4; i + +) sum += a[i]; int averageofa= sum/4; —————- int sumofb = 0; for (int i = 0; i < 4; i + +) sum += b[i]; int averageofb = sumofb/4; Extract method int calc-average(int* array) int sum= 0; for (int i = 0; i < 4; i + +) sum + =array[i]; return sum/4; Because when a new condition is added, you have to find every occurrence of that switch case. And so on. Make this new class the SuperClass, from whom the subclass and parent class should inherit. Try and make the intent of your method(s) obviously clear to the readers of your code. A list of language agnostic rules from the Clean Code book, with commentaries.. W riting is the best technique to memorize things. For instance: The size of code decreases, confusing coding is properly restructured. If you let through potentially erroneous conditions, you will make it exceedingly difficult to find out root causes of unexpected bugs. My hope is that by reading this post, you will avoid making the same mistakes, and folks like me will not be required to come over and fix your stinkin’ code! Interactive examples. Sad as it sounds, hitting the DEL key on that pile of crap was the high point of my day. Here’s an example of what not to do: a class was implemented to serve a particular API call which — in response to a client query — would serve a very complex object, with deeply nested sub-objects, all couched in a mix of business logic and UI-related data. If not, it will tell you so, then return null — and let us gloss for a moment on the fact that it requires the caller to pass in the id only to use it in a debug statement. For example, why assign the value of a flag that indicates whether the trip is “on route” to a flag that indicates whether that elusive something was found? Before you ask if some technique is a "code smell," ask yourself what the consequences to your specific project would be, if you used the technique. In fact, not only there was also no unit testing, but the class was (and probably still remains) untestable. Here the best refactoring technique is to use Replace Method with Method Object, which will extract the method into a separate class. You will add another method like this: See the repetition of the switch? Avoid shortcuts that will render the logic of your code obscure to other developers. I like to think that a code smell is something that makes your developer instinct cry out to you, and you just know that something is wrong. See README file in the "interactive" folder. In short: And, yes, your code will look nicer and your self-respect will improve too. A code smell is a surface indication that usually corresponds to a deeper problem in the system. In the end, we figured out that this method was entirely pointless, and we removed it entirely. New developers joining the team will have a less steep learning curve. In computer programming, a code smell is any characteristic in the source code of a program that possibly indicates a deeper problem. Follow agreed-upon naming conventions, clear arguments lists, clear algorithm implementations, and help your co-workers do the same. Snappy Answers to Stupid Programming Questions. You should use the Strategy approach when the Type Code affects the behaviour of your classes. This case is when we use primitives instead of value types for simple tasks. Overview SonarLint is an open-source IDE plugin for Eclipse and IntelliJ that performs static analysis on Java code. And, for God’s sake, avoid concatenating strings. Not to mention, it’s pretty awful to look at. But for the sake of the brevity, let's focus on how can we refactor this big method. 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