This is a great example of how the proxy pattern can be used. copy deep shallow vs array javascript java object medium visitor pattern class diagram java example steps Yes. Good example, however, this solution has problems depending on the use case: What if A, B and C are supposed to be used beyond just calling M? Depending on the use case, it will be terrible and you would've been much happier by simply extending A, B and C. @akuzminykh I agree that adopted solutions depend on the use cases. If a creature's best food source was 4,000 feet above it, and only rarely fell from that height, how would it evolve to eat that food? Connect and share knowledge within a single location that is structured and easy to search. When adding a new disk to RAID 1, why does it sync unused space? What would the ancient Romans have called Hercules' Club? The example I have run into is a legacy library using a non-threadsafe collection that you just want to switch out. Once that's done, you don't need to handle the variable wrapIFC any differently than you would any variable initialized with new A(): You could also create a separate independent (abstract?) Asking for help, clarification, or responding to other answers. If the library developer adds a new function that returns an A,B,C, then it too must be wrapped. Thanks for contributing an answer to Stack Overflow! Why can't I define a static method in a Java interface? Find centralized, trusted content and collaborate around the technologies you use most. class or interface, that you call instead of calling method() passing in your instances. In the twin paradox or twins paradox what do the clocks of the twin and the distant star he visits show when he's at the star? In such a case one can't call M4 if it's initialized with the variable type as the interface though. What if A has M4 but B doesn't? To learn more, see our tips on writing great answers. Announcing the Stacks Editor Beta release! instrumentation or wrappers as suggested by @Scratte), depending on what you. Data Imbalance: what would be an ideal number(ratio) of newly added class's data? Depending on the library's use of other dependencies and build complexity, this may be non-trivial. Interesting case where A has an M4, but B doesn't. Should I remove older low level jobs/education from my CV at this point? Will it be nice? I use a library with an interface, IFC, that is implemented by three classes, A, B and C. I want to make my own implementation of the method M, that is defined in IFC, and implemented in A, B and C, that should override the corresponding methods in A, B and C. In Java, you implement, not extend, an interface and you can only extend one class.

This question goes over this technique in some detail, and highlights one library, HotSwapAgent that can do this. Extend three classes that implements an interface in Java, How APIs can take the pain out of legacy system headaches (Ep. There are libraries that claim to be able to do this. In this situation, achieving this through regular java code is, as many pointed out, impossible. Why does KLM offer this specific combination of flights (GRU -> AMS -> POZ) just on one day when there's a time change? This leads me to the conclusion that what I want to do is not possible. Java Class that implements Map and keeps insertion order? You can then use that to wrap instances of, looks like an x-y-problem: for some reason you didn't elaborate on, you want to change the specification of existing interfaces/classes (that is IFC, A, B, C) - which can't be done, as you know ;) There might be options (f.i. Essentially you will have to make an abstraction layer above whatever API the library is providing. How do I test a class that has private methods, fields or inner classes? Trending is based off of the highest score sort and falls back to it if no posts are trending. rev2022.7.21.42639. Their utilization may have an outsized impact on build complexity and maintenance of the code you are writing. Change a method at runtime via a hot swap mechanism. On the question of passing them to other methods of the library, then the, Glad that you see the problems too .. And this is where the "Needs details or clarity" comes into place. ;) But as I said in my. All instances of returned or passed A,B,C must be wrapped or unwrapped. In M you'd do your stuff and then call M of IFC, where IFC can be A, B or C. So you'd wrap all instances of A, B and C in such a class, which will avoid extending A, B and C. The advantage of this is that you only have to account for it when initializing your classes by wrapping them: IFC wrapIFC = new IFCWrapper(new A());. How should I have explained the difference between an Interface and an Abstract class? What if you pass instances of A, B and C to other methods of the library? I will assume the situation is like mine, and that you only have access to a jar, but no source and that you want to change internal usage of M() as well. Using this simplified implementation of the library, using method() instead of M(): You'd write a class that has M and a field for IFC. Making statements based on opinion; back them up with references or personal experience. I picked the option to pass in any extra stuff I want for this example using a Runnable: I have run into a situation like this before. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. "implements Runnable" vs "extends Thread" in Java. You can now choose to sort by Trending, which boosts votes that have happened recently, helping to surface more up-to-date answers. When to use: Java 8+ interface default method, vs. abstract method, JavaScript front end for Odin Project book library database. However, if the code is on your computer, there are two techniques outside of the boundaries of normal java development you can use. Did Sauron suspect that the Ring would be destroyed? Is there another way? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. One possible solution, if you truly want to replace every instance of M(), without making your own classes, is to swap the methods at runtime. What if A, B and C have not just M but also M1, M2 and M3? At runtime, find all classes in a Java application that extend a base class. And then two identical classes for B and C, each with an identical myM-method, but this feels really clumsy and ugly. Even worse, this abstraction layer must be maintained. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, I don't see an alternative to extending A, B and C. Anyways, if, Maybe you want to use a proxy/adapter that overrides the one method and delegates all the others to an underlying instance. Can a human colony be self-sustaining without sunlight using mushrooms? Another solution is to decompile the library's jar, change the offending method and recompile it. You'd need to write much code beyond the simple usage of a single method M. Will it work? The downside is that you'll have to remember to call this every time you'd want to call method() on your instance. Why do the displayed ticks from a Plot of a function not match the ones extracted through Charting`FindTicks in this case? Is there a political faction in Russia publicly advocating for an immediate ceasefire? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Why do many Collection classes in Java extend the abstract class and implement the interface as well?

Can a timeseries with a clear trend be considered stationary?

Is there a difference between truing a bike wheel and balancing it? In a large library this may mean wrapping hundreds of functions.

If the library updates, you must repeat the process. Why did the gate before Minas Tirith break so very easily? While proxy/adapter is all well and good if you're just going to use A, B and C external to the library, you might want to replace M() as called from A,B,C when used internally as well. The ramifications of this at scale may not be apparent at first glance though.

Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. Show that involves a character cloning his colleagues and making them into videogame characters? Tannakian-type reconstruction of etale fundamental group, Sets with both additive and multiplicative gaps. 465), Design patterns for asynchronous API communication. How should we do boxplots with small samples? You are then also in a situation where you must maintain that new altered jar.