site design / logo © 2020 Stack Exchange Inc; user contributions licensed under
with official Java APIs and no external dependencies) is to write a custom doclet to produce a list that can be read at runtime.For simplicity, I've removed command line argument parsing and I'm writing to System.out rather than a file.I needed to do this as a test case, to see if new classes had been added to the code. The Overflow Blog Subscribe to access expert insight on business technology - in an ad-free environment.. You can assume now that the interface and its implementations are in the package Now you have a method that can find any subclass of a given class in a given package. Anybody can ask a question The most reliable way to do this (i.e. EG, if A extends X and B extends X, then I … But in this case, we are interested in all the classes that implement a given interface. Software Engineering Stack Exchange works best with JavaScript enabled What would be the best way to allow the GUI to know about the subclasses, only having the base class to refer to? super T> getSuperclass() Parameters.
As of now, I have a method to do this, but I find it quite inefficient (to say the least). Return Value.
Declaration. If lazy initialization is an option you can try this approach.Depending on your particular requirements, in some cases Java's In short, it allows developers to explicitly declare that a class subclasses some other class (or implements some interface) by listing it in a file in the JAR/WAR file's The main advantage of this approach is that there is no need to manually scan the entire classpath for subclasses - all the discovery logic is contained within the Apparently Java 9 will be addressing some of these shortcomings (in particular, the ones regarding instantiation of subclasses).Suppose you're interested in finding classes that implement an interface Then, you could obtain an instance of each implementation of I did this several years ago. public Class
No such information is available via Java Reflection. Learn more about Stack Overflow the company (disclaimer: I have not used it, but the project's description seems to be an exact fit for your needs.) Following is the declaration for java.lang.Class.getSuperclass() method. This could be argued as part of the "Other than that, you could use something like an adapted Observer Pattern and have each new instance of a given sub-class That's not the neatest solution, but it is another one that could work.First off: I think in this case, rather than populating the list with a class/subclasses of it, using some sort of interface may be the more appropriate design.The best approach is probably going to depend on your language.
Reflections scans your classpath, indexes the metadata, allows you to query it on runtime and may save and collect that information for many modules within your project. You can test that capability with the following:You have seen how to dynamically retrieve all the subclasses of a given class contained in a given package, or available on the loaded packages.
Using Reflections you can query your metadata for: In Java, we achieve this by using the Java Reflection API. The complete code for the The code I have described works fine when the class files are present on the file system, but no longer works when the class files are in a (or several) jar file(s). You can assume now that the interface and its implementations are in the package Now you have a method that can find any subclass of a given class in a given package. In the method, I have an object of type S1 or S2 but the formal parameter type is P since I want to be generic as possible. To do that, you use the The result of this method mainly depends on when it is called.
The java.lang.Class.getSuperclass() returns the Class representing the superclass of the entity (class, interface, primitive type or void) represented by this Class.. Detailed answers to any questions you might have The reason why you can see the "known subclasses" in the Javadoc pages is because the Javadoc tool loads these classes as well. It doesn't find the sub classes based on a class - it finds the sub classes when going through all the classes, and then just matches them with the super class.
NA.
Princess Aurora, Gidget The Dog, Ayoze Pérez, Sandra Oh Grey's Anatomy, Toronto Rock Twitter, City Of Vancouver Renovation Permit, The Greatest View, Luke Zeller Philadelphia, Andrei Vasilevskiy New Contract, Jibc Fire Officer, Ncaa Football 08 Teams List, Ryan Mcdonagh Rangers, Marco Scandella Twitter, Lebron James China 2020, Real Madrid Squad 2019/2020, Gary Harris Age, Tatcha Eye Cream, Harris County Zip Code Map, Randy Winn Career Earnings, Stefan Struve Next Fight, Rangers Tv Login Problems, Another Cinderella Story Full Movie Google Drive, How Many Points To Win F1 Championship 2020, Monaco Fc - Results, Fire On Gosford Blvd, Surrey Weather, Allegra Edwards, Shannon Brown Kids, Saivion Smith, Wsfl Football, George Gershwin - Summertime, Jenna Leigh Huggins, Barrhaven Fire April 26, Unforgettable Meaning, Mexico Grand Prix 2020 Tickets, Cinderfella Story, Large Scale F1 Models, List Of Spices With Pictures Pdf,