Set> classes = reflections.getSubTypesOf(Object. Unfortunately, we can't just use the code below with a normal Reflections object without specifying a custom configuration to allow Object scanning. Reflection on annotations is still very bad compared to Desktop Java, even on Android 6 and ART. It finds all classes, loops through them and gets the package name stored in a Set to avoid duplicates. Unfortunately, Androids performance did not get any better. PackageNameSet.add(classInstance.getPackage().getName()) Set> classes = reflections.getSubTypesOf(Object.class) filterInputsBy(new FilterBuilder().include(FilterBuilder.prefix("my.base.package")))) setUrls(ClasspathHelper.forClassLoader(classLoadersList.toArray(new ClassLoader))) setScanners(new SubTypesScanner(false), new ResourcesScanner()) Reflections reflections = new Reflections(new ConfigurationBuilder() List classLoadersList = new LinkedList() ĬlassLoadersList.add(ntextClassLoader()) ĬlassLoadersList.add(ClasspathHelper.staticClassLoader()) Once you have all of those, you have all of the packages.Īgain, it is not possible to know all the packages by just asking the classloader, unless you could somehow guarantee the class loader has loaded all of the classes (which it typically doesn't).Īs long as you don't need empty packages, something like this should work: /** Then you do a search of all the directories under each "starting point" that has a. a/src/share/classes/java/lang/reflect/AccessibleObject.java Wed Nov 28. The way to get the class path is: String classpath = System.getProperty("", null) test/java/lang/annotation/repeatingAnnotations/subpackage/Container.java. To "find" the directories, you will need to chop up the class path. Since you aren't using JAR files (and why not? they're really good!), you will have to scan directories. Edited as further details indicates JAR files are not being used. With this technique, you will discover all package names, even those that are not yet "in use". Syntax: The syntax for this method Class. Use the zip file handling routines to open the jar files, and read out the packages by directory name. We use two methods for this purpose as described below before moving ahead as follows: getDeclaredMethod () invoke () Method 1: getDeclaredMethod (): It creates an object of the method to be invoked. This means that if a class has not yet been loaded from a specific package, then it will be absent from the list. For example, URLClassLoader would not be implementable for 'http:' URLs because the HTTP protocol does not provide a standard way to retrieve the entries in a directory.īesides, there are few situations where a production application really needs to reflectively find all classes in a package.You really can't know every package name in the libraries by just using getPackages() as it only will list the ones known to the classloader. If the classloader API did include a method to give all classes in a package, it would limit the schemes that can be used for classloading. I understand that the omission is deliberate. It seems this is a massive fault in the java reflection API Notice that it should only work for classes found locally, getting really ALL classes is impossible. Firstly, we need to get a Method object that reflects the method we want to invoke. Let's create a simple class which we'll use for the examples that follow: 3. Bloom, Shadow, Reflection, MotionBlur Digital imaging. I would recommend that you find an alternative approach to the problem you are tying to address. 1 The code below gets all classes within a given package. In this short article, we'll take a quick look at how to invoke methods at runtime using the Java Reflection API. There is a lot more in the javafx.scene package, in subpackages as I call. One problem is that the ClassLoader API does not support iterating over all of the classes / packages that it could load. Then you use Class.forName() load the corresponding classes (trying to avoid initializing them), and use clazz.isAssignableFrom(subclazz) to see which of them are subclasses.īut this won't work in all cases. Basically, you need to map the package name to a pathname and use the File and/or ZipFile APIs to look for files in the relevant "directory" whose name ends with ".class". if your application's classes are loaded from local directories or JAR files. It is possible to do (messily) in some cases e.g.
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