MethodAnnotationsScanner is not getting configured unless there is at least one class using the annotation

[sivaprasadreddy]

I am using reflections:0.9.12 and I want to scan for Constructors which have some annotation, let's say @Autowired.

public class UserService {
	private UserRepository repository;

	public UserService() {
	}

	@Autowired
	public UserService(UserRepository repository) {
		this.repository = repository;
	}
}

Reflections reflections = new Reflections(new ConfigurationBuilder()
		.setUrls(ClasspathHelper.forPackage("com.sivalabs.myapp"))
		.setScanners(new MethodAnnotationsScanner()));

Set<Constructor> constructorsAnnotatedWith = reflections.getConstructorsAnnotatedWith(Autowired.class);

This code is working fine if there is at least one class using @Autowired annotation. But if there is no class using @Autowired annotation in the package com.sivalabs.myapp then following exception is being thrown:

Exception in thread "main" org.reflections.ReflectionsException: Scanner MethodAnnotationsScanner was not configured
	at org.reflections.Store.get(Store.java:39)
	at org.reflections.Store.get(Store.java:61)
	at org.reflections.Store.get(Store.java:46)
	at org.reflections.Reflections.getConstructorsAnnotatedWith(Reflections.java:515)

Expectation: MethodAnnotationsScanner should be registered even when there are no classes using any particular annotation and when reflections.getConstructorsAnnotatedWith() is called it should return empty result.

[dota17]

I wrote a test case according to your description and tried it, it can work without any exception. But when I change the parameter of the function forPackage() to wrong, the error message is the same as yours. So I think your function parameters may be wrong.

[sivaprasadreddy]

The package I used ("com.sivalabs.myapp" ) is correct and I have classes exists in that package also. But even if the package name given for forPackage() doesn't exists, it should return empty Set instead of throwing exception.

[dota17]

Yes, this exception will occur when annotations are not used at all. If I use other annotations in another class, this exception will not occur. I will try to figure this out.

[dota17]

In reflections:0.9.12, if your scanner scans nothing from the class file, the storeMap will be empty. As a result, when reflections.getConstructorsAnnotatedWith() is called, an expection will be thrown here:

reflections/src/main/java/org/reflections/Store.java

Line 43 in 9a1ac08

Map<String, Collection<String>> mmap = storeMap.get(index);

But this problem has been fixed in the latest master branch. When the class Store is initialized，storeMap will get an initial value。See:

reflections/src/main/java/org/reflections/Store.java

Line 28 in 9a1ac08

protected Store(Configuration configuration) {

[veselov]

Bump. Is it possible to make a release with this fix?

[ronmamo]

apologize for this inconvenience !

scanner was not configured exception - as @dota17 mentioned, this is a known issue in 0.9.12, a simple workaround is to check if the getStore() contains index for the scanner before querying. next version 0.10 fixes this.

[ronmamo]

fixed on 0.10