CODEWITHSUNDEEP
java
Abhishek Singh
Abhishek Singh

Reputation: 67

URLClassLoader in java

I am working on a project which requires loading classes at Runtime, so I did some research and found out that I need to use Custom Class Loader. I implemented my own custom UrlClassloader and provided it with the url of my jar files, it worked correctly and the class files got loaded. I have read the java doc for URLClassLoader and they have mentioned clearly that any URL that ends with "/" is assumed to refer to a directory so does it mean that if I have multiple jar files in the directory my classloader will all load all of them, I tried it but it didn't work. so what's the logic behind that. please explain I am very much confused. what if I want multiple jars to be loaded at runtime from a directory?

Upvotes: 1

Views: 1183

Answers (2)

James Jithin
James Jithin

Reputation: 10555

When it ends with "/", would be referring find loading content from that directory. Suppose you have an extracted package in that folder. If you have a class com.abc.Test, to load it form a folder, you would need the file com/abc/Test.class in the folder you are referring to.

Upvotes: 1

Adel Boutros
Adel Boutros

Reputation: 10295

You have to iterate over the files in the directory and add them one by one

List<URL> urls = new ArrayList<>();
try(DirectoryStream<Path> directoryStream = Files.newDirectoryStream(Paths.get(BASE_DIRECTORY), "*.jar")) {
    for (Path path : directoryStream) {
        urls.add(path.toUri().toURL());
    }
}

URLClassLoader urlClassLoader = new URLClassLoader(urls.toArray(new URL[urls.size()]));

Upvotes: 2

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