Java反射导入

Question

Just a quick question regarding Java's reflection mechanism. My program should load the .class items from a .jar file.

I get a java.lang.NoClassDefFoundError for classes within the jar file, that are importing outer packages (to which I don't have access). Is there any chance of passing the exception without having to import the required packages.

Thanks.

Answer 1

I don't believe so - in order for reflection to load, you have to load the class using a class loader and then can, for example, instantiate objects and execute methods, so you will need the dependencies.

If you don't want to instantiate or execute, then a bytecode library would allow you to inspect the contents of the class file.

Answer 2

Others are correct, you cannot import code from dependencies of dependencies, directly.

That being said, a great way to prevent this problem is to use build technologies like Maven and Gradle. When you import dependencies with either of those techs, you automatically import dependencies of dependencies.