Using class from another groovy file as a type in a Jenkins pipeline script - jenkins

Question

I'm a groovy novice, so not sure if this is possible. I need something like an import, but not quite. Here is the simplified code example of what I'm trying to do:
in file FileToProcess.groovy I have
class FileToProcess implements Serializable {
String FileName
FileToProcess(fileName) {
this.FileName = fileName;
}
}
and then in a JenkinsFile I want to do something like
F1 = new FileToProcess('A');
List<FileToProcess> allFiles = new ArrayList<FileToProcess>();
allFiles.add(F1);
​for (FileToProcess file : allFiles) {
System.out.println(file.FileName);
}
Now, on StackOverflow I've found examples of how to instantiate a class from another file, for example here or here, and that solves the line
F1 = new FileToProcess('A');
but it does not show how to use that class as a type in a declaration, for example
List<FileToProcess> allFiles = new ArrayList<FileToProcess>();
gives me "unable to resolve class FileToProcess". I also know that using a class as a type like this should work, because it does when I put the class in the same JenkinsFile, so the problem seems to be just that the class is not visible in the JenkinsFile.
Is there a way to do this?

Answer 1

I'm not sure how you tried to setup your class libraries but I attempted the same while using a class from a pipeline shared library and it worked as intended
https://jenkins.io/doc/book/pipeline/shared-libraries/
I did do it a little differently:
assuming you places the file under src/org/Foo.groovy
import org.Foo
def list = new ArrayList<Foo>
list.add(new Foo('str1'))
list.add(new Foo('str2'))