They're not just asking how do you use the HashMap class from the Java Collections API ... The toString method, I think, just represents that as a funky little JSON string or something like that. So ...

the JSON Binding API for Java. After a quick overview and installation instruction, I’ll show you how to use JSON-B to serialize and deserialize Java objects, arrays, and collections ...

In turn, this can be problematic when a developer generates XML or JSON that ... key in a map in Java’ problem are: Stick with the standard APIs and add a collection class like a ‘Vector’ or ...