ebt ebt - 21 days ago 7
Java Question

Java: how to convert a List<?> to a Map<String,?>

I would like to find a way to take the object specific routine below and abstract it into a method that you can pass a class, list, and fieldname to get back a Map.
If I could get a general pointer on the pattern used or , etc that could get me started in the right direction.

Map<String,Role> mapped_roles = new HashMap<String,Role>();
List<Role> p_roles = (List<Role>) c.list();
for (Role el : p_roles) {
mapped_roles.put(el.getName(), el);
}


to this? (Pseudo code)

Map<String,?> MapMe(Class clz, Collection list, String methodName)
Map<String,?> map = new HashMap<String,?>();
for (clz el : list) {
map.put(el.methodName(), el);
}


is it possible?

Answer

Here's what I would do. I am not entirely sure if I am handling generics right, but oh well:

public <T> Map<String, T> mapMe(Collection<T> list) {
   Map<String, T> map = new HashMap<String, T>();
   for (T el : list) {
       map.put(el.toString(), el);
   }   
   return map;
}

Just pass a Collection to it, and have your classes implement toString() to return the name. Polymorphism will take care of it.

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