How to do a arraylist of hashtables in java?

Question

I would like to know if is it possible to create a vector of hashtables ?

i tried

java.util.Hashtable<String, String>[] info = new java.util.Hashtable<String, String>();

but haven't any luck :(

Thanks.

Answer 1

I think you want

ArrayList<Hashtable<String, String>> info = new ArrayList<Hashtable<String, String>>();

Answer 2

A Vector is a List, and a Hashtable is a Map, so what you want is a List of Maps.

I'd advise you to use ArrayList instead of Vector and HashMap instead of Hashtable, respectively (as discussed here and in many other questions), but most of all I'd advise you to change your requirements.

In most cases, you'd want a Map of Lists rather than a List of Maps, and if you do, I'd use one of the many custom implementations available, first and foremost Guava's Multimap.

Answer 3

You probably want:

ArrayList<Hashtable<String, String>> info =
    new ArrayList<Hashtable<String, String>>();

This can be simplified somewhat with type inference and a library such as Guava:

ArrayList<Hashtable<String, String>> info = Lists.newArrayList();

Answer 4

Try to make sure you are using as abstract an interface for the collections you are using as possible.

List<Map<String, String>> info= new ArrayList<Map<String, String>>();

Then you can add your hashtables

Map<String, String> infoElement= null;
for( something in someOtherThing ) {
    infoElement= new Hashtable<String, String>();
    // add your logic
    info.add(infoElement);
}