How to get a HashMap value with three values

Question

If I have a HashMap with a such key: [pubDate, title, link] and such value(example):

[Thu, 03 Jan 2013 21:50:02 +0100, Transferts - YBX : ''Je change de dimension'', http://www.link.fr/info/link_informations.html] 

Can I retrieve the link http://www.link.fr/info/link_informations.html ? Code:

    for (int i = 0; i < nl.getLength(); i++) {                     // creating new HashMap                     map = new HashMap<String, String>();                     Element e = (Element) nl.item(i);                     // adding each child node to HashMap key => value                     map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));                     map.put(KEY_LINK, parser.getValue(e, KEY_LINK));                      map.put(KEY_DATE, parser.getValue(e, KEY_DATE));                     //map.put(KEY_DESC, parser.getValue(e, KEY_DESC));                      // adding HashList to ArrayList                     menuItems.add(map);  } 

Answer 1

I just faced the same issue and decided to map my key to an Entry. This allows for the same indexing features provided by a map while having more than one property associated with a key. I think it's a much neater solution that creating a separate class or nesting maps.

Map<String, Entry<Action, Boolean>> actionMap = new HashMap<String, Entry<Action, Boolean>>();  actionMap.put("action_name", new SimpleEntry(action, true)); 

To use the data later:

Entry<Action, Boolean> actionMapEntry = actionMap.get("action_name");  if(actionMapEntry.value()) actionMapEntry.key().applyAction(); 

My personal use of this was a map of named functions. Having selected the function by name, the function would be run and the boolean would determine whether or not cleanup was needed in processing.

Answer 2

You create an object that holds all three subkeys of the key as attributes. Make sure to implement equals and hashCode properly.

public class MyKey {   public MyKey(String subkey1, String subkey2, String subkey3) {     ...   } } 

Use such object as a key of your map:

Map<MyKey, String> myMap = ....; myMap.get(new MyKey("Thu", "03 Jan 2013 21:50:02 +0100", "Transferts - YBX")); 

Have fun!