get string value from HashMap depending on key name

Question

I have a HashMap with various keys and values, how can I get one value out?

I have a key in the map called my_code, it should contain a string, how can I just get that without having to iterate through the map?

So far I've got..

   HashMap newMap = new HashMap(paramMap);
   String s = newMap.get("my_code").toString();

I'm expecting to see a String, such as "ABC" or "DEF" as that is what I put in there initially, but if I do a System.out.println() I get something like java.lang.string#F0454

Sorry, I'm not too familiar with maps as you can probably guess ;)

Answer 1

Just use Map#get(key) ?

Object value = map.get(myCode);

Here's a tutorial about maps, you may find it useful: http://java.sun.com/docs/books/tutorial/collections/interfaces/map.html.

Edit: you edited your question with the following:

I'm expecting to see a String, such as "ABC" or "DEF" as that is what I put in there initially, but if I do a System.out.println() I get something like java.lang.string#F0454

Sorry, I'm not too familiar with maps as you can probably guess ;)

You're seeing the outcome of Object#toString(). But the java.lang.String should already have one implemented, unless you created a custom implementation with a lowercase s in the name: java.lang.string. If it is actually a custom object, then you need to override Object#toString() to get a "human readable string" whenever you do a System.out.println() or toString() on the desired object. For example:

@Override
public String toString() {
    return "This is Object X with a property value " + value;
}

Answer 2

Your question isn't at all clear I'm afraid. A key doesn't have a "name"; it's not "called" anything as far as the map is concerned - it's just a key, and will be compared with other keys. If you have lots of different kinds of keys, I strongly suggest you put them in different maps for the sake of sanity.

If this doesn't help, please clarify the question - preferrably with some code to show what you mean.

Answer 3

map.get(myCode)

Answer 4

You can use the get(Object key) method from the HashMap. Be aware that i many cases your Key Class should override the equals method, to be a useful class for a Map key.

Answer 5

the question isn't a clear as it could be.

If you are only storeing keys/values as strings, then this will work...

HashMap<String, String> newMap = new HashMap<String, String>();
newMap.put("my_code", "shhh_secret");
String value = newMap.get("my_code");

The question is what gets populated in the paramap? (key & value)