get string value from HashMap depending on key name

Just use Map#get(key) ?

Object value = map.get(myCode);

Here's a tutorial about maps, you may find it useful: https://docs.oracle.com/javase/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;
}

If you are storing 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 HashMap (key & value)