Something like HashMap

[BigBear]

Hi all, I need some structure like HashMap, but it don't have to reorganize items. This is my code:

public static HashMap<Integer, String> lastTextbook() {
    HashMap<Integer, String> map = new HashMap<Integer, String>();

    map.put(-1, "New Headway");
    map.put(1, "Elementary");
    map.put(2, "Pre-intermediate");
    map.put(-2, "New English File");
    map.put(5, "Elementary");
    map.put(6, "Pre-intermediate");
    map.put(-3, "New Matrix");
    map.put(9, "Pre-intermediate");
    map.put(10, "Intermediate");

    return map;
}

and following code process it

Iterator it = lastTextbook().keySet().iterator();
while (it.hasNext()) {
    Integer value = (Integer)it.next();
    String text = (String)options.get(value);

    System.out.println(text);
}

This gives me following output

Elementary
Pre-intermediate
Elementary
Pre-intermediate
Pre-intermediate
Intermediate
New Matrix
New English File
New Headway

But I need exactly what I put. What Object I should use? Thank you :-)

[pbrockway2]

Consider using a Map but sorting the set of keys to obtain the ordering you want and then iterating over that.

(It might help to describe the output you want: "I need exactly what I put" is a bit ambiguous. What is supposed to happen if a value is associated with a key and then, much later, another value is associated with the same key?)

Another approach would be to have two collections: a map and an list of map entries. You would have to keep the two in sych.

[BigBear]

Hi, I'm sorry for ambiguous expression. With this "I need exactly what I put" I meant that:
I put items into set in this order

map.put(-1, "New Headway");
map.put(1, "Elementary");
map.put(2, "Pre-intermediate");
map.put(-2, "New English File");
map.put(5, "Elementary");
map.put(6, "Pre-intermediate");
map.put(-3, "New Matrix");
map.put(9, "Pre-intermediate");
map.put(10, "Intermediate");

so anytime I'll want to go through this map, I'll get back the same order (by keys). In this case I get back following:

New Headway
Elementary
Pre-intermediate
New English File
Elementary
Pre-intermediate
New Matrix
Pre-intermediate
Intermediate

Or if I'll change whichever value I'll get something like this:

StringAssociatedWithKey-1
StringAssociatedWithKey1
StringAssociatedWithKey2
StringAssociatedWithKey-2
StringAssociatedWithKey5
StringAssociatedWithKey6
StringAssociatedWithKey-3
StringAssociatedWithKey9
StringAssociatedWithKey10

Thank you

[JosAH]

Read the API for the LinkedHashMap class.

kind regards,

Jos

[BigBear]

Thank you very much :-)