Java.util.TreeMap

Question

hi,
We have a list of key,value pairs of state codes and state names implemented using TreeMap. The list is sort based on the key value but in the display when getting the values some of them are out of order.
say the key, value pair - sorted on values (as desired to be seen in listbox)
NE,Nebraska
NV,Nevada
NH,New Hampshire
NJ,New Jersey
NM,New Mexico
NY,New York
NC,North Carolina
ND,North Dakota
but the TreeMap sorts on the key and while getting the values on the UI, it is
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Is there a way to get the treeMap sorted on the values ?

Answer 1

Don't use strings. Use an object that contains both the abbreviation and the full name of the state. Have the toString() method return the full name... never mind, like this:public class USState implements Comparable {
  private String code;
  private String name;
  public USState(String pCode, String pName) {
    code = pCode;
    name = pName;
  public String toString() {
    return name;
  public String getStateCode() {
    return code;
  public int compareTo(Object other) {
    that = (USState) other;
    return this.name.compareTo(that.name);
  public boolean equals(Object other) {
    that = (USState) other;
    return this.name.equals(that.name);
  public int hashCode() {
    return name.hashCode();
}Then you can use "NC" as the key in your Map and new USState("NC", "North Carolina") as the value. It doesn't need to be a TreeMap because you don't need the list sorted by state code. You can sort the values set of your Map and you'll have the states in alphabetic order by name along with their abbreviations.