Displaying a HashSet in alphabetical order

Question

I neded to display a HashSet in alphabetical order,but only display those words beginning with 'a','h','m' - both lower and upper case. Can someone give me a clue?

Answer 1

Not the most efficient, but simple...import java.util.*;
public class Test {
    public static void main(String[] args) {
     String[] data = {
               "Tango","Uniform","Victor","Whiskey","Xray","Yankee",
               "November","Oscar","Papa","Quebec","Romeo","Sierra",
               "Mike","Zulu",
               "Alpha","Bravo","Charlie","Delta","Echo","Foxtrot",
               "Golf","Hotel","India","Juliet","Kilo","Lima"
     char[] letters = {'a','h','m'};
     HashSet hs = new HashSet();
     // initialize hashset
     for (int i=0; i<data.length; i++) hs.add(data);
     // extract to array
     Object[] hsArray = hs.toArray();
     // sort array
     Arrays.sort(hsArray);
     // print matching items
     for (int i=0; i<hsArray.length; i++) {
     char c = Character.toLowerCase(((String)hsArray[i]).charAt(0));
     for (int j=0; j<letters.length; j++) {
          if (letters[j]==c) {
          System.out.println(hsArray[i]);
          break;