Unique Word Abbreviation

An abbreviation of a word follows the form . Below are some examples of word abbreviations:

a) it                      --> it    (no abbreviation)

     1
b) d|o|g                   --> d1g

              1    1  1
     1---5----0----5--8
c) i|nternationalizatio|n  --> i18n

              1
     1---5----0
d) l|ocalizatio|n          --> l10n

Assume you have a dictionary and given a word, find whether its abbreviation is unique in the dictionary. A word's abbreviation is unique if no other word from the dictionary has the same abbreviation.

Example:

Given dictionary = [ "deer", "door", "cake", "card" ]

isUnique("dear") -> false; 
isUnique("cart") -> true
isUnique("cane") -> false
isUnique("make") -> true

Tips:

1. 注意全局变量map，以及在哪里new map;
2. 需要注意，字典里可能有重复选项，也可能这个词在字典里没有，所以

if (map.containsKey(abb)) {
    if (!map.get(abb).equals(str)) {
        map.put(abb,"");
    }
}

还有一段：
return !map.containsKey(getAbb(word))||map.get(getAbb(word)).equals(word)

另外需要注意toString方法；

代码：

 public class ValidWordAbbr {
    HashMap<String, String> map;
    public ValidWordAbbr(String[] dictionary) {
        map = new HashMap<String, String>();
        for (String str : dictionary) {
            String abb = getAbb(str);
            if (map.containsKey(abb)) {
                if (!map.get(abb).equals(str)) {
                    map.put(abb,"");
                }
            } else {
                map.put(abb, str);
            }
        }
    }

    public boolean isUnique(String word) {
        return !map.containsKey(getAbb(word))||map.get(getAbb(word)).equals(word);
    }

    private String getAbb(String word) {
        if (word.length() <= 2) {
            return word;
        }
        String abb = word.charAt(0) + Integer.toString(word.length() - 2) + word.charAt(word.length() - 1);
        return abb;
    }
}

// Your ValidWordAbbr object will be instantiated and called as such:
// ValidWordAbbr vwa = new ValidWordAbbr(dictionary);
// vwa.isUnique("Word");
// vwa.isUnique("anotherWord");