Ignore case while comparing string with keyvalue in the hashmap

Question

I am trying to check if my hashmap key set contains the string 'buffSB.toString()'. But I wanted to compare ignoring case (upper or lower).

static StringBuilder buffSB = new StringBuilder(); 

buffSB.append(alphabet);

Map<String, String> pref =  new Datamatch().main();  // Getting the Hashmap from other class

if(pref.containsKey(buffSB.toString()))             //This is where I need to ignore case while searching string in the map key set 
  { 
      String val = pref.get(buffSB.toString());
  }

Any help will be greatly appreciated!!!

Answer 1

If you see the implementation of HashMap getKey method you have to pass the proper key to generate the hash value and get the actual value from that bucket.

    if (key == null)
        return getForNullKey();
    int hash = hash(key.hashCode());
    for (Entry<K,V> e = table[indexFor(hash, table.length)];
         e != null;
         e = e.next) {
        Object k;
        if (e.hash == hash && ((k = e.key) == key || key.equals(k)))
            return e.value;
    }
    return null;

Three solutions

    Map<String, String> pref = new TreeMap<String, String>(String.CASE_INSENSITIVE_ORDER);

OR

    Map<String, String> map = new CaseInsensitiveMap<String, String>();

OR

    Looping through map with the ignore case