How to check for key in a Map irrespective of the case? [duplicate]

Answer 1

You can use a TreeMap with a custom, case-insensitive Comparator (that uses String.compareToIgnoreCase())

For example:

Map map = 
    new TreeMap(CaseInsensitiveComparator.INSTANCE);

class CaseInsensitiveComparator implements Comparator {
    public static final CaseInsensitiveComparator INSTANCE = 
           new CaseInsensitiveComparator();

    public int compare(String first, String second) {
         // some null checks
         return first.compareToIgnoreCase(second);
    }
}

Update: it seems that String has already defined this Comparator as a constant.