Java Set equality ignore case

Question

I want to check if all elements of two sets of String are equal by ignoring the letter\'s cases.

Set set1 ;
Set set2 ;
.
.
.
if(s         


        

Answer 1

Unfortunately, Java does not let you supply an external "equality comparer": when you use strings, HashSet uses only built-in hashCode and equals.

You can work around this problem by populating an auxiliary HashSet with strings converted to a specific (i.e. upper or lower) case, and then checking the equality on it, like this:

boolean eq = set1.size() == set2.size();
if (eq) {
    Set aux = new HashSet();
    for (String s : set1) {
        aux.add(s.toUpperCase());
    }
    for (String s : set2) {
        if (!aux.contains(s.toUpperCase())) {
            eq = false;
            break;
        }
    }
}
if (eq) {
    // The sets are equal ignoring the case
}