Demonstrate a case-insensitive map using Treemap and a comparator.

CaseInsensitiveMap.java

import java.util.TreeMap;

public class CaseInsensitiveMap {
    public static void main(String[] args) {
        TreeMap<String, String> map = new TreeMap<String, String>(
                String.CASE_INSENSITIVE_ORDER);
        assert map.isEmpty();

        map.put("a", "b");
        assert map.size() == 1;
        assert map.get("a").equals("b");
        assert map.get("A").equals("b");

        map.put("A", "c");
        assert map.size() == 1;
        assert map.get("a").equals("c");
        assert map.get("A").equals("c");

        map.put("b", "b");
        assert map.size() == 2;
    }
}