How to sort a treemap based on its values?

Question

How can I sort a treemap using its values rather than the key?

Answer 1

You could try giving a Comparator that compare values instead of keys when you create the TreeMap.

    final TreeMap tree = new TreeMap();
    tree.put(1, "1");
    tree.put(2, "2");
    tree.put(3, "3");
    tree.put(4, "4");

    final TreeMap treeSortedByValues = new TreeMap(new Comparator()
    {
        public int compare(Integer o1, Integer o2)
        {
            return tree.get(o1).compareTo(tree.get(o2));
        }
    });
    treeSortedByValues.putAll(tree);

    for ( Entry e : treeSortedByValues.entrySet() )
    {
        System.out.println(e.getKey() + ": " + e.getValue());
    }