TreeMap<Integer, String> returns an single value in java
<pre><code>TreeMap&lt;Integer, String&gt; map = new TreeMap&lt;Integer, String&gt;();

    map.put(1, "example");
    map.put(1, "example2");
    map.put(1, "example3");

    Iterator&lt;Integer&gt; itr = map.keySet().iterator();

    while (itr.hasNext()) {
        Object obj = itr.next();
        System.out.println(map.get(obj));

    }
</code></pre>

<p>It always returns <code>"example3"</code>.  May I know why?  Why can I not retrieve all the values?
How are the keys in <code>Treemap</code> ordered?  The keys should be from 0,1,2...</p>
