[javaguru]

Maps do not provide an iterator() method as do Lists and Sets. A Set of either keys (keySet()) or key-value Map.Entry elements (entrySet()) can be obtained from the Map, and one can iterate over that.

The order of the elements obtained from a Map depends on the type of Map they came from.

TreeMap
The elements are ordered by key.
HashMap
The elements will be in an unpredictable, "chaotic", order.
LinkedHashMap
The elements will be ordered by entry order or last reference order, depending on the type of LinkedHashMap.

Example - Iterating over the "entry set"

This example utility method prints the key-value pairs in a map.

// utility method dumpMap
public static void dumpMap(Map mp) {
    Iterator it = mp.entrySet().iterator();
    while (it.hasNext()) {
        Map.Entry pairs = (Map.Entry)it.next();
        System.out.println(pairs.getKey() + " = " + pairs.getValue());
    }
}