JDK Map接口很难作为迭代在EntrySetKeySet对象上迭代。 MapIterator提供了对Map的简单迭代。
public class MapIteratorTester {
    public static void main(String[] args) {
        IterableMap<String,String> map = new HashedMap<String, String>();
        map.put("1", "One");
        map.put("2", "Two");
        map.put("3", "Three");
        map.put("4", "Four");
        map.put("5", "Five");

        MapIterator<String,String> iterator = map.mapIterator();
        while (iterator.hasNext()){
            Object key = iterator.next();
            Object value =iterator.getValue();

            System.out.println("key:"+key);
            System.out.println("value:"+value);

            iterator.setValue(value+"_");
        }
        System.out.println(map);
    }
}

结果:

key:3
value:Three
key:5
value:Five
key:2
value:Two
key:4
value:Four
key:1
value:One
{3=Three_, 5=Five_, 2=Two_, 4=Four_, 1=One_}