JAVA萌新求教，迭代器的使用问题

Question

```public class MapDeemo {

public static void main(String[] args) {
    String[] arr = "this is a cat and that is a mice".split(" ");
    Map<String,Integer> m = new HashMap<String,Integer>();
    for(String key:arr){//遍历数组
        //System.out.println(key);
        if(!m.containsKey(key)){
            m.put(key, 1);
        }
        else{
            m.put(key, m.get(key)+1);
            }

    }
    Set<String> keySet = m.keySet();
    Iterator<String> iter = keySet.iterator();
    while(iter.hasNext()){
        /*Integer value = m.get(iter.next());
        System.out.println(iter.next()+"-->"+value);
        */
        String key = iter.next();
        Integer value = m.get(key);
        System.out.println(key+"-->"+value);

    }

}

}

在使用迭代器遍历的时候，
/*Integer value = m.get(iter.next());
            System.out.println(iter.next()+"-->"+value);
            */
            String key = iter.next();
            Integer value = m.get(key);
            System.out.println(key+"-->"+value);
            这里被注释过的代码和下面的代码仿佛没什么区别啊，为什么我在第一次编写时，使用了注释了的代码，结果却是不正确的呢。。求大佬告知

Answer 1

/*Integer value = m.get(iter.next());
System.out.println(iter.next()+"-->"+value);
*/
执行了iter.next() 两次，当然不对~