遍历Java Map

//1, get both key and value
        for(Entry<Integer, String> entry : map.entrySet())
        {
            Integer key = entry.getKey();
            String value = entry.getValue();
        }
        
        //2, get key or value
        for(Integer key : map.keySet())
        {
            Integer k = key;
        }
        
        for(String value : map.values())
        {
            String v = value;
        }
        
        
        //3, use Iterator, !!! recommend: iterator.remove()
        Iterator<Entry<Integer, String>> itr = map.entrySet().iterator();
        while(itr.hasNext())
        {
            Map.Entry<Integer, String> entry = itr.next();
            Integer key = entry.getKey();
            String value = entry.getValue();
        }