hashmap的三种遍历方式_hashmap遍历

 
    /**
     * map集合的遍历方式
     */
    public static void main(String[] args) {
        HashMap<String, String> map = new HashMap<>();
        map.put("1","q");
        map.put("8","q2");
        map.put("2","q");
        map.put("3","q");
        map.put("8","q1");
        map.put("4","q");
        map.put("5","q");
        map.put("8","q3");
 
        //遍历一：获取map集合中的每一对键值对，分别获取key和value
        Set<Map.Entry<String, String>> entries = map.entrySet();
        for (Map.Entry<String, String> entry : entries) {
            System.out.println("key:" + entry.getKey() + " , value:" + entry.getValue());
        }
        System.out.println("====================================");
        //遍历二：获取所有的key，遍历key，获取出value
        Set<String> keySet = map.keySet();
        for (String key : keySet) {
            System.out.println("key:" + key + " , value:" + map.get(key));
        }
        System.out.println("====================================");
        //遍历三；迭代器的方式
        Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();
        while(iterator.hasNext()){
            Map.Entry<String, String> next = iterator.next();
            System.out.println("key:" + next.getKey() + " , value:" + next.getValue());
        }
    }