List containsKey 和Map contains 判断集合中是否包含某个值

map集合

//1.第一种
HashMap map = new HashMap();
        map.put("1", "value1");
        map.put("2", "value2");
        Iterator keys = map.keySet().iterator();
       while(keys.hasNext()){
            String key = (String)keys.next();
            if("2".equals(key)){
                System.out.println("存在key");
            }
        }

//2.第二种
boolean flag=map.containsKey("email")  

List集合

List list=new ArrayList();
list.add("224");
list.add("2252");
list.add("226");
list.add("227");
if(list.contains("2252")){
    System.out.print("包含");
}