map 比较(两个map的key，value 是否一样)

1. 用equals 比较

public static void main(String[] args) {List<Map<String,Object>> list = new ArrayList<>();Map<String,Object> map1= new HashMap<>();map1.put("name","郭");map1.put("objId","1");list.add(map1);Map<String,Object> map2= new HashMap<>();map2.put("name","郭2");map2.put("objId","2");list.add(map2);//Map<String,Object> map3= new HashMap<>();map3.put("name","郭2");map3.put("objId","2");Map<String,Object> map4= new HashMap<>();map4.put("name","郭3");map4.put("objId","2");// trueif(list.contains(map3)){System.out.println("hhh");}// falseif(list.contains(map4)){System.out.println("hhh");}// true(可以用来比较两个map 的key ，value 是否一样)System.out.println(map2.equals(map3));}

底层逻辑：

 public boolean equals(Object o) {if (o == this)return true;if (!(o instanceof Map))return false;Map<?,?> m = (Map<?,?>) o;if (m.size() != size())return false;try {for (Entry<K, V> e : entrySet()) {K key = e.getKey();V value = e.getValue();if (value == null) {if (!(m.get(key) == null && m.containsKey(key)))return false;} else {if (!value.equals(m.get(key)))return false;}}} catch (ClassCastException unused) {return false;} catch (NullPointerException unused) {return false;}return true;}