问题代码：

java">public static void main(String[] args) throws Exception{Map<String,Object> map = new HashMap<>();map.put("a",1);List<Map<String,Object>> l1 = new ArrayList<>();l1.add(map);List<Map<String,Object>> l2 = new ArrayList<>();System.err.println("l1:" + new Gson().toJson(l1));System.err.println("l2:" + new Gson().toJson(l2));l2.addAll(l1);for (Map<String, Object> mapUtil : l2) {mapUtil.put("b",1);}System.err.println("l1:" + new Gson().toJson(l1));System.err.println("l2:" + new Gson().toJson(l2));}

打印：

java">l1:[{"a":1}]
l2:[]
l1:[{"a":1,"b":1}]
l2:[{"a":1,"b":1}]

可以看到我明显改的是l2，l1怎么也变了呢，原因就在 addAll()
修改代码：

java">public static void main(String[] args) throws Exception{Map<String,Object> map = new HashMap<>();map.put("a",1);List<Map<String,Object>> l1 = new ArrayList<>();l1.add(map);List<Map<String,Object>> l2 = new ArrayList<>();System.err.println("l1:" + new Gson().toJson(l1));System.err.println("l2:" + new Gson().toJson(l2));l2 =(List<Map<String,Object>>) SerializationUtils.clone((Serializable) l1);for (Map<String, Object> mapUtil : l2) {mapUtil.put("b",1);}System.err.println("l1:" + new Gson().toJson(l1));System.err.println("l2:" + new Gson().toJson(l2));}

打印：

java">l1:[{"a":1}]
l2:[]
l1:[{"a":1}]
l2:[{"a":1,"b":1}]

完美