集合如何在java中制作嵌套HashMap

Question

我正在尝试将匿名hashmap放入另一个hashmap：-

Map<String, Object> requestBody=new HashMap<String, Object>();
requestBody.put("UPSSecurity", new HashMap<String, Object>().put("username","rohan"));
System.out.println(requestBody);

输出为：-

{UPSSecurity=null}

Answer 1

你也可以这样做

Map<String, Object> requestBody=new HashMap<String, Object>();
requestBody.put("UPSSecurity", new HashMap<String, Object>());
requestBody.get("UPSSecurity").put("username","rohan");

Answer 2

请使用此方法定义嵌套哈希映射

Map<String, Object> requestBody=new HashMap<String, Object>();
Map<String,Object> userdetails=new HashMap<String, Object>();
userdetails.put("username","rohan");
requestBody.put("UPSSecurity",userdetails );
System.out.println(requestBody);

输出：

{UPSSecurity={username=rohan}}