想要将list列表转换成map对象。
```java
@GetMapping("/bar")
public Result bar(){
//查询出所有
List<Xinzitongji> list = xinzitongjiService.findAll();
return Result.success();
}
获取到的列表如下:
[Xinzitongji(id=1, xuehao=2021900123, xingming=李四, xinzi=2-3k, biyeshijian=null), Xinzitongji(id=2, xuehao=2021900124, xingming=王五, xinzi=2-3k, biyeshijian=null), Xinzitongji(id=3, xuehao=2021800123, xingming=张三, xinzi=2-3k, biyeshijian=null), Xinzitongji(id=4, xuehao=2021800124, xingming=小红, xinzi=3-4k, biyeshijian=null), Xinzitongji(id=5, xuehao=2021800112, xingming=小华, xinzi=2-3k, biyeshijian=null), Xinzitongji(id=6, xuehao=2021900556, xingming=李七, xinzi=2-3k, biyeshijian=null), Xinzitongji(id=8, xuehao=2022900588, xingming=许七, xinzi=3-4k, biyeshijian=null), Xinzitongji(id=9, xuehao=2022123456, xingming=迪迦, xinzi=2-3k, biyeshijian=null)]
数据库如下:
我想要得到一个如下map数据:统计出有多少个xinzi类别,然后统计各个类别的数量
想知道后端代码怎么写!