At the beginning, write String ss = new JSONArray.fromObject(list).toString();
I found that the error was reported. I used to type it according to the error. I was still depressed when the error was reported. Then I searched it online.
① Change the data under the database tool class to String type,
②Because the related jar package of JSONArray.fromObject is not imported
While searching, by the way, I asked the bosses who have been working in the group for many years,
As I was investigating, the group began to talk, and the two sentences were resolved.
The big guy told me that removing the new instantiated object is like this.
I just realized it. I got used to knocking and bringing new, and the consequences of removing it were correct. The boss also said that the basic skills of java are not solid, so I should really reflect on it.