On the java programming of Lock key users

topic description

A building has many doors, each door has a lock, each lock can be opened by multiple keys, each user has multiple keys, each key can open multiple locks, ensure that each key can open at least one lock, each lock can be opened by at least one key, write some ways.
1 add a new user
2 add a lock, corresponding to add a key
there are three classes: keys,locks,users. What are written in each of these three classes? What is the idea of this question?

sources of topics and their own ideas

teacher"s question

related codes

/ / Please paste the code text below (do not replace the code with pictures)

what result do you expect? What is the error message actually seen?

I look forward to seeing the idea of the topic, java rookie, but I really don"t know how to start.

Jun.04,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b33d68-2ac0e.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b33d68-2ac0e.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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