1. Key keyword static, valatile, transient, synchronized, final, instanceof
2. collection system Collection, MAP
3. Concurrent: multithreading, ConcurrentHashMap
4. BIO, NIO system
The common sorting algorithms: bubble, select, insert, fast, merge, heap, hill, base
6. common encryption algorithm *** (understand just fine)
7. blocking queue system blockingQueue
8. The common design patterns and UML
9. The logging framework, WEBSOCKET, calendar time frame based calendar, java.time package (Learn like)
10 JVM system (understanding like)
11.mysql statement, basic data structures (familiar)
12. SSM frame (important)