https://sujl95.tistory.com/63
https://wisdom-and-record.tistory.com/48
https://blog.naver.com/hsm622/222212364489
https://catch-me-java.tistory.com/47
https://parkadd.tistory.com/48
https://www.notion.so/Thread-5fdb5d603a6a473186bf2738f482cedc
https://leemoono.tistory.com/26
https://www.notion.so/ac23f351403741959ec248b00ea6870e
https://yadon079.github.io/2021/java%20study%20halle/week-10
https://gblee1987.tistory.com/203
https://github.com/ChoiGiSung/JavaStudy/blob/main/10%EC%A3%BC%EC%B0%A8.md
https://www.notion.so/4589fc8a98ce4762ae78be5c2fe6cd1e