week 9 jihoon - GANGNAM-JAVA/JAVA-STUDY GitHub Wiki Delete multiple items java optional์ ๋ํ ๊ธฐ๋ฅ ์ค๋ช ๊ณผ ์์๋ฅผ ์ค๋ช ํด๋ณด์์ค ์๋ฐ ๋๋ค & ํด๋ก์ ๋ ๋ฌด์์ธ๊ฐ?