https://www.w3schools.com/java/ref_string_join.asp Java String join() MethodW3Schools offers free online tutorials, references and exercises in all the major languages of the web. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more.www.w3schools.com cf) https://imswengineer.tistory.com/776 [JAVA] StringUtils.join()https://blog.naver.com/seek316/2223498126..