split() : 문자열 -> 배열, join() : 배열 -> 문자열

split()

split() : 문자열을 특정 구분자로 나눠서 배열로 만들어 준다

String phone = "010-1234-5678";
String[] phoneArray = phone.split("-");
System.out.println("phoneArray  >> " + phoneArray[0]); // 출력 : phoneArray >> 010
System.out.println("phoneArray  >> " + phoneArray[1]); // 출력 : phoneArray >> 1234
System.out.println("phoneArray  >> " + phoneArray[2]); // 출력 : phoneArray >> 5678
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//하나의 값만 가져오기
String phone = "010-1234-5678";
String arrStrPhone = phone.split("-")[0];
System.out.println("arrStrPhone >> " + arrStrPhone); // 출력 : arrStrPhone >> 010
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//limit 만큼 문자열 나누기
String phone = "010-1234-5678";
String[] arrLimitPhone = phone.split("-",2);
System.out.println("arrLimitPhone >> " + phoneArray[0]); // 출력 : arrLimitPhone >> 010
System.out.println("arrLimitPhone >> " + phoneArray[1]); // 출력 : arrLimitPhone >> 1234-5678

 

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join()

join() : 배열을 문자열로 합쳐준다

// 문자
String red = "빨강";
String blue = "파랑";
System.out.println( "redAndBlue >> " +  String.join(",", red, blue)); // 출력 : redAndBlue >> 빨강,파랑
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// 배열
String[] color = ["빨강","노랑","초록"];
System.out.println( "colorJoin >> " + String.join("+", color) ); // 출력 : colorJoin >> 빨강+노랑+초록
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// List
List<String> color = new ArrayList<>();
color.add("빨강");
color.add("파랑");
color.add("초록");
System.out.println( "arrColor >> " + String.join("-",color) ); // 출력 : arrColor >> 빨강-파랑-초록