문자열이 숫자인지 확인하는 방법 String str = "123"; boolean isNumeric = str.matches("[+-]?\\d*(\\.\\d+)?"); System.out.println(isNumeric); -> true예제public class SimpleTesting { public static void main(String[] args) { String str = "123"; boolean isNumeric = str.matches("[+-]?\\d*(\\.\\d+)?"); System.out.println(isNumeric); -> true str = "121xy"; isNumeri..