indexOf public class Main { public static void main(String[] args) { // indexOf String a = "hello Java"; System.out.println(a.indexOf("Java")); // 문자열 순서 숫자(0 부터) } } contains public class Main { public static void main(String[] args) { // contains String a = "Hello Java"; System.out.println(a.contains("Java")); } } charAt public class Main { public static void main(String[] args) { // charAt St..