// String 기능 활용 예시
String str = "ABCD";
// (1) length
int strLength = str.length();
System.out.println(strLength);
// (2) charAt(int index)
char strChar = str.charAt(1);
System.out.println(strChar);
// (3) substring(int fromIdx, int toIdx)
String strSub = str.substring(0, 3);
System.out.println(strSub);
// (4) equals(String str)
String newStr = "ABCD";
boolean strEqual = newStr.equals(str);
System.out.println(strEqual);
// (5) toCharArray() : String -> char[]
char[] strCharArray = str.toCharArray();
// (6) 반대로 char[] -> String -> char
char[] charArray = {'A', 'B', 'C'};
String charArrayString = new String(charArray);
System.out.println(charArrayString);