1. Capitalize the first letter
// capitalize first letter public static String toUpperCaseFirstOne(String s) { if (Character.isUpperCase(s.charAt(0))) { return s; } else { return (new StringBuilder()).append(Character.toUpperCase(s.charAt(0))).append(s.substring(1)).toString(); } } // capitalize first letter public static String upperCaseFirstOne1(String str) { return str.substring(0, 1).toUpperCase() + str.substring(1); } // capitalize first letter public static String upperCaseFirstOne2(String str) { char[] ch = str.toCharArray(); if (ch[0] >= 'a' && ch[0] <= 'z') { ch[0] = (char) (ch[0] - 32); } return new String(ch); }
2. The first letter is lowercase
// Convert the first letter to lowercase public static String toLowerCaseFirstOne(String s) { if (Character.isLowerCase(s.charAt(0))) { return s; } else { return (new StringBuilder()).append(Character.toLowerCase(s.charAt(0))).append(s.substring(1)).toString(); } }