Character.isDigit() Character.isLowerCase() Character (Java Platform SE 7 ) documented Character (Java Platform SE 7 ) documentation of Character Character (Java Platform SE 7 ) char Character Character (Java Platform SE 7 ) java.lang.Character Unicode Character Representations Character (Java Platform SE 7 ) Character toUpperCase Character#isLetter Java Character Docs Code Units Character docs Character (Java Platform SE 7 ) toUpperCase way such characters would be stored in Java's String class Character Character Character.digit(input.charAt(i), 10) Character (Java Platform SE 7 ) Character java.lang.Character.MAX_RADIX java.lang.Character.MAX_RADIX Character.forDigit(digit, 16) Character (Java Platform SE 7 ) Character Character (Java Platform SE 7 ) Character Character.isLowerCase() documented Character (Java Platform SE 7 ) Character.isDigit() Character Character Character#isLetter this Character (Java Platform SE 7 ) Character (Java Platform SE 7 ) Character.isLetter() Character.isLowerCase() Character Character (Java Platform SE 7 ) Character#isWhitespace Character (Java Platform SE 7 ) Character (Java Platform SE 7 ) upper case Character (Java Platform SE 7 ) Character.isLetter() toUpperCase Character Character#isAlphabetic Character (Java Platform SE 7 ) Character#isLetter Character (Java Platform SE 7 ) Character#isLetter Character toUpperCase Character (Java Platform SE 7 ) Character#isWhitespace Character.isDigit() Character Character Character.isLetter(char) int Character lower case Character.isDigit(char) Character Character#isAlphabetic SIZE Character Java identifier-part characters