Character 新发现

BufferedReader f =
new BufferedReader(new FileReader("lettersAndDigits.txt" ));
int c = f.read(); // get the first char
StringBuffer letters = new StringBuffer();
StringBuffer digits = new StringBuffer();
// read the letters
while ( Character.isLetter((char)c) ) {//是否为单词
letters.append((char)c);
c = f.read();
}
// read the digits
while ( Character.isDigit((char)c) ) {//是否为数字
digits.append((char)c);
c = f.read();
}