java程序中如何添加按照字母顺序排序

public class Main2 {
public static void main(String[] args) {
int count = 0;
File file = new File("F:\1.txt");
String s = "";
StringBuffer buffer = new StringBuffer();
try {
BufferedReader br = new BufferedReader(new FileReader(file));
        try {
            while ((s = br.readLine()) != null) {
                buffer.append(s + '\n');
            }
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }   
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    Pattern p = Pattern.compile("\\b[a-zA-Z]+\\b");
    Matcher m = p.matcher(buffer.toString());
    while(m.find()) {
        System.out.println(m.group());
        count ++ ;
    }
    System.out.println("总共：" + count + "个单词");
}
}