22.2-按照升序显示不重复的单词

编写一个程序--从文本文件当中读取单词，并将所有不重复的单词按照升序显示，文本文件被作为命令行参数传递。

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Set;
import java.util.TreeSet;

public class exercise22_2 {
	public static void main(String args[]) throws IOException  {
		String fileName = args[0];
		Set<String> treeSet = new exercise22_2().getWordDiffereceByAsec(fileName);
		System.out.println(treeSet);
	}
    
	/**
	 * 如果采用read那样显示的话，第一个字母是不会显示的
	 * @param fileName
	 * @return
	 * @throws IOException
	 */
	private Set<String> getWordDiffereceByAsec(String fileName)
			throws IOException {
		BufferedReader buffer = new BufferedReader(new InputStreamReader(new FileInputStream(fileName)));
		Set<String> wordSet = new TreeSet<String>();
//		while(buffer.read() != -1){
//			String word = buffer.readLine();
//			wordSet.add(word);
//		}
		String word;
		while((word = buffer.readLine())!= null){
			wordSet.add(word);
		}
		return wordSet;
	}
}