仅供参考，勿要模仿

时间：2014-03-03 17:09:38 收藏：0 阅读：494
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.regex.Matcher;
import 
java.util.regex.Pattern;
 
public 
class WordsCounter {
    public 
static void main(String[] args) throws 
Exception {
 
        BufferedReader reader = new 
BufferedReader(new 
FileReader(
                "main.txt"));
        StringBuffer buffer = new 
StringBuffer();
        String line = null;
        while 
((line = reader.readLine()) != null) {
            buffer.append(line);
        }
        reader.close();
        Pattern expression = Pattern.compile("[a-zA-Z]+");// 定义正则表达式匹配单词
        String string = buffer.toString();
        Matcher matcher = expression.matcher(string);//
        Map<String, Integer> map = new 
TreeMap<String, Integer>();
        String word = "";
        int 
times = 0;
        // 是否匹配单词
        while 
(matcher.find()) {
            // 得到一个单词-树映射的键
            word = matcher.group();
            // 如果包含该键，单词出现过
            if 
(map.containsKey(word)) {
                // 得到单词出现的次数
                times = map.get(word);
                map.put(word, times + 1);
            } else 
{
                // 否则单词第一次出现，添加到映射中
                map.put(word, 1);
            }
        }
         
        /*
         * 排序
         */
        List<Map.Entry<String, Integer>> list = new 
ArrayList<Map.Entry<String, Integer>>(
                map.entrySet());
        /*
         * 定义排序规则，按照Entry的Value排序
         */
        Comparator<Map.Entry<String, Integer>> comparator = new 
Comparator<Map.Entry<String, Integer>>() {
            public 
int compare(Map.Entry<String, Integer> left,
                    Map.Entry<String, Integer> right) {
                return 
(left.getValue()).compareTo(right.getValue());
            }
        };
        // 利用Collections类的sort方法来排序，按照自定义的规则排序
        Collections.sort(list, comparator);
        // 打印最多五个
        int 
last = list.size() - 1;
        for 
(int i = last; i > last - 5; i--) {
            String key = list.get(i).getKey();
            Integer value = list.get(i).getValue();
            System.out.println(key + " :" 
+ value);
        }
    }
}
仅供参考，勿要模仿,布布扣,bubuko.com
原文：http://www.cnblogs.com/hubaoyue/p/3577447.html