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
     
       map = new TreeMap
      
       ();		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
       
        
         > list = new ArrayList
         
          
           >( map.entrySet()); /* * 定义排序规则，按照Entry的Value排序 */ Comparator
           
            
             > comparator = new Comparator
             
              
               >() { public int compare(Map.Entry
               
                 left, Map.Entry
                
                  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); } }}