1 package homework;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileReader;
 6 import java.io.IOException;
 7 import java.util.HashMap;
 8 import java.util.Iterator;
 9 import java.util.Map;
10 import java.util.Set;
11 import java.util.StringTokenizer;
12 import java.util.TreeSet;
13 
14 public class FileWordsCount {
15     public static void main(String[] args) {
16         
17         long time1 = System.currentTimeMillis();
18         
19         try {
20             BufferedReader br = new BufferedReader(new FileReader("D:\\wordtest.txt"));
21             String s;
22             StringBuffer sb = new StringBuffer();
23             while((s = br.readLine())!= null){
24                 sb.append(s);
25             }
26             Map<String,Integer> map = new HashMap<String,Integer>();
27             StringTokenizer st = new StringTokenizer(sb.toString(), ",.! ?\n");
28             while(st.hasMoreTokens()){
29                 String letter = st.nextToken();
30                 int count;
31                 if(map.get(letter) == null){
32                     count = 1;
33                 }else{
34                     count = map.get(letter).intValue()+1;
35                 }
36                 map.put(letter, count);
37             }
38             Set<WordEntity> set = new TreeSet<WordEntity>();
39             for(String key:map.keySet()){
40                 set.add(new WordEntity(key, map.get(key)));
41             }
42             /*System.out.print("单词        次数\n");
43             for(Iterator<WordEntity> it = set.iterator();it.hasNext();){
44                 WordEntity w = it.next();
45                 System.out.println(w.getKey()+"    ："+w.getCount());
46             }*/
47     
48             int count = 1;
49             for(Iterator<WordEntity> it = set.iterator();it.hasNext();){
50                 WordEntity w = it.next();
51                 System.out.println("Top"+count+": "+w.getKey()+"     次数："+w.getCount());
52                 if(count == 10){
53                     break;
54                 }
55                 count++;
56             }
57         } catch (FileNotFoundException e) {
58             System.out.println("文件未找到！");
59         } catch (IOException e){
60             System.out.println("文件读异常！");
61         }
62         long time2 = System.currentTimeMillis();
63         System.out.println("耗时：");
64         System.out.println(time2 - time1+"ms");
65     }
66 }

 1 package homework;
 2 
 3 public class WordEntity implements Comparable<WordEntity>{
 4     
 5     public WordEntity(String key,Integer count){
 6         this.key = key;
 7         this.count = count;
 8     }
 9 
10     public String getKey(){
11         return key;
12     }
13     
14     public Integer getCount(){
15         return count;
16     }
17     
18     @Override
19     //cmp升序。-cmp降序排列  TreeSet会调用WorkForMap的compareTo方法来决定自己的排序
20     public int compareTo(WordEntity o) {
21         int cmp = count.intValue() - o.count.intValue();
22         return (cmp == 0 ? key.compareTo(o.key):-cmp); 
23     }
24     
25     @Override
26     public String toString() {    
27         return key + "出现次数：" + count;
28     }
29     
30     private String key;
31     private Integer count;
32     
33 }

 1 package homework;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.FileReader;
 5 import java.util.ArrayList;
 6 import java.util.Collections;
 7 import java.util.Comparator;
 8 import java.util.List;
 9 import java.util.Map;
10 import java.util.TreeMap;
11 import java.util.regex.Matcher;
12 import java.util.regex.Pattern;
13 
14 public class WordCount {
15     public static void main(String[] args) throws Exception {
16         
17         long time1 = System.currentTimeMillis();
18 
19         BufferedReader reader = new BufferedReader(new FileReader(
20                 "D:\\wordtest.txt"));
21         StringBuffer buffer = new StringBuffer();
22         String line = null;
23         while ((line = reader.readLine()) != null) {
24             buffer.append(line);
25         }
26         reader.close();
27         Pattern expression = Pattern.compile("[a-zA-Z]+");// 定义正则表达式匹配单词
28         String string = buffer.toString();
29         Matcher matcher = expression.matcher(string);//
30         Map<String, Integer> map = new TreeMap<String, Integer>();
31         String word = "";
32         int times = 0;
33         while (matcher.find()) {// 是否匹配单词
34             word = matcher.group();// 得到一个单词-树映射的键
35             if (map.containsKey(word)) {// 如果包含该键，单词出现过
36                 times = map.get(word);// 得到单词出现的次数
37                 map.put(word, times + 1);
38             } else {
39                 map.put(word, 1);// 否则单词第一次出现，添加到映射中
40             }
41         }
42         /*
43          * 核心：如何按照TreeMap 的value排序而不是key排序.将Map.Entry放在集合里，重写比较器，在用
44          * Collections.sort(list, comparator);进行排序
45          */
46 
47         List<Map.Entry<String, Integer>> list = new ArrayList<Map.Entry<String, Integer>>(
48                 map.entrySet());
49         /*
50          * 重写比较器
51          * 取出单词个数（value）比较
52          */
53         Comparator<Map.Entry<String, Integer>> comparator = new Comparator<Map.Entry<String, Integer>>() {
54             public int compare(Map.Entry<String, Integer> left,
55                     Map.Entry<String, Integer> right) {
56                 return (left.getValue()).compareTo(right.getValue());
57             }
58         };
59         Collections.sort(list, comparator);// 排序
60         // 打印
61         int last = list.size() - 1;
62         for (int i = last; i > last-10; i--) {
63             String key = list.get(i).getKey();
64             Integer value = list.get(i).getValue();
65             System.out.print("Top"+i+"  : ");
66             System.out.println(key + " " + value);
67         }
68         long time2 = System.currentTimeMillis();
69         System.out.println("耗时：");
70         System.out.println(time2 - time1+"ms");
71     }
72 }