Java练习题_Map 统计一段文章中每个（或指定）单词出现的次数，

 1 import java.util.Collection;
 2 import java.util.HashMap;
 3 import java.util.Map;
 4 import java.util.Map.Entry;
 5 
 6 public class TestDay19_2 {
 7 
 8     public static void main(String[] args) {
 9 
10         String s = "As a student, we have study for many years. " + "During there years, we study Chinese, English, "
11                 + "science and so on. In this period, with the improvement of our knowledge,"
12                 + "we not only read the books in class but also read extracurricular after school. "
13                 + "In my opinion Dream of the red chamber is the best book I have read. "
14                 + "In this book, the great author Cao xueqin his view about love. "
15                 + "He had firmly faith in what is the true love and try to tell us "
16                 + "that there are different kinds of love, "
17                 + "only one kind which should be considered as True Love. In a dream, "
18                 + "and under mythical circumstances, the main character of the novel, "
19                 + "Jia baoyu, met the Fairy Disenchantment in the Land of Illusions. "
20                 + "She showed him three registers each containing the names "
21                 + "and the happenings in life of 12 girls in his clan. "
22                 + "Each girl represents a kind of love. From the stories " + "which are unfolding in the novel, "
23                 + "the reader should know the characteristics of the different kinds of love, "
24                 + "and should be able to distinguish True Love from the other kinds. "
25                 + "True love is acceptance, committal, mutual and without any post conditions. "
26                 + "The love between Lin daiyu and Jia baoyu is considered to be True Love. "
27                 + "Just saying or hearing I love you is not good enough because talk is cheap. "
28                 + "Action in mutual commitment is essential, as we can see in the novel. "
29                 + "We always have dreams. What‘s ours dream? Do you know what you exactly want? "
30                 + "And do you work hard for it. In this book, "
31                 + "you can taste the feeling of the author about his strong will. In his words, "
32                 + "you can find the charm of Chinese. It is not a book, but a precious deposits. "
33                 + "You can get a lot from it. But unfortunately, "
34                 + "the novel was never completed to such a state. On the other hand, maybe, "
35                 + "it is another kind of beauty of the book. If you have not read this book yet, "
36                 + "just go and read it. You will love it. ";
37         String[] ss = s.split(" ");
38 
39         HashMap<String, Integer> hm = new HashMap<>();
40         // 指定想要统计的单词
41         hm.put("this", 0);
42         hm.put("is", 0);
43         hm.put("a", 0);
44         hm.put("book", 0);
45         hm.put("an", 0);
46 
47         for (int i = 0; i < ss.length; i++) {
48             String word = ss[i];
49             if (hm.containsKey(word)) {
50                 hm.put(word, hm.get(word) + 1);
51             }
52             // 把下面这三行放开就是统计每个单词的次数
53             // else{
54             // hm.put(ss[i], 1);
55             // }
56         }
57 
58         Collection<Map.Entry<String, Integer>> c = hm.entrySet();
59         for (Entry<String, Integer> entry : c) {
60             System.out.println(entry.getKey() + "出现了" + entry.getValue() + "次");
61         }
62     }
63 }