第二次作业

 1 import java.util.ArrayList;
 2 import java.util.Collections;
 3 import java.util.Comparator;
 4 import java.util.HashMap;
 5 import java.util.List;
 6 import java.util.Map;
 7 import java.util.Scanner;
 8 import java.util.Map.Entry;
 9 
10 public class Count {
11     private static String str;
12     public  Count (String str){
13         Count.str=str;
14     }
15     public static void main(String[] args) {
16         System.out.print("请输入您要测试的字符串：");
17         Scanner in=new Scanner(System.in);
18         str = in.nextLine();
19         count(str);
20         
21     }
22     
23     public static void count(String str){
24         String[] items = str.split(" ");
25         Map<String, Integer> map = new HashMap<String, Integer>();
26         for (String s : items) {
27             if (map.containsKey(s))
28                 map.put(s, map.get(s) + 1);
29             else {
30                 map.put(s, 1);
31             }
32         }
33         List<Entry<String, Integer>> list = new ArrayList<Entry<String, Integer>>();
34         for (Entry<String, Integer> entry : map.entrySet()) {
35             list.add(entry);
36         }
37         Collections.sort(list, new EntryComparator());
38 
39         for (Entry<String, Integer> obj : list) {
40             System.out.println(obj.getKey() + "\t" + obj.getValue());
41         }
42     }
43 }
44 
45 class EntryComparator implements Comparator<Entry<String, Integer>> {
46     public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
47         return o1.getValue() > o2.getValue() ? 0 : 1;
48     }
49 } 

1 import org.junit.Test;
2 public class CountTest {
3     @Test
4     public void testCount() throws Exception {
5         String str="i love you ! and you ? ";
6         Count.count(str);
7     }
8 }

 1 import java.util.Scanner;
 2 
 3 public class Reverse{
 4 
 5     public static void main(String[] args) {
 6         Scanner input = new Scanner(System.in);
 7         System.out.print("请输入您要颠倒的字符串：");
 8         String str = input.nextLine();
 9         Reverse.reverse(str);
10     }
11     public static void reverse(String str){
12         String[] strArr = str.split("\\s+|[,]");
13         StringBuffer result = new StringBuffer();
14         for(int i = strArr.length -1;i >=0; i--){
15             result.append(strArr[i] + " ");
16         }
17 
18         result.setCharAt(str.length()-0, (char) 0);
19         System.out.println("颠倒后的结果为:  "+result.toString());
20 
21     }
22 }

 1 import org.junit.Test;
 2 
 3 public class ReverseTest {
 4     
 5     @Test
 6     public void test() throws Exception {
 7         String str="how are you";
 8          Reverse.reverse(str);
 9     }
10 
11 }