java中switch的用法

 1 package codeAnal;
 2 
 3 public class SwitchDemo {
 4 
 5     public static void main(String[] args) {
 6         stringTest();
 7         breakTest();
 8         defautTest();
 9     }
10 
11     /*
12      * default不是必须的，也可以不写
13      * 输出：case two
14      */
15     private static void defautTest() {
16         char ch = ‘A‘;
17         switch (ch) {
18         case ‘B‘:
19             System.out.println("case one");
20             break;
21         case ‘A‘:
22             System.out.println("case two");
23             break;
24         case ‘C‘:
25             System.out.println("case three");
26             break;
27         }
28     }
29 
30     /*
31      * case语句中少写了break，编译不会报错
32      *     但是会一直执行之后所有case条件下的语句，并不再进行判断，直到default语句
33      *     下面的代码输出： case two
34      *                   case three
35      */
36     private static void breakTest() {
37         char ch = ‘A‘;
38         switch (ch) {
39         case ‘B‘:
40             System.out.println("case one");
41             
42         case ‘A‘:
43             System.out.println("case two");
44             
45         case ‘C‘:
46             System.out.println("case three");
47         default:
48             break;
49         }
50     }
51 
52     /*
53      * switch用于判断String类型
54      *     输出：It‘s OK!
55      */
56     private static void stringTest() {
57         String string = new String("hello");
58         switch (string) {
59         case "hello":
60             System.out.println("It‘s OK!");
61             break;
62 
63         default:
64             System.out.println("ERROR!");
65             break;
66         }
67     }
68 }