流程结构注意点

1         switch(str) {//打印出3
2             case "春天" : System.out.println(1);break;
3             case "夏天" : System.out.println(2);break;
4             case "秋天" : System.out.println(3);break;
5             case "冬天" : System.out.println(4);break;
6             default : break;
7         }

 1         System.out.println("循环测试开始\n\n");
 2         
 3         outer:
 4         for(int i = 0;i < 6; ++i) {
 5             for(int j = 0;j < 4; ++j) {
 6                 System.out.println("i = " + i + "j = " + j);
 7                 if(j == 2)
 8                 break outer;
 9             }
10         }
11 打印结果：
12 循环测试开始
13 
14 
15 i = 0j = 0
16 i = 0j = 1
17 i = 0j = 2

 1         System.out.println("循环测试开始\n\n");
 2         
 3         outer:
 4         for(int i = 0;i < 5; ++i) {
 5             for(int j = 0;j < 3; ++j) {    
 6                 if(j == 1)
 7                 continue outer;
 8                 System.out.println("i = " + i + " j = " + j);
 9             }
10         }

循环测试开始


i = 0 j = 0
i = 1 j = 0
i = 2 j = 0
i = 3 j = 0
i = 4 j = 0

 1         System.out.println("测试for开始\n\n");
 2         
 3         for(int i = 0;i < 4; ++i) {
 4             if(i == 2)
 5             continue;
 6             System.out.println("i = " + i);
 7         }
 8         System.out.println("测试while开始\n\n");
 9         int k = 0;
10         while(k < 4) {
11             if(k == 2)
12             continue;
13             System.out.println("k = " + k);
14             ++k;//continue后，++k永远没机会执行了，循环一直执行，没死！只是无法打印k了，就像阻塞了
15         }

测试for开始


i = 0
i = 1
i = 3
测试while开始


k = 0
k = 1

//程序卡死中...