1 package Pro1;
2
3 public class Test {
4 public static void main(String[] args) {
5 String str = "Hello World";
6 char[] c = str.toCharArray();
7 StringBuffer buffer = new StringBuffer();
8
9 for (int i = str.length() - 1; i >= 0; i--) {
10 if ((c[i] >= 'A') && (c[i] <= 'Z')) {
11 buffer.append(String.valueOf(c[i]).toLowerCase());
12 } else if ((c[i] >= 'a') && (c[i] <= 'z')) {
13 buffer.append(String.valueOf(c[i]).toUpperCase());
14 }
15 }
16 System.out.println(buffer.toString());
17 }
18 }
1 package pro2;
2 import java.util.Random;
3 public class Test2 {
4 public static void main(String[] args) {
5 Random rand = new Random();
6 int[] num = new int[5];
7 for (int i = 0; i < num.length; i++) {
8 num[i] = 20 + rand.nextInt(31);
9 System.out.println(num[i]);
10 }
11 }
12 }
