第十二周作业。

 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 }