第十二周作业

1.package finish;
public class finish {
    public static void main(Str

2.package finish;
    import java.util.Random;

    public class finish {
        public static void main(String[] args) {
            Random rand = new Random();
            int[] num = new int[5];
            for (int i = 0; i < num.length; i++) {
                num[i] = 20 + rand.nextInt(31);
                System.out.println(num[i]);
            }
        }
    }

ing[] args) {
        String str = "Hello World";
        char[] c = str.toCharArray();
        StringBuffer buffer = new StringBuffer();

        for (int i = str.length() - 1; i >= 0; i--) {
            if ((c[i] >= 'A') && (c[i] <= 'Z')) {
                buffer.append(String.valueOf(c[i]).toLowerCase());
            } else if ((c[i] >= 'a') && (c[i] <= 'z')) {
                buffer.append(String.valueOf(c[i]).toUpperCase());
            }
        }
        System.out.println(buffer.toString());
    }
}