第十二周作业

package awm;

public class text {

	public static void main(String[] args) {
		String s = "HelloWorld";
		char[] a = s.toCharArray();
		StringBuffer buffer = new StringBuffer();
		for (int i = s.length() - 1; i >= 0; i--) {
			if ((a[i] >= 'A') && (a[i] <= 'Z')) {
				buffer.append(String.valueOf(a[i]).toLowerCase());
			} else if ((a[i] >= 'a') && (a[i] <= 'z')) {
				buffer.append(String.valueOf(a[i]).toUpperCase());
			}
		}
		System.out.println(buffer.toString());
	}

}

　　

package awm;

import java.util.Random;

public class text {

	public static void main(String[] args) {

		Random r = new Random();
		int[] a = new int[5];
		for (int i = 0; i < a.length; i++) {
			a[i] = 20 + r.nextInt(31);
			System.out.println(a[i]);
		}

	}
}