import java.util.Random; public class Demo { private static final Random r = new Random(); public static void main(String[] args) { int val = 5; while (val<= 100) { System.out.printf("%-4d", r.nextInt(20) * 1); if (val % 5 == 0) { System.out.println(); } val++; } System.out.println(); val = 20; while (val<= 100) { System.out.printf("%-4d", r.nextInt(10 * (20))); if (val % 5 == 0) { System.out.println(); } val++; } } }