/**

* Demonstrates uses of loops.

*/

public class Loops {

public static void countdown(int n) {

while (n > 0) {

System.out.println(n);

n = n - 1;

}

System.out.println("Blastoff!");

}

public static void sequence(int n) {

while (n != 1) {

System.out.println(n);

if (n % 2 == 0) { // n is even

n = n / 2;

} else { // n is odd

n = n * 3 + 1;

}

}

}

public static void plusplus() {

int i = 1;

while (i <= 5) {

System.out.println(i);

i++; // add 1 to i

}

}

public static void appreciate() {

int i = 2;

while (i <= 8) {

System.out.print(i + ", ");

i += 2; // add 2 to i

}

System.out.println("Who do we appreciate?");

}

public static void appreciate2() {

for (int i = 2; i <= 8; i += 2) {

System.out.print(i + ", ");

}

System.out.println("Who do we appreciate?");

}

public static void loopvar() {

int n;

for (n = 3; n > 0; n--) {

System.out.println(n);

}

System.out.println("n is now " + n);

}

public static void nested() {

for (int x = 1; x <= 10; x++) {

for (int y = 1; y <= 10; y++) {

System.out.printf("%4d", x * y);

}

System.out.println();

}

}

public static void main(String[] args) {

System.out.println("\ncountdown");

countdown(3);

System.out.println("\nsequence");

sequence(10);

System.out.println("\nplusplus");

plusplus();

System.out.println("\nappreciate");

appreciate();

System.out.println("\nappreciate2");

appreciate2();

System.out.println("\nloopvar");

loopvar();

System.out.println("\nnested");

nested();

}

}