The document discusses using nested for loops to print patterns of asterisks in the shape of diamonds. It demonstrates how to write nested for loops to print the top and bottom halves of diamonds of different sizes by varying the number of iterations and spaces/asterisks printed on each line. It also shows how to define a class constant SIZE to parameterize the size of the diamonds, so that different diamond sizes can be generated by changing the value of SIZE.

1. Examples:
Nested For Loops and
Class Constants
AP Computer Science A
Building Java Programs, 3rd Edition

2. In this chapter:
● Following code using variable tables
● Writing nested for loops
● Using class constants

3. Variable
Tables

4. for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= i; j++) {
System.out.print("*");
}
System.out.println();
}
i j
1 1
2 1
2
3 1
2
3
*
**
***

5. Nested For
Loops

6. *****
*****
*****
for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= 5; j++)
{
System.out.print("*");
}
System.out.println();
}

7. *
**
***
for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= i; j++)
{
System.out.print("*");
}
System.out.println();
}

8. ***
**
*
for (int i = 3; i >= 1; i--) {
for (int j = 1; j <= i; j++)
{
System.out.print("*");
}
System.out.println();
}

9. ***
****
*****
for (int i = 3; i <= 5; i++) {
for (int j = 1; j <= i; j++)
{
System.out.print("*");
}
System.out.println();
}

10. *****
****
***
for (int i = 5; i >= 3; i--) {
for (int j = 1; j <= i; j++)
{
System.out.print("*");
}
System.out.println();
}

11. ***
*******
***********
for (int i = 3; i <= 11; i += 4) {
for (int j = 1; j <= i; j++)
{
System.out.print("*");
}
System.out.println();
}

12. ***********
*******
***
for (int i = 11; i >= 3; i -= 4) {
for (int j = 1; j <= i; j++)
{
System.out.print("*");
}
System.out.println();
}

13. ****++
***++++
**++++++
for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= i - 1; j++)
{
System.out.print(" ");
}
for (int j = 1; j <= 5 - i; j++) {
System.out.print("*");
}
for (int j = 1; j < 2 * i; j++) {
System.out.print("+");
}
System.out.println();
row #
(i)
# of
spaces
# of
stars
# of
pluses
1 0 4 2
2 1 3 4
3 2 2 6
i - 1 5 - i i * 2
Function Method

14. Class
Constants

15. public class ClassConstants {
public static final int SIZE = value;
//methods go here
}
Class Constants

16. *
***
*****
*******
*****
***
*
Size 4
row #
(i)
# of
spaces
# of
stars
1 3 1
2 2 3
3 1 5
4 0 7
5 1 5
6 2 3
7 3 1
*
***
*****
***
*
Size 3
row #
(i)
# of
spaces
# of
stars
1 2 1
2 1 3
3 0 5
4 1 3
5 2 1

17. *
***
*****
*******
public static void topHalf() {
for (int i = 1; i <= 4; i++) {
for (int j = 1; j <= 4 - i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
}
row #
(i)
#
spaces
#
stars
1 3 1
2 2 3
3 1 5
4 0 7
Size 4 Top Half
Size 4 Bottom Half
*****
***
*
row #
(i)
#
spaces
#
stars
1 1 5
2 2 3
3 3 1
public static void bottomHalf() {
for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= 7 - 2 * i; j++) {
System.out.print("*");
}
System.out.println();
}
}
4 - i 2 * i - 1
i 7 - 2 * i

18. *
***
*****
public static void topHalf() {
for (int i = 1; i <= 3; i++) {
for (int j = 1; j <= 3 - i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
}
row #
(i)
#
spaces
#
stars
1 2 1
2 1 3
3 0 5
Size 3 Top Half
Size 3 Bottom Half
***
*
row #
(i)
#
spaces
#
stars
1 1 3
2 2 1
public static void bottomHalf() {
for (int i = 1; i <= 2; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= 5 - 2 * i; j++) {
System.out.print("*");
}
System.out.println();
}
}i 5 - 2 * i
3 - i 2 * i - 1

19. public static void topHalf() {
for (int i = 1; i <= SIZE; i++) {
for (int j = 1; j <= SIZE - i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
}
Putting SIZE into
topHalf()
public static void topHalf() {
for (int i = 1; i <= SIZE; i++) {
for (int j = 1; j <= SIZE - i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
}
*
***
*****
*
***
*****
*******
SIZE = 3
SIZE = 4

20. Putting SIZE into
bottomHalf()
***
*
*****
***
*
SIZE = 3
SIZE = 4
public static void bottomHalf() {
for (int i = 1; i <= SIZE - 1; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= (2 * SIZE - 1) - 2 * i; j++) {
System.out.print("*");
}
System.out.println();
}
}
public static void bottomHalf() {
for (int i = 1; i <= SIZE - 1; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
for (int j = 1; j <= (2 * SIZE - 1) - 2 * i; j++) {
System.out.print("*");
}
System.out.println();
}
}

21. public class ClassConstantDiamonds {
public static final int SIZE = 3; //or 4
public static void main(String[] args) {
topHalf();
bottomHalf();
}
public static void topHalf() {
for (int i = 1; i <= SIZE; i++) {
for (int j = 1;
j <= SIZE - i; j++) {
System.out.print(" ");
}
for (int j = 1;
j <= 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
}
public static void bottomHalf() {
for (int i = 1; i <= SIZE - 1; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
for (int j = 1;
j <= (2 * SIZE - 1) - 2 * i;
j++) {
System.out.print("*");
}
System.out.println();
}
}
}

22. *
Size 5
Size 0 or less
Different Values for SIZE
Size 1
*
***
*
Size 2
*
***
*****
*******
*********
*******
*****
***
*
(nothing printed)