Program to print simple triangles in the form:
*
**
***
*****
public class Triangle {
public static void main (String args[]) {
int num_rows;
char letter = '#';
System.out.println("To print a Triangle, please enter the number");
System.out.println(" of rows to print as an integer between 1 & 26. ");
1
num_rows = (int) ReadItem.getLong();
// print one row at a time
System.out.println();
for (int i = 1; i <= num_rows; i++) {
// for each row print the characters
// the number of characters in each row is the
// same as the row number
2
for(int j = 1; j <= i; j++) {
System.out.print(letter);
}
3
System.out.print('\n'); // print the new line character
}
System.out.println("\nAll done");
}
}
/home/hayhurst/java- java Triangle
To print a Triangle, please enter the number
of rows to print as an integer between 1 & 26.
8
#
##
###
####
#####
######
#######
########
All done
Centered Triangles
public class CenteredTriangle {
public static void main (String args[]) {
int num_rows, num_blanks = 39, num_chars = 1;
char letter = '#';
System.out.println("To print a Triangle, please enter the number");
System.out.println(" of rows to print as an integer between 1 & 26. ");
num_rows = (int) ReadItem.getLong();
// print one row at a time
System.out.println();
for (int i = 1; i <= num_rows; i++) {
// for each row we need to skip enough spaces to center
// the characters in the row.. In the first row there
// is one character. Assuming 80 characters per row
// we need to skip 39 blank spaces. In each subsequent
// row, we will print 2 more characters, and skip one
// fewer space.
// print out the required number of blanks
2
for(int j = 1; j <= num_blanks; j++) {
System.out.print(' ');
}
1
// print out the required number of characters
for (int k = 1; k <= num_chars; k++) {
System.out.print(letter);
}
3
// to go to a new line print the new line character
System.out.print('\n');
// decrement the number of blanks
num_blanks--;
4
// increment the number of characters to print
num_chars += 2;
}
System.out.println("\nAll done");
}
}
The output is:
/home/hayhurst/java- java CenteredTriangle
To print a Triangle, please enter the number
of rows to print as an integer between 1 & 26.
8
#
###
#####
#######
#########
###########
#############
###############
All done
A triangle class, to print many triangles.
public class CenteredTriangleClass {
private int num_rows;
private char begin_letter;
private boolean vary_char;
public CenteredTriangleClass (int rows, char letter, boolean vary) {
num_rows = rows;
begin_letter = letter;
vary_char = vary;
}
public CenteredTriangleClass () {
num_rows = 10;
begin_letter = '#';
vary_char = false;
}
public void draw_self() {
int num_blanks = 39, num_chars = 1;
char letter = begin_letter;
// print one row at a time
System.out.println();
for (int i = 1; i <= num_rows; i++) {
// for each row we need to skip enough spaces to center
// the characters in the row.. In the first row there
// is one character. Assuming 80 characters per row
// we need to skip 39 blank spaces. In each subsequent
// row, we will print 2 more characters, and skip one
// fewer space.
// print out the required number of blanks
for(int j = 1; j <= num_blanks; j++) {
System.out.print(' ');
}
// print out the required number of characters
for (int k = 1; k <= num_chars; k++) {
System.out.print(letter);
}
// to go to a new line print the new line character
System.out.print('\n');
// decrement the number of blanks
num_blanks--;
// increment the number of characters to print
num_chars += 2;
// increment to the next character if desired
if (vary_char) letter = (char) (letter + 1);
}
System.out.println("\nAll done");
} // end draw_self
}
Program to test Class CenteredTriangleClass
public class CenteredTriangleTest {
public static void main(String args[]) {
CenteredTriangleClass small = new CenteredTriangleClass( 5, 'a', false);
CenteredTriangleClass varysmall =
new CenteredTriangleClass( 5 , 'a', true);
CenteredTriangleClass large =
new CenteredTriangleClass( 10, '*', true);
small.draw_self();
varysmall.draw_self();
large.draw_self();
}
}
/home/hayhurst/java- java CenteredTriangleTest
a
aaa
aaaaa
aaaaaaa
aaaaaaaaa
All done
a
bbb
ccccc
ddddddd
eeeeeeeee
All done
*
+++
,,,,,
------.........
///////////
0000000000000
111111111111111
22222222222222222
3333333333333333333
All done