Java Upside Down Triangle

The Crab

I've written a program which draws a triangle

*
**
***
****
*****

Now I need to reverse it, so it looks like

*****
****
***
**
*

below is my program but it just prints
**************************************************************************************************************************************************************************************************************************************** ad infinitum.

What am I doing wrong?

import javax.swing.JOptionPane; //import JOptionPane
class triangle1 {
    public static void main(String[] args) {
String asterix = "*";
String number=JOptionPane.showInputDialog(null, "Enter triangle size:"); //Get number1 using JOptionPane
int n = Integer.parseInt(number); //convert number string to n int
	 for (int i = n; i <= n; i--) {
 
     for (int j = n; j <= i; j--)
     {      System.out.print("*");
	 }
 
       // print a new line
       System.out.println();
   }
}
}

Webmonkey

Your condition is wrong.

Maybe something like this:

[php]
for (int i = n; j > 0; i--) {
// i will be n, n-1, n-2 etc
for (int j = 0; j < i ; j++)
{
// this loop should print horizontally
System.out.print("*");
}
}

[/php]



so they enter n = 5.

The outer loop (i will go around 5 times, 5 lines)
It will go from 5 down to 0.
So if you want to print out 5 stars first, (i), then you do a normal loop upt to i.

Remember for a for loop, set the initial condition, do the following while the condition (middle part) is true, and then after, modify the variable (i++) etc. Go over the loop like a computer would and you'll get the idea. You should know why it printed out all those *'s for infinity.

The Crab

Webmonkey wrote: »

Your condition is wrong.

Maybe something like this:

[php]
for (int i = n; j > 0; i--) {
// i will be n, n-1, n-2 etc
for (int j = 0; j < i ; j++)
{
// this loop should print horizontally
System.out.print("*");
}
}

[/php]



so they enter n = 5.

The outer loop (i will go around 5 times, 5 lines)
It will go from 5 down to 0.
So if you want to print out 5 stars first, (i), then you do a normal loop upt to i.

Remember for a for loop, set the initial condition, do the following while the condition (middle part) is true, and then after, modify the variable (i++) etc. Go over the loop like a computer would and you'll get the idea. You should know why it printed out all those *'s for infinity.

Thanks, now I have this but it produces no output except for JOptionPane

import javax.swing.JOptionPane; //import JOptionPane
class triangle {
    public static void main(String[] args) {
String asterix = "*";
String number=JOptionPane.showInputDialog(null, "Enter triangle size:"); //Get number1 using JOptionPane
int n = Integer.parseInt(number); //convert number1 string to n int
for (int i = n; i > 0; i--) {
// i will be n, n-1, n-2 etc
for (int j = 0; j < i ; j++)
  {      
     // this loop should print horizontally
     System.out.print("*");
  }
}
}
}

Adam

Well that cant be right, I just tested it and it does produce output...

Anima

[PHP]
int n = 5;

// Print N number of rows
for (int rows = 0; row < n; ++rows)
{
// Print N number of stars, decrement the number of stars each row
for (int stars = (n - rows); --stars >= 0;)
{
System.out.print ("*");
}
}
[/PHP]

Haven't tested it but it might be easier to think of it this way.

Using I's and J's for variable names looks compact but it doesn't help you read or solve the problem.

The other code posted will be more efficient but such a small difference is negligible, it's much better to code for readability.

The Crab

I got it sorted based on your advice thanks.