How do you call a function in a for loop?

Question

In the last method I'm trying to call printPattern inside of a for loop, but I have no idea what I'm doing wrong. I'm using BlueJ, so I'm not sure if the code will be different in Eclipse.

Here's the program:

public class recursion
{

    private int count;

    private String printPattern(int count, int itterations)
    {
        int i;
        String line= "";

        for(i=0; i <= count; i++)
        {
            if (i > itterations)
            {
                line = line + i;
            }
            else {line = line + "*";}
        }
        line = line + reverseLine(line);
        return line;
    }

    private String reverseLine (String line)
    {
        int size;
        String linerev = "";
        for (int i = line.length() - 1; i >= 0; i--)
        {
            linerev= linerev + line.charAt(i);
        }
        return linerev;
    }

    private void addLineandReverse (int n)
    {
        int w= n;
        //for loop
        //calls function print pattern
        //add itteration ++
        //prints out
        for (n= 9; n <= printPattern; n++)
        {
            System.out.println();
        }
    }
}

Here is what I wish the output of the program to look like:

      123456789987654321
      *2345678998765432*
      **34567899876543**
      ***456789987654***
      ****5678998765****
      *****67899876*****
      ******789987******
      *******8998*******
      ********99********
      ******************

Answer 1

You are using the function as limit for the stop condition of the for loop. But that seems wrong as I don't think the function is ment to return the result for a condition, it returns a string.

I'm not sure what you are trying to accomplish with calling the function. and why you are reassigning n to 9.

Either way to call the printPattern method you have to use this syntax:

printPattern(aNumber, anotherNumber)

Code that would work (but probably not output what you want) would be:

public void addLineandReverse (final int n)
{
   //for loop 
   // calls function print pattern
   // add itteration ++
   //prints out
   for (int i = 0; i <= n; ++n) {
     System.out.println(printPattern(w, n));
   }
}

Ok I took your requirements and adjusted your code and stayed as close as I could to your design (its not the design that I would take to tackle this problem but it works.

public class Recursion {

    public static void main(String[] args) {
        final Integer count = 9;
        final Recursion recursion = new Recursion(count);
        recursion.addLineAndReverse();
    }

    public Recursion(final Integer count) {
        this.count = count;
    }

    private final int count;

    public String printPattern(final int lineNumber) {

        String line= "";

        for(int i = 1; i <= count; ++i){
            if (i >= lineNumber) {
                line += i;
            } else {
                line += "*";
            }
        }
        line += reverseLine(lineNumber);
        return line;
    }

    public String reverseLine(final int lineNumber)
    {

        String line= "";

        for(int i = count; i >= 1; --i){
            if (i >= lineNumber) {
                line += i;
            } else {
                line += "*";
            }
        }

        return line;
    }

    public void addLineAndReverse(){
        for (int i = 1;  i <= count + 1; ++i){
            System.out.println(printPattern(i));
        }

    }

}