Pfthb

I made a 2D array containing integer values and want to convert it into a string, but I'm really confused on what I'm able to put into //something to get the output I want.

public static void main(String args) {
 final int test = 1, 6, 11, 16, 21, 
 2, 7, 12, 17, 22, 
 3, 8, 13, 18, 23, 
 4, 9, 14, 19, 24, 
 5, 10, 15, 20, 25 ;
 System.out.println(TwoDOneD.DownNUp(test));

public static String DownNUp(int test) 
 String res = "";
 for (int r = 0; r < test[0].length; r++) 
 for (int c = 0; c < test.length; c++) 
 if (c % 2 == 1) 
 //something
 else 
 res += test[c][r] + " ";
 
 
 
 return res;

The output I'm trying to get is why I have (c % 2 == 1); in every odd column, it's supposed to go down, and in every even column, it goes right back up.

1 2 3 4 5 10 9 8 7 6 11 12 13 14 15 20 19 18 17 16 21 22 23 24 25

You need to change iteration direction, based on c % 2 == 0

public static void main(String args) 

 final int test = 1, 6, 11, 16, 21, 
 2, 7, 12, 17, 22, 
 3, 8, 13, 18, 23, 
 4, 9, 14, 19, 24, 
 5, 10, 15, 20, 25 ;
 System.out.println(downUp(test));


public static String downUp(int test) 
 String res = "";
 for (int c = 0; c < test[0].length; c++) 

 if (c % 2 == 0) 
 for (int r = 0; r < test.length; r++) 
 res += test[r][c] + " ";
 

 else 

 for (int r = test.length -1 ; r >=0 ; r--) 
 res += test[r][c] + " ";
 
 
 
 return res;

A side note: it would be better implemented using a StringBuilder like so:

public static String downUp(int test) 

 StringBuilder res = new StringBuilder();

 for (int c = 0; c < test[0].length; c++) 

 if (c % 2 == 0) 
 for (int r = 0; r < test.length; r++) 
 res.append(test[r][c]).append(" ");
 

 else 

 for (int r = test.length -1 ; r >=0 ; r--) 
 res.append(test[r][c]).append(" ");
 
 
 
 return res.toString();

i think this is that you want:

public static String DownNUp(int test) 
 String res = "";
 for (int r = 0; r < test[0].length; r++) 
 for (int c = 0; c < test.length; c++) 

 if (r % 2 != 0) 
 res += test[test.length - 1 - c][r] + " ";
 else 
 res += test[c][r] + " ";
 
 
 
 return res;