A simple Array Problem

[Sivaraman Lakshmanan]

hai all,
I have a simple array problem. I am not sure where I am going wrong. please review my code and correct me.
my code is:

public String[][] split(String[] content, int len)
{
if(content!=null)
{
  for(int i=0; i<content.length; i++)
  {
  String item[] = sql.tokenize(content[i], ",");
  strMenucnt = new String[len][item.length];
  strMenucnt[i] = item;
  System.out.print("for: " + i +" => " + strMenucnt[i][0]+ "\t" + strMenucnt[i][1] + "\t"); // Printing - 1
  }
   System.out.println("after: the while  ....");
   for(int a=0; a<strMenucnt.length;a++)
   {
      for(int b=0; b<strMenucnt[0].length;b++)
      {
        System.out.print(a+"/"+ b + " => "  + strMenucnt[a][b]); //printing -2
        System.out.print("\t");
      }
      System.out.print("\n");
   }
 }
 return strMenucnt;
}

Here in the above code when I print for the first time (Printing -1) I get the values of the array correctly. but when I print for the second time this same array (printing - 2) all the vales expect for the last row is null.
I am give the out put what I got below

  
//printing -1
for: 0 => 1     1       for: 1 => 2     2       for: 2 => 3     3       for: 3 => 4     4       for: 4 => 5     5       for: 5 => 6     6
after: the while  ....
//printing -2
0/0 => null     0/1 => null
1/0 => null     1/1 => null
2/0 => null     2/1 => null
3/0 => null     3/1 => null
4/0 => null     4/1 => null
5/0 => 6        5/1 => 6

atleast if everything comes as null, its fine I am not sure how I am getting the values for the last row...
please help me to sort out the problem.
Thanks in advance.
Sivaraman.L

[Stefan Wagner]

Originally posted by Sivaraman Lakshmanan:

   for(int a=0; a<strMenucnt.length;a++)
   {
      for(int b=0; b<strMenucnt[0].length;b++)

shouldn't it be:

  
   for(int a=0; a<strMenucnt.length;a++)
   {
      for(int b=0; b<strMenucnt[a].length;b++)

[Sivaraman Lakshmanan]

hi Wagner,
even though I give the array index as u told.. The output is the same.
siva

[Eddie Vanda]

Hi Sivaraman
I have made a couple of changes to fix your code and a couple of additions to test it:
I moved the strMenucnt declaration outside of the for loop as you were overriding each instance with the next instance of the main lhs subscript. I left the declaration of the rhs subscript in the for loop. I also changed the lhs subscript in your print loop to match the actual element since my test had different numbers of elements for different rows.

import java.util.*;
class Main {
  public String[][] split(String[] content, int len){
    String [][] strMenucnt = null;
    if(content!=null) {
      strMenucnt = new String[content.length][];
      for(int i=0; i<content.length; i++) {
        String item[] = tokenize(content[i], ",");
        strMenucnt [i] = new String [item.length];
        strMenucnt[i] = item;
        System.out.print("for: " + i +" => " + strMenucnt[i][0]+ "\t" + strMenucnt[i][1] + "\t"); // Printing - 1
      }
      System.out.println("after: the while ....");
      for(int a=0; a<strMenucnt.length;a++) {
        for(int b=0; b<strMenucnt[a].length;b++) {
          System.out.print(a + "/"+ b + " => " + strMenucnt[a][b]); //printing -2
          System.out.print("\t");
        }
        System.out.print("\n");
      }
    }
    return strMenucnt;
  }
  String [] tokenize (String s, String t) {
    int n = 0;
    StringTokenizer st = new StringTokenizer (s, t);
    String [] rt = new String [st.countTokens ()];
    while (st.hasMoreTokens()) {
      rt [n++] = st.nextToken();
    }
    return rt;
  }
  public static void main (String [] args) {
    String [] t = {"Its, a, nice, day", "last, string"};
    Main main = new Main ();
    main.split (t, t.length);
  }
}

[Sivaraman Lakshmanan]

Dear Eddie Vanda,
you have really solved the problem the big headache I had. I was struggling for the past 3 days to solve the problem. thanks you very much.
can u sum up and tell me what actually went wrong in my code, so that I will be carful in my future.
Once again Thanks for your excellent answer.
regards,
sivaraman.L

[Eddie Vanda]

Hi Sivaraman,
It's a pleasure. I think the main problem is that two dimensional arrays in java do not follow your traditional mathematical concept or c's layout.
The left hand side (lhs) subscript could be viewed as a row of single subscript array holders. That's the bit that got overridden by each iteration of your inner for loop, so only the last row was valid. The "item" array was then added to each of your row (lhs) holders. I just split the array declaration so that rows were declared outside that loop.
You could think of the right hand side (rhs) subscript as being the columns of your array. Each is a separate single dimension array in its own right.
Good luck.
Ed