Question

I am trying to convert a String into an ArrayList. For example, my Struts2 webapp returns this String named row in a format similar to this:

[A, BB, CCC, DDDD, 1, 0, 1] (something along those lines)

I need to convert them into an ArrayList so I can prepopulate some forms in another JSP page. I hardcoded a method to convert such Strings into list form:

        StringBuffer rowBuffer = new StringBuffer(row);
        int startIndex = 0;
        int endIndex = rowBuffer.indexOf(",") - 1;
        rowBuffer.deleteCharAt(rowBuffer.indexOf("["));
        rowBuffer.deleteCharAt(rowBuffer.indexOf("]"));
        while(startIndex != -1 && endIndex != -1 && startIndex < endIndex)
        {
          String subString = rowBuffer.substring(startIndex, endIndex);

       if(subString.contains(","))
       {
          rowList.add(" ");
          startIndex = endIndex + 1;
          endIndex = rowBuffer.indexOf(",", startIndex);
       }

       else
       {
        rowList.add(subString);
        startIndex = endIndex + 2;
        endIndex = rowBuffer.indexOf(",", startIndex + 1);
       }

       if(endIndex == -1)
       {
          rowList.add(rowBuffer.substring(startIndex));
          break;
       }
    }

This works fine in cases where all the fields are populated. However, lets say I have a String that looks like this: [A, BB, , , 1, 0, 0] (the 3rd and 4th fields are missing), then I get something that doesn’t work (the blank elements don’t register correctly, and the size of the list is 6, when it should be 7). Is there a more elegant solution than hardcoding? If not, could someone point me in the right direction on how to handle cases with blank fields? Thanks!

Answer 1

Well I changed my code a bit and made it work (it’s probably far from the most elegant solution, but it works for me…

    StringBuffer rowBuffer = new StringBuffer(row);
    int startIndex = 0;
    int endIndex = rowBuffer.indexOf(",") - 1;
    rowBuffer.deleteCharAt(rowBuffer.indexOf("["));
    rowBuffer.deleteCharAt(rowBuffer.indexOf("]"));
    while(startIndex != -1 && endIndex != -1 && startIndex < endIndex)
    {
      String subString = rowBuffer.substring(startIndex, endIndex);

       if(subString.contains(","))
       {
          rowList.add(" ");
          startIndex = endIndex - 1;
          endIndex = rowBuffer.indexOf(", ", startIndex + 1);
       }

       else
       {
         if(subString.equals("1"))
             rowList.add("True");
         else if(subString.equals("0"))
             rowList.add("False");
         else
          rowList.add(subString);
        startIndex = endIndex + 2;
        endIndex = rowBuffer.indexOf(",", startIndex + 1);
       }

       if(endIndex == -1)
       {
          if(subString.equals("1"))
             rowList.add("True");
          else if(subString.equals("0"))
             rowList.add("False");
          break;
       }
    }