The null is because it's reading past the last line of the file. So when it has read the last line the 'while' is true, then it reads the next line(one after last one) then when you access the length...

upload the data files if they are not too big, we'll see if we can help.

'tmp' string might be null. put a check like this after you do the 'readLine' and try


if(tmp != null)
{
//your code
}