Empty element in List causing Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range

Question

I am working with a CSV file that looks like this https://plus.google.com/u/0/photos/photo/115135191238195349859/6559552907258825106

as you can see in the coloum "date_sold" there are gaps

I am trying to shorten the dates to just the month (the first two ints of the whole date with this method:

public static void getTotalSales(){

    int w = 0; 
    while (w < date_sold.size()){ 
// if the current element is smaller than the size of the 
        if((date_sold.get(w)) != "" ){ 
// if the element in the array is empty (might be the problem)
      date_sold.set(w,((date_sold.get(w)).substring(0,2)));
// trim the string at the element to two characters
     }
    w = w + 1;
  }
System.out.println(date_sold);
}

This prints out working for the first element from "date_sold" to "da" but then I get a

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range

I would like to skip over empty elements but not get rid of them as the indexing of empty elements is important to me

Possible duplicate of [What is the difference between == vs equals() in Java?](https://stackoverflow.com/questions/7520432/what-is-the-difference-between-vs-equals-in-java) — Mạnh Quyết Nguyễn, May 28 '18 at 05:08
But you are comparing strings with `!=`, which is invalid. Also, you should be checking that the `length()` is at least 2 before doing the `substring`. You might also want to `trim()` the string. — David Conrad, May 28 '18 at 05:13
`date_sold.get(w)).substring(0,2)` requires your string length is at least 2. — Mạnh Quyết Nguyễn, May 28 '18 at 05:13
`if (!date_sold.get(w).equals(""))` you can find this in any introductory Java tutorial. But what you really want is `if (date_sold.get(w).length() >= 2)` — David Conrad, May 28 '18 at 05:17
@DavidConrad i dont know what i am doing wrong https://plus.google.com/u/0/photos/photo/115135191238195349859/6560498045248873010 — Kabira Suleman, May 28 '18 at 05:24
I don't either. Are you getting an exception? The wrong answer? If you're trying to extract the month from dates like "10/30/2017" and "5/16/2017" then taking the first two characters obviously won't work since the month isn't always two characters. — David Conrad, May 28 '18 at 05:25
A couple of suggestions: `date.split("/")` will split it into a `String[]` on the slashes. The month will be in entry `0`. Or `date.indexOf("/")` will find the offset of the first slash, or `-1` if there isn't one. That index can then be used in a `substring`. — David Conrad, May 28 '18 at 05:31
yes that sounds very promising, thank you for your time good sir — Kabira Suleman, May 28 '18 at 05:34

Empty element in List causing Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range

0 Answers0