Question

I am trying to create an array of lines in a csv file.

Example csv:

12,13,14,15
13,14,15,16
11,12,13,14

Now i want my array to contain 3 strings.

I got this:

public static String[] postcodeRows;
public static void main(String[] arg) throws Exception
{
    //read the csv file
    BufferedReader CSVFile = new BufferedReader(new FileReader(
            "C:\\Users\\randy\\Documents\\postcode csv\\exports\\all-groups.csv"));

    //count where we are in the csv file
    int csvLine = 0; 
    postcodeRows[0] = CSVFile.readLine(); // Insert the first line.
    // The while checks to see if the data is null. If it is, we've hit the end of the file. If not, process the data

    while (postcodeRows[csvLine] != null)
    {
        csvLine++;
        postcodeRows[csvLine] = CSVFile.readLine();
    }
    // Close the file once all data has been read.
    CSVFile.close();

}

Right now I get this:

Exception in thread "main" java.lang.NullPointerException
at postcodeCheckup.postcodePanel.main(postcodePanel.java:43)

Why is there a NullPointerException and how can I prevent this? The variable can’t be null, that’s checked by the while loop.

Answer 1

Yes, it can be null, you’re looking at the wrong thing. 🙂

The array postCodeRows is not initialized.

Check out http://mathbits.com/MathBits/Java/arrays/Initialize.htm.

Cheers.