Java index out of bounds error - missing entries

Question

I'm trying to parse a csv file. A typical line looks like this:

7,118.2722833,98.61084463,94.36895546,,

The problem I'm having is that when I split the line, I'm only getting an array length of 4. I would like to have the fifth and sixth elements of the array return null, but I'm getting an index out of bounds error.

Here is a reduced version of the code:

BufferedReader br = new BufferedReader(new FileReader("FileName"));
String line = "";
String[] datum = new String[6];

while ((line = br.readLine()) != null) {
    datum = line.split(",");

    if (datum[5] != "") {
        //some statements
    }
}

Any idea why it's ignoring the last 2 commas?

Answer 1

The split method without any arguments will discard any trailing null elements. Pass a negative limit to split , and it will return an array with trailing null elements intact.

datum = line.split(",", -1);

Also, don't use != to see if it's the empty string; use

if (!("".equals(datum[5]))) {

Answer 2

Array index starts from 0, if you want 5th element you need to do datum[4] instead of datum[5]

7 --------------0
118.2722833-----1
98.61084463-----2
94.36895546-----3,
 ----------------4

Answer 3

我建议阅读有关方法java.lang.String.split(String regex, int limit)的limit参数的信息