Increment multidimensional array in Java

Question

I have a file to put in a multidimensional array. I have to put to [0] a date (long) and one of the dimensions must be incremented depending on the value of the second token.

Here's the code :

BufferedReader bufStatsFile  = new BufferedReader(new FileReader(statsFile));

String line = null;
List<Long[]> stats = new ArrayList<Long[]>();
stats.add(new Long[11]);
int i = 0; // will be in a loop later

while((line = bufStatsFile.readLine()) != null) {
    StringTokenizer st = new StringTokenizer(line,";");
    while(st.hasMoreTokens()) {
        stats.get(i)[0] = Long.parseLong(st.nextToken());
        stats.get(i)[Integer.parseInt(st.nextToken())]++; // Here is the problematic line.
    }
}
bufStatsFile.close();

But the incrementation doesn't work. Maybe it is because of my array which is probably not correct, but I didn't found another proper way to do that.

Emilie · Accepted Answer · 2012-09-19 07:04:06Z

1

Ok. I have found and it was, of course, stupid.

The problem was in my array declaration. I did it like that :

    List<Long[]> stats = new ArrayList<Long[]>();
    stats.add(new Long[11]);

And then, I tried to increment an Object and not a long number.

So now, I just do it like this :

    List<long[]> stats = new ArrayList<>();
    stats.add(new long[11]);

And it's perfectly working.

edited Sep 19, 2012 at 7:04

answered Sep 17, 2012 at 13:39

Emilie

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Comments

Hernan Velasquez · Accepted Answer · 2012-09-17 13:08:51Z

0

Check that the elements in your file are numbers from 0 to 10. Why are you having a List if you are only manipulating the row 0?

Which exception are your code throwing away?

answered Sep 17, 2012 at 13:08

Hernan Velasquez

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2 Comments

Emilie Over a year ago

Yes, the numbers in my file are numbers between 0 and 10. I have a NullPointerException. No, I have not explain very well. I have an unknown number of rows.

Hernan Velasquez Over a year ago

Try taking stats.get(i)[0] = Long.parseLong(st.nextToken()); out from the while(st.hasMoreTokens()) loop.

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