Storing integers inside a data file into an array Java

Question

I am trying to store integers from a data file into an array. I am using Java Eclipse IDE.

Here is my data file:

(oddsAndEvens.dat)

2 4 6 8 10 12 14
1 2 3 4 5 6 7 8 9
2 10 20 21 23 24 40 55 60 61

Here is my code:

import java.io.File;
import java.util.Arrays;
import java.io.IOException;
import java.util.Scanner;

public class OddsAndEvens {
    public static void main(String[] args) throws IOException {
        Scanner file = new Scanner(new File("oddsAndEvens.dat"));
        int count, num = 0;
        int[] newRay = null;
        while (file.hasNext()) {
            String line = file.nextLine();
            Scanner chop = new Scanner(line);
            count = 0;
            while (chop.hasNextInt()) {
                num = chop.nextInt();
                count++;

                newRay = new int[count];
                int j = 0;
                for (int i = 0; i < count; i++) {
                    newRay[j] = num;
                    j++;
                }
            }
            System.out.println(Arrays.toString(newRay));
        }
    }
}

My output is coming out as this:


[14, 14, 14, 14, 14, 14, 14]
[9, 9, 9, 9, 9, 9, 9, 9, 9]
[61, 61, 61, 61, 61, 61, 61, 61, 61, 61]

What I am looking for is this:

[2, 4, 6, 8, 10, 12, 14]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
[2, 10, 20, 21, 23, 24, 40, 55, 60, 61]

How would I turn these sets of numbers on each line from my data file into an array? Is there an easier way to do it?

score 0 · Answer 1 · answered Nov 01 '19 at 15:47

Your problem is that you have one loop reading all the numbers and assigning them to num, and another loop storing num at every index in the array. Each array component can only hold one number at a time, so each time they're assigned, their previous values are overwritten (i.e. lost), so finally the array holds only the last number that was read from the scanner.

To fix this, you should use just one loop, which reads one number and stores it in the array before the next iteration of the loop reads the next number. You should not have a loop which writes the same value at every index in the array.

score 0 · Accepted Answer · answered Nov 01 '19 at 15:53

you can read each line and store it in a string array by splitting it with space and then convert it to integer, here's how you can do it.\

import java.io.File;
import java.util.Arrays;
import java.io.IOException;
import java.util.Scanner;

public class OddsAndEvens {
    public static void main(String[] args) throws IOException {
        Scanner file = new Scanner(new File("oddsAndEvens.dat"));
        int[] newRay = null;
        while (file.hasNext()) {
            String line = file.nextLine();
            String[] str = line.split("\\s+");
            newRay = new int[str.length];
            for (int i = 0; i < str.length; i++) {
                newRay[i] = Integer.valueOf(str[i]);
            }
            System.out.println(Arrays.toString(newRay));
        }
    }
}

Storing integers inside a data file into an array Java

2 Answers2