Reading data from file without manually inputing the length it the array

Question

Please I will like to adjust this code that reads integers from a file. I will like the code to detect the number (n) of the dataset instead of having to put in figures manually as done below (4000 )

double[] tall = new double[4000];

public class Extracto {

    public static void main(String[] args) throws IOException {

        File fil = new File("C:\\Users\\Desktop\\kaycee2.csv");
        FileReader inputFil = new FileReader(fil);
        BufferedReader in = new BufferedReader(inputFil);
        double[] tall = new double[4000];
        String s = in.readLine();
        int i = 0;
        while (s != null) {
            // Skip empty lines.
            s = s.trim();
            if (s.length() == 0) {
                continue;
            }
            tall[i] = Double.parseDouble(s); // This is line 19.
            //  System.out.println(tall[i]);
            s = in.readLine();
            i++;

        }

I am expecting the adjusted code to obtain the data length without manually putting it in like in as shown in the code below for the 4000 length.

double[] tall = new double[4000];

Use a list instead of an array

Thomas Weller
– Thomas Weller

2019-08-26 16:14:58 +00:00
Commented Aug 26, 2019 at 16:14 — Thomas Weller
– Thomas Weller, Commented Aug 26, 2019 at 16:14

Angel Koh · Accepted Answer · 2019-08-26 16:20:40Z

3

As Thomas mentioned, use a list, instead of an array.

    File fil = new File("C:\\Users\\Desktop\\kaycee2.csv");
    FileReader inputFil = new FileReader(fil);
    BufferedReader in = new BufferedReader(inputFil);
    ArrayList<Double> tall = new ArrayList<>();
    while(in.ready()){ 
        String s = in.readLine().trim();
        if(!s.isEmpty()){
           tall.add(Double.parseDouble(s);
        } 
    }

your codes can be further compacted if you use a list. also do add a try-catch in the event when the String read is not a number.

answered Aug 26, 2019 at 16:20

Angel Koh

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1 Comment

Jonatino Over a year ago

Thank you very much @ Angel

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