empty array to convert file to array

Question

I try to convert a file to an array of integers, do not know where my mistake is that when I print the array empty array throws

I leave my method , thanks you

public int[] ConvertToArray(File xd) throws IOException {     

 String sCadena;int i=0;
    int[]array;
    FileReader fr = new FileReader(xd); 
    BufferedReader bf = new BufferedReader(fr);
    int lNumeroLineas = 0;
    while ((sCadena = bf.readLine())!=null) {
        lNumeroLineas++;
    }
    array = new int[lNumeroLineas];
    while ((sCadena = bf.readLine())!=null) {
        lNumeroLineas++;
        array[i]=Integer.parseInt(sCadena);
        i++;
    }

    for (int j = 0; j < array.length; j++) {
        System.out.println(array[i]);
    }
    return array;
}

rhitz · Accepted Answer · 2015-11-19 06:10:53Z

1

You are already at the end of file after your first while loop completes.

So reading from BufferedReader object bf again after first while loop ends will always give you null(End of file) and second iteration will never run.

Also in the for loop you are printing array[i] however for loop is iterating over j variable

You can do it like this with help of ArrayList:

public int[] ConvertToArray(File xd) throws IOException {     

 String sCadena;

    ArrayList<Integer> array = new ArrayList();

    FileReader fr = new FileReader(xd); 
    BufferedReader bf = new BufferedReader(fr);
    int lNumeroLineas = 0;
    while ((sCadena = bf.readLine())!=null) {
        lNumeroLineas++;
        array.add(Integer.parseInt(sCadena.trim())); //always recomended to trim(); to remove trailing whitespaces.
    }

    for (int j = 0; j < array.size(); j++) {
        System.out.println(array.get(j));
    }
    return covertIntegers(array);
}

Edited: If you want to send int[] instead of ArrayList<Integer> without using any external libraries.

    public static int[] convertIntegers(List<Integer> integers)
{
    int[] ret = new int[integers.size()];
    for (int i=0; i < ret.length; i++)
    {
        ret[i] = integers.get(i).intValue();
    }
    return ret;
}

edited Nov 19, 2015 at 6:10

answered Nov 19, 2015 at 5:52

rhitz

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2 Comments

rhitz Over a year ago

In accordance to what ? Do you want to return an integer array from the above method?

rhitz Over a year ago

Glad to help ! Please accept the answer if your problem is solved, as it helps everyone who visits this question in future.

Zbynek Vyskovsky - kvr000 · Accepted Answer · 2015-11-19 05:42:08Z

0

You are reading the file with two loops but open only once. Reopen the file reader before the second while and it will work.

answered Nov 19, 2015 at 5:42

Zbynek Vyskovsky - kvr000

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1 Comment

Deibis J. Over a year ago

@ZbynekThank you very much for your contribution

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