从文件读取返回null

Question

I'm having an issue with this method. It's returning a null value, and I'm not sure how to fix it. I saw someone else explaining that the loop doesn't stop until null is reached and therefore returns null, but I don't understand how to get around this. Thanks in advance

public static int[] readFile(File file) throws IOException {

    Scanner fileRead = new Scanner(file);
    int a = 0;
    while(fileRead.hasNext()) {    
        a++;
        fileRead.nextLine();
    }
    String[]pieces = new String[a];
    while (fileRead.hasNext()) { // i think the error is happening right here
        String line = fileRead.nextLine();
    pieces = line.split(",");


    }
    fileRead.close();
    int[] piecesNum = new int [pieces.length];
    for (int b = 0; b < pieces.length; b++) {
        piecesNum[b] = Integer.parseInt(pieces[b]); // line 86

    }
    return piecesNum;

The error

java.lang.NumberFormatException: null
    at java.lang.Integer.parseInt(Integer.java:542)
    at java.lang.Integer.parseInt(Integer.java:615)
    at Proj5.readFile(Proj5.java:86)
    at Proj5.main(Proj5.java:23)

Answer 1

The outcome of pieces[b] is null and that cannot be parsed to Integer .

Try one of the following:

1. Handle the exception

    try{ piecesNum[b] = Integer.parseInt(pieces[b]); } catch (NumberFormatException e) { // do something } 

2. Verify that content is not null and is a digit

    String piece = pieces[b]; if(piece != null && piece.matches("\\\\d*")){ piecesNum[b] = Integer.parseInt(piece); }