How to manage blank lines in Files

Question

public ArrayList makeList(String FileStr, File mainFile) {
    ArrayList file_reader = new ArrayList();
    boolean flag = false;

    try {
        if (FileStr.contains(".txt")) {
            BufferedReader bufferedReader = new BufferedReader(new FileReader(mainFile));
            String thisLine = null;
            while ((thisLine = bufferedReader.readLine()) != null) {
                if (thisLine != null && !thisLine.isEmpty()) {
                    flag = true;
                    file_reader.add(thisLine);
                }
            }
            if (bufferedReader != null) {

                bufferedReader.close();
            }

        }
    } catch (IOException ex) {
        // Logger.getLogger(BulkUpload.class.getName()).log(Level.SEVERE, null, ex);
        ex.printStackTrace();
    }


    if (flag) {
        return file_reader;
    } else {
        return null;
    }
}

I have written this code to read lines from the file, but if there is a blank line in between 5000 records, the front end goes blank.

How can I manage this blank space?

I dont want to stop reading my files even though there is a blank space or line in between records

Are you sure the blank line is the problem? I don't see anything in your code that suggests that it would stop reading if it encounters a blank line. — Robby Cornelissen, Aug 30 '14 at 05:36
Can you show us your stack trace? It's hard to know why your screen is going blank. And I think @RobbyCornelissen is right, it seems that it has nothing to do with blank lines. — lxcky, Aug 30 '14 at 05:50

score 1 · Answer 1 · answered Aug 30 '14 at 05:23

1

if (thisLine.trim().isEmpty())

answered Aug 30 '14 at 05:23

Alex Suo

2,977
1
14
22

Prazzy Kumar · Answer 2 · 2014-08-30T06:22:46.103

1

Blank lines don't give you null. They just give you empty string or blank spaces. You can avoid them using two ways.

1st way

 if(thisLine.trim().equals(""))
        continue;

2nd Way

if(thisLine.trim().length()<1)
        continue;

Hope that helps.

edited Aug 30 '14 at 06:22

answered Aug 30 '14 at 05:44

Prazzy Kumar

994
1
11
16

1

I'm sorry, but that's all kinds of wrong. In your logic, `"A"` qualifies as an empty string. There is an `isEmpty()` method. Why not use it? – Robby Cornelissen Aug 30 '14 at 05:51
You should read this . The answer is precise. no need of downvotes! [link](http://stackoverflow.com/questions/3321526/should-i-use-string-isempty-or-equalsstring) – Prazzy Kumar Aug 30 '14 at 06:09
1

Where does it say in that question that strings with a length smaller than 2 are empty strings? Your answer is wrong. Try it yourself: `if("a".trim().length() < 2) System.out.println("Empty string?");` – Robby Cornelissen Aug 30 '14 at 06:11
My bad. It should be < 1 or == 0. – Prazzy Kumar Aug 30 '14 at 06:22
2

Like I said. Better to use `isEmpty()` to avoid this type of bug. – Robby Cornelissen Aug 30 '14 at 06:23

How to manage blank lines in Files

2 Answers2