CODEWITHSUNDEEP
javabufferedreader
Saad Ardati
Saad Ardati

Reputation: 419

BufferedReader stops reading when reaching an empty line

I have a BufferedReader that's reading a file. The file can easily have an empty line between 2 paragraphs ex:

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The BufferedReader stops reading when it reaches the end of the first paragraph. I know why it stops as it thinks as long as an empty line is found, it thinks it's the end of the file, which is my problem.

I've been using the while loop way to iterate through the file.

I've scrambled around this problem so much I scrapped my original bufferedreader method and editted it a lot of times, but it was something like: (pseudo code, this code is not correct. notice the while loop mainly)

public static String currenttxt() throws IOException {
   BufferedReader br = new BufferedReader(new FileReader(file)); 
     try {
        while (br.readLine() != null) {
           return br.readline();
        }
     } catch (Exception e) {
        e.PrintStackTrace();
     }
}

How can I solve this issue?

Upvotes: 3

Views: 6204

Answers (2)

andih
andih

Reputation: 5603

As in the comments already mentioned your function is discarding the first line because of the while (br.readLine()) and leave the loop after reading the second line.

You should keep the line already read within some local variable.

public static String currenttxt() throws IOException {

       try (BufferedReader br = new BufferedReader(new FileReader(file))) {
       StringBuilder b = new StringBuilder();
         try {

            String line = br.readLine();
            while (line != null) {
               b.append(line);
               b.append(System.getProperty("line.separator"));
               line = br.readLine();
            }

         } catch (Exception e) {
            e.printStackTrace();
            throw e;
         }

         // remove the last line separator at the end using trim()
         return b.toString().trim();
       }

With java 7 it could be simplified to

public static String currenttxt() throws IOException{
    List<String> lines; 
    lines = Files.readAllLines(FileSystems.getDefault()
             .getPath(file.getAbsolutePath()));

    StringBuilder b = new StringBuilder();
    boolean insertNewLine = false;
    for (String line : lines) {
        if (insertNewLine) 
            b.append(System.getProperty("line.separator"));

        b.append(line);
        insertNewLine = true;       
    }

    return b.toString();
}

The second example shows one way how a trim() at the end could be avoided. Another way would be to remove the last line separator from the StringBuilder b.

Upvotes: 1

Yevgen
Yevgen

Reputation: 1667

You should initialize a varible and assign it a value every time you reading a line to avoid the problem:

    BufferedReader br = new BufferedReader(new FileReader(file));
    StringBuilder sb = new StringBuilder();
    String line = br.readLine();

    while (line != null) {
        sb.append(line);
        line = br.readLine();
    }

    return sb.toString();

If you want to preserve the empty line between paragraphs it is better to read per char: 

    BufferedReader br = new BufferedReader(new FileReader(file));
    StringBuilder sb = new StringBuilder();
    int c = br.read();

    while (c != -1) {
        sb.append(String.valueOf((char)c));
        c = br.read();
    }

    return sb.toString();

Upvotes: 1

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