Buffered Reader read text until character

Question

I am using a buffered reader to read in a file filled with lines of information. Some of the longer lines of text extend to be more than one line so the buffered views them as a new line. Each line ends with ';' symbol. So I was wondering if there was a way to make the buffered reader read a line until it reaches the ';' then return the whole line as a string. Here a how I am using the buffered reader so far.

  String currentLine;
        while((currentLine = reader.readLine()) != null) {
            // trim newline when comparing with lineToRemove
            String[] line = currentLine.split(" ");
            String fir = line[1];
            String las = line[2];
            for(int c = 0; c < players.size(); c++){
                if(players.get(c).getFirst().equals(fir) && players.get(c).getLast().equals(las) ){
                    System.out.println(fir + " " + las);
                    String text2 = currentLine.replaceAll("[.*?]", ".150");
                    writer.write(text2 + System.getProperty("line.separator"));
                }
            }
        }

"Some of the longer lines of text extend to be more than one line so the buffered views them as a new line." That's not a line. That's multiple lines. If you've got a line break (any of "\r\n", "\n" or "\r"), you've got a new line - if you want to define "line" to be anything else, don't use `BufferedReader.readLine` — Jon Skeet, Jun 14 '15 at 16:59
Right. I want the buffered reader to separate lines only when it reaches a ";" instead of a "\n". What is a better option would a scanner be able to do this more efficiently? — Waggoner_Keith, Jun 14 '15 at 17:01
Use a `Scanner` and set the delimiter to `";"`. I'm sure there are some tutorials for that "out there". — Tom, Jun 14 '15 at 17:03

score 11 · Accepted Answer · edited Jun 14 '15 at 17:10

11

It would be much easier to do with a Scanner, where you can just set the delimiter:

Scanner scan = new Scanner(new File("/path/to/file.txt"));
scan.useDelimiter(Pattern.compile(";"));
while (scan.hasNext()) {
    String logicalLine = scan.next();
    // rest of your logic
}

edited Jun 14 '15 at 17:10

Erick G. Hagstrom

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answered Jun 14 '15 at 17:05

Mureinik

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There will be additional new lines on the `logicalLine` - that might need some clensing – ring bearer Jun 14 '15 at 17:10
How about two characters as delimiter? one `empty space` and one `new line` @Mureinik – AmiNadimi Jul 05 '18 at 16:04
@AmiNadimi do you mean that that sequence is a delimiter, or either can be a delimiter? – Mureinik Jul 05 '18 at 16:08
second phrase @Mureinik :) – AmiNadimi Jul 05 '18 at 16:13
2

@AmiNadimi you can use a regex: `scan.useDelimiter(Pattern.compile("[ \n]"));` – Mureinik Jul 05 '18 at 16:58

score 3 · Answer 2 · answered Jun 14 '15 at 17:15

To answer your question directly, it is not possible. Buffered Reader cannot scan stream in advance to find this character and then return everything before target character.

When you read from stream with Buffered Reader you are consuming characters and you cannot really know character without reading.

You could use inherited method read() to read only single character and then stop when you detect desired character. Granted, this is not good thing to do because it contradicts the purpose of BufferedReader.

Thank you. Your right after it is much easier to use a scanner due to the face that the buffered reader cannot get a target character as easy. — Waggoner_Keith, Jun 14 '15 at 17:18

Buffered Reader read text until character

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