How do I read from a certain line until a certain line?

Question

For example I want to read a text file from line number 20056 until line 1159450 and outputs it into the output window but I do not know how to do so as the method line.readline() starts with the first line.

This is my code:

String line;
int currentLineNo = 1;
int startLine = 20056;//40930;
int endLine = 1159450;

FileReader file = new FileReader("yourfilepath");
BufferedReader reader = new BufferedReader(file);

PrintWriter writer = new PrintWriter("yourfilepath", "UTF-8");

while (currentLineNo < startLine) {
    currentLineNo++;
}

while(currentLineNo >= startLine && currentLineNo <= endLine) {
    // System.out.println(currentLineNo);
    line = reader.readLine();

    System.out.println(line);
    // writer.println(line);
    currentLineNo++;
}

reader.close();
writer.close();

How do I print only from line 20056 until line 1159450 and outputs it into the output window?

In your first `while` loop, you're not advancing your `reader`. If you call `reader.readLine()` inside the loop, it will use up a line each iteration. — khelwood, Oct 24 '16 at 18:33
Possible duplicate of [How to read a specific line using the specific line number from a file in Java?](http://stackoverflow.com/questions/2312756/how-to-read-a-specific-line-using-the-specific-line-number-from-a-file-in-java) — MordechayS, Oct 24 '16 at 18:33
Similar question here: http://stackoverflow.com/questions/14217997/java-how-to-use-bufferedreader-to-read-specific-line — Jay Hamilton, Oct 24 '16 at 18:36
how do i associate the readLine with the currentLineNo @khelwood ? — Nik Mohamad Lokman, Oct 24 '16 at 18:40
How do I not read the first few lines I do not want ? @khelwood — Nik Mohamad Lokman, Oct 24 '16 at 18:50
Yes I have been referring to many question but none of it works T_T @JayHamilton — Nik Mohamad Lokman, Oct 24 '16 at 18:51

Jay Hamilton · Answer 1 · 2016-12-09T20:18:27.490

1

String line;
int currentLineNo = 1;
int startLine = 20056;//40930;
int endLine = 1159450;

FileReader file = new FileReader("yourfilepath");
BufferedReader reader = new BufferedReader(file);

PrintWriter writer = new PrintWriter("yourfilepath", "UTF-8");

while (currentLineNo <= endLine)
{
    line = reader.readLine();
    if(currentLineNo >= startLine && currentLineNo<=endLine) 
    {  System.out.println(line); }

    currentLineNo++;
}

reader.close();
writer.close();

edited Dec 09 '16 at 20:18

answered Oct 24 '16 at 18:39

Jay Hamilton

36
6

It still prints the first line :/ I need it to print only from line 20056 until line 1159450 – Nik Mohamad Lokman Oct 24 '16 at 18:43
try jays code with your first while loop commented out. – spanglerb Oct 24 '16 at 18:49
It worked ! I just need to delete the first while loop thank you very much jay ! Have a nice day :D – Nik Mohamad Lokman Oct 24 '16 at 18:56
Worked. Thank you spanglerb :D – Nik Mohamad Lokman Oct 24 '16 at 18:57
Thank Jay he did the heavy lifting :-) I hear accepting answers is a good thank you present. – spanglerb Oct 24 '16 at 18:59
Edited the question with the answer and credited to Jay :) – Nik Mohamad Lokman Oct 24 '16 at 19:04
I did but it says vote less than 15 are recorded but will not be displayed Jay :/ – Nik Mohamad Lokman Oct 24 '16 at 19:53
@NikMohamadLokman: you are probably trying to upvote. Instead, click on the tick mark to the left, so that it turns green. This is what we mean by "accepting an answer". Thanks. – halfer Oct 26 '16 at 12:05

score 0 · Accepted Answer · answered Oct 26 '16 at 12:03

(Posted solution on behalf of the OP).

I just need to remove the first while loop.

String line;
    int currentLineNo = 1;
    int startLine = 20056;//40930;
    int endLine = 1159450;

    FileReader file = new FileReader("yourfilepath");
    BufferedReader reader = new BufferedReader(file);

    PrintWriter writer = new PrintWriter("yourfilepath", "UTF-8");

    while(currentLineNo<=endLine) 
    {
        line = reader.readLine();
        if(currentLineNo >= startLine && currentLineNo<=endLine) 
        {  System.out.println(line); }

        currentLineNo++;
    }

    reader.close();
    writer.close();

Credit to Jay Hamilton.

How do I read from a certain line until a certain line?

2 Answers2