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Thread: Reading Lines

  1. #1
    gkoef is offline Member
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    Default Reading Lines

    Is there a way to make a program read text from a file one line at a time and manipulating that line before reading the next line?

    An example would be, taking the line from the file and adding it to another file.

  2. #2
    ozzyman's Avatar
    ozzyman is offline Senior Member
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    Read about Scanner:
    Scanning (The Java™ Tutorials > Essential Classes > Basic I/O)
    Scanner (Java 2 Platform SE 5.0)

    then use

    Scanner.nextLine() to take one line at a time,

    after each call of 'nextLine()' use your own methods to process the data before the loop comes back around to 'nextLine()' again.

  3. #3
    subith86 is offline Senior Member
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    In addition to ozzyman's suggestion you can try BufferedReader also as shown below
    Java Code:
    		File myFile = new File("D://premdas/Desktop/file_tutorials/parseme.txt");
    
    		try {
    			FileReader fr = new FileReader(myFile);
    			BufferedReader br = new BufferedReader(fr);
    			String line;
    			while((line = br.readLine()) != null)
    				System.out.println(line);
    				[I][COLOR="Green"]//do your manipulation here for each line[/COLOR][/I]
    		} catch (FileNotFoundException e) {
    			e.printStackTrace();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}

  4. #4
    droidus is offline Senior Member
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    is one better than the other? which one is more common? i have heard about the burreredreader, but have never used it.

  5. #5
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    sunde887 is offline Moderator
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    I like to use a scanner when getting input from command line, and buffered reader for reading files. I am not sure which is better(I believe, for files the buffered reader is better).

    I think the i/o tutorials go over which to prefer.

  6. #6
    JosAH's Avatar
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    Quote Originally Posted by droidus View Post
    is one better than the other? which one is more common? i have heard about the burreredreader, but have never used it.
    Nor a Scanner, nor a BufferedReader care where their input comes from (see their constructors (*)). I believe that both classes have to do some buffering which doesn't harm normally. I prefer a BufferedReader if all I have to do is read lines (the other Readers are just too stupid to do it ;-)

    kind regards,

    Jos

    (*) for convenience a Scanner can also directy take a File as its constructor parameter, but both can take Readers as their constructor parameters which is nice (imho)
    The only person who got everything done by Friday was Robinson Crusoe.

  7. #7
    gkoef is offline Member
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    Default Thankyou

    Thankyou everyone for helping me with this problem. I am more aware of BufferedReader so that is what I will use.

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