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Thread: Print Writer Problem

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    Default Print Writer Problem

    I need help on figuring out how to send data to a file without it replacing the data and also repeating other data. The code below doesnt replace any darta, but it repeats data that i want in there (which i dont want replacing):

     public void writeCustomerData()
     
        {
            try{
            Frame owner = null; //Sets the owner of the file to null.
            FileDialog newFileDialog1 = new FileDialog(owner, "Open", FileDialog.SAVE); //Creates a fileDialog object.
            newFileDialog1.setVisible(true); //Chooses the file that will be read in.
            File newFile1 = new File(newFileDialog1.getFile());
     
            if(customerMap.size()> 0)
            {
     
              for(Customer customers : customerMap.values())
                {
                 PrintWriter nw = new PrintWriter(new FileWriter(newFile1,true)); 
                 nw.print("ok");
                  customers.writeData(nw);
                  nw.close();
                }
            }
            else
            {
                System.out.println("No Customers In The List");
            }
        }
        catch(FileNotFoundException a)
        {
            System.out.print("File cannot be found");
        }
        catch(IOException a)
        {
            System.out.print("File cannot be found");
        }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Print Writer Problem

    To keep from writing data to a file that is already in the file, the code will have to read the file, examine the data and select what data should be written out to the file and replace what is currently in the file with the new version of the data.

    Please edit your post and wrap your code with code tags:
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Print Writer Problem

    well the data i want is in a map , but i need to have that in a loop to get them all , but have other data not repeat where it says ok i need that only once!

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    Default Re: Print Writer Problem

    If you don't want some data to be in the file, the code will need to determine what data should not be written to the file.

    How can the program look at all the data that could be written to the file and select the data that should be written to the file and write it and not write the data it does not want written to the file?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Print Writer Problem

    i need one piece of data to write once , followed by all data in a hashmap with out no replacing of the data beause all the data append each other

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    Default Re: Print Writer Problem

    Can you use a Set to hold the data and keep the data from being repeated?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Print Writer Problem

    it has to be a hash map cz i will have to be able to get them later via the key. is there a way of doing it the way i want . n its not the map thats repeating its the other information.

  8. #8
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    Default Re: Print Writer Problem

    What is the "other information" that is repeating? How is it related to what is in the disk file?

    If you want unique data values written to the file, put the data in a Set before writing it to the file. That will remove duplicates.
    If you don't understand my answer, don't ignore it, ask a question.

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