java printwriter: Output file empty

Question

Question: How do you ask the defined output class to print result in the output file as .txt

All other java classes seem to be working and runs alright but it fails to print out any data in the output folder. I have imported the PrintWriter, but it will not create the file

Code:

import java.io.IOException;
 import java.io.PrintWriter;



public class Outputs
{
    //INSTANCE FIELDS

    private Solution cwsSolution;
    private Solution bestSol;

    // CLASS CONSTRUCTOR

    Outputs()
    {   cwsSolution = null;
        bestSol = null;
    }

    // SET METHODS

    public void setCWSSol(Solution cwsSol)
    {   cwsSolution = cwsSol;
    }

    public void setOBSol(Solution obSol)
    {   bestSol = obSol;
    }

    // GET METHODS

    public Solution getCWSSol()
    {   return cwsSolution;
    }

    public Solution getOBSol()
    {   return bestSol;
    }

    //PUBLIC METHOD 
printOutputFile()

    public void sendToFile(String outFile)
    {
        try 
        {   PrintWriter out = new PrintWriter(outFile);
            out.println("***************************************************");
            out.println("*                      OUTPUTS                    *");
            out.println("***************************************************");
            out.println("\r\n");
            out.println("--------------------------------------------");
            out.println("Clarke & Wright Solution (parallel version)");
            out.println("--------------------------------------------");
            out.println(cwsSolution.toString() + "\r\n");
            out.println("--------------------------------------------");
            out.println("\r\n OUR BEST SOLUTION:\r\n");
            out.println("--------------------------------------------");
            out.println(bestSol.toString() + "\r\n");
            out.close();
        } catch (IOException exception) 
        {   System.out.println("Error processing output file: " + exception);
        }
    }
}

Are you really calling sendToFile() method from anywhere? I don't see any? — Kartic, May 06 '15 at 12:59
As Kartic mentions please show how you call sendToFile() and where? — Sybren, May 06 '15 at 13:00
Hi Champagne, i don't get any exception or i am not seeing any at the moment. I will create a sendto method now and see how this works. — Hassana abdallah, May 06 '15 at 13:19

score 0 · Accepted Answer · edited May 23 '17 at 12:30

i created a dummy program using the sendToFile() and it is working fine and creating an output file.

Please paste the error that you are getting. I hope you are initializing the variables "cwsSolution" and "cwsSolution" correctly and no null is being thrown.

Please see if following link helps: How to use PrintWriter and File classes in Java?

Sample code is below:

   public class Outputs
 {
    String bestSol="bestSol";
    String cwsSolution="cwsSolution";

   public void sendToFile(String outFile)
   {

   try 
   {   PrintWriter out = new PrintWriter(outFile);
       out.println("***************************************************");
       out.println("*                      OUTPUTS                    *");
       out.println("***************************************************");
       out.println("\r\n");
       out.println("--------------------------------------------");
       out.println("Clarke & Wright Solution (parallel version)");
       out.println("--------------------------------------------");
       out.println(cwsSolution.toString() + "\r\n");
       out.println("--------------------------------------------");
       out.println("\r\n OUR BEST SOLUTION:\r\n");
       out.println("--------------------------------------------");
       out.println(bestSol.toString() + "\r\n");
       out.close();
   } catch (IOException exception) 
   {   System.out.println("Error processing output file: " + exception);
   }
 }

   public static void main(String[] args) {
        Outputs output = new Outputs();
        output.sendToFile("C:\\t.txt");
   }
}

i see the problem now. i shall create a sendtofile now. Many Thanks — Hassana abdallah, May 06 '15 at 13:21

score -1 · Answer 2 · answered May 06 '15 at 12:55

-1

The problem that I see is that you have forgotten to .flush() the PrintWriter to definately send the data to the output target before closing it.

[...]
out.println(bestSol.toString() + "\r\n");
out.flush();
out.close();
[...]

answered May 06 '15 at 12:55

Matthias Brück

194
1
2
12

2

calling close will absolutely flush the buffer, so adding a flush call won't help in this case – ControlAltDel May 06 '15 at 12:57
Well, I remember occasions where stuff I wrote didn't get saved with `close` only. – Matthias Brück May 06 '15 at 13:05

java printwriter: Output file empty

2 Answers2