Write String to a text file

Question

I have this code that gets GPS data from input stream make the test file but there is nothing inside. Can you please tell me what is the problem in here?

public void run ()
        {
            byte[] buffer = new byte[1024];
            int len = -1;
            try
            {
                while ( ( len = this.in.read(buffer)) > -1 )
                {
                    String gpsInfo = new String(buffer,0,len);
                    PrintWriter data = new PrintWriter("test.txt");
                    data.println(gpsInfo);
                    System.out.print(gpsInfo);
                }
            }
            catch ( IOException e )
            {
                e.printStackTrace();
            }            
        }

I am getting the right console output.

still no luck on the output file. Do I need to append? Does the method overwrite the file every time? — Mix Austria, Oct 06 '15 at 03:39

score 2 · Accepted Answer · answered Oct 06 '15 at 03:39

You are opening the same file repeatedly in the while loop. You should open before going into the loop. Also flush() and close() the stream.

      PrintWriter data = new PrintWriter("test.txt");
      while((len = this.in.read(buffer)) > -1) {
        String gpsInfo = new String(buffer,0,len);
        data.println(gpsInfo);
        System.out.print(gpsInfo);
      }
      data.flush();
      data.close();

If you are using java 7 and above then you can open the file in try block itself. It will be closed automatically once your code in the try block completes. But don't forget to flush() the data.

  public void run () {
    byte[] buffer = new byte[1024];
    int len = -1;
    try (PrintWriter data = new PrintWriter("test.txt")) {
      while((len = this.in.read(buffer)) > -1) {
        String gpsInfo = new String(buffer,0,len);
        data.println(gpsInfo);
        System.out.print(gpsInfo);
      }
      data.flush();
    }
    catch ( IOException e ) {
      e.printStackTrace();
    }
  }

@MixAustria It is writing the output into file. I would suggest you to provide the absolute path of the file, for testing purpose. — YoungHobbit, Oct 06 '15 at 03:55

score 0 · Answer 2 · edited May 23 '17 at 12:06

0

The way you doing is actually correct. Once the data is written into a text file, close the PrintWriter instance.

data.close();

If you want to know about more information check this link

Code Snippet:

PrintWriter data = new PrintWriter("test.txt");
String gpsInfo = null;

while ( ( len = this.in.read(buffer)) > -1 )
{
     gpsInfo = new String(buffer,0,len);
     data.println(gpsInfo);
     System.out.print(gpsInfo);
}

data.close();

edited May 23 '17 at 12:06

Community

1
1

answered Oct 06 '15 at 03:28

Vignesh Shiv

1,129
7
22

still no output on the text file. – Mix Austria Oct 06 '15 at 03:37
tried the updated code but still no output on the text file. – Mix Austria Oct 06 '15 at 03:52
It works for me. `Provide the absolute path of the file` and try. – Vignesh Shiv Oct 06 '15 at 04:13

Write String to a text file

2 Answers2