Thread: APpending a file with an Integer(Question Inside)

Hello,

I want to fiqure why this simple code dose not work. I want to append data to an existing file but it has to be a number not a String.

   File f = new File("C:\\Test\\kkk.txt");
  FileWriter wf = new FileWriter(f,true);
 BufferedWriter br = new BufferedWriter(wf);
 int x = 50;
br.write(x);
br.close();
    }
    }

I am still trying to learn so if it's a simple mistake I'm sorry. The following code writes a random number to a text file. I am making an educated guess that it's reading it as binary and in some shape form or fashion 50 equals 2 or something in binary. How do I get to just to write 50 at the end of the file. I know I can use the formatter class but that doesn't have a method for appending my data.

Note that you are using a FileWriter and a BufferedWriter, and thus anything written to this file with any type of Writer *must* be a String. Also the file is a text file, so you really have no choice -- you *must* write a String and only a String to this file. To not do so makes no sense at all.

Okay, I understand what you're saying. Is it at all possible,to convert my number to a string and insert it in the file. After that read it back in as a String and convert it as a integer, so then I can treat it as number. I have tried this using the scanner method and it throws me an exception. Please respond back.

Thanks

Yes, ints can be easily changed to String via the String.valueOf(...) method. And int Strings can be read in with a Scanner, if done properly, or as a String and then converted to int via Integer.parseInt(...).

This is what I got i tried but i still having trouble

    File f = new File("C:\\Test\\kkk.txt");
  FileWriter wf = new FileWriter(f,true);
  FileOutputStream fos = new FileOutputStream(f);
 DataOutputStream dos = new DataOutputStream(fos);
 dos.writeUTF(50);
Scanner sr = null;
sr = new Scanner(f);
String a = "";
while(sr.hasNext()){
a =   sr.next();
 
 
}
int b = Integer.parseInt(a);
System.out.print(a);
    }
    }

It throws a number format exception

What am I doing wrong here.

If it throws a NumberFormatException, then you're trying to parse something that's not a number into a number. Solution: don't do that. Only parse a number String.

Then I am confused on how to proceed. How can I store " dos.writeUTF(50);" and change it to a int?