FileWriter

[kirba devi]

Hi
i am facing problem in appending characters to the existing file.
Also i need the difference between flush() and close().?
As i read one of the post and i have tried without using flush() characters are written to the file or bytestream . ?
how is that working?then what is the exact of flush method?

import java.io.*;

class TestFileWriter {

public static void main(String[] args) {

try{
char[] arr={'c','a','b','d','e','f'};
File f=new File("fg.txt");
FileWriter fw=new FileWriter(f);
fw.write('f');
fw.write(97);
fw.write("arath",1,3);
fw.write(arr,1,5);
System.out.println(fw.getEncoding());
FileWriter fw1=new FileWriter(f,true);
fw1.write("vana",1,3);
fw1.flush();
fw1.close();
fw.close();

}catch(IOException ioe){
ioe.printStackTrace();
}


}
output:faharabdef

what my expected output:faratabdefana

Regards
Kirba

[Ulf Dittmer]

You should always close a file before opening a second FileWriter (or similar) that uses it.

[kirba devi]

Hi Dittmer,
But still i am not getting the expected output.
Please correct me if i am wrong.
try{
char[] arr={'c','a','b','d','e','f'};
File f=new File("fg.txt");
FileWriter fw=new FileWriter(f);
fw.write('f');
fw.write(97);
fw.write("arath",1,3);
fw.write(arr,1,5);
fw.close();
System.out.println(fw.getEncoding());
FileWriter fw1=new FileWriter(f,true);// Line 1fw1.write("vana",1,3);
fw1.flush();
fw1.close();


}catch(IOException ioe){
ioe.printStackTrace();
}

See the bold statement ,what i am trying to do is appending some characters to the contents in the file

Regards
Kirba

[Ralph Jaus]

Sure you get it. Just remove the comment:

// Line 1 fw1.write("vana",1,3);

But the first version of your program is really very interesting. Hope I will going to understand what happens there.

[kirba devi]

Hi Ralph,
Even after removing i am getting the same output,and not the expected outptu.

Please help....

Regards
Kirba.

[kirba devi]

try{
char[] arr={'c','a','b','d','e','f'};
File f=new File("fg.txt");
FileWriter fw=new FileWriter(f);
fw.write('f');
fw.write(97);
fw.write("arath",1,3);
fw.write(arr,1,5);
fw.close();
System.out.println(fw.getEncoding());
FileWriter fw1=new FileWriter(f,true);// Line 1
fw1.write("vana",1,3);
fw1.flush();
fw1.close();


}catch(IOException ioe){
ioe.printStackTrace();
}


not getting my expected output:faratabdefana

[Ralph Jaus]

I tried your code and I'm getting "faratabdefana". What's your output ? By the way, the strings you are working with aren't very helpfull in such discussions. Something like fw.write("fw"), fw1.write("fw1") would be much more descriptive than fw.write("arath",1,3) or fw.write(arr,1,5).

[Sazzad Hossain]

Hi,
Just adding the line fw.flush() before opening the second FileWriter gave me the expected output.

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class FileWriterTest {

public static void main(String[] args) {

try{
char[] arr = {'c','a','b','d','e','f'};
File f = new File("C:\\_develop\\Test.txt");
FileWriter fw = new FileWriter(f);
fw.write('f');
fw.write(97);
fw.write("arath",1,3);
fw.write(arr,1,5);
fw.flush(); // Add this line
System.out.println(fw.getEncoding());
FileWriter fw1=new FileWriter(f,true);
fw1.write("vana",1,3);
fw1.flush();
fw1.close();
fw.close();
}
catch(IOException ioe)
{
ioe.printStackTrace();
}
}

}

Hope this help.

[Raphael Rabadan]

Hello,
when we use FileWriter it has a some kind of buffer so we don't use so much the I/O to get more performance. So, when we use .flush() we make sure to write the things we used on .write() commands on the file.

To say the truth i don't know how exactly the buffers works, but, to make sure, use the .flush() to write the things :-)

and guys, please use the CODE tag for codes.
here is a code that works how it should:

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
 
public class FileWriterTest {
public static void main(String[] args) {
try {
char[] arr = { 'c', 'a', 'b', 'd', 'e', 'f' };
File f = new File("fwTest.txt");
FileWriter fw1 = new FileWriter(f);
fw1.write('f');
fw1.write(97);
fw1.write("arath", 1, 3);
fw1.write(arr, 1, 5);
fw1.flush();
fw1.close();
System.out.println(fw1.getEncoding());
FileWriter fw2 = new FileWriter(f, true);
fw2.write("vana", 1, 3);
fw2.flush();
fw2.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}

Kind Regards,
Raphael Rabadan
[ July 22, 2008: Message edited by: Raphael Rabadan ]