CODEWITHSUNDEEP
javafilewriter
Adrian Jandl
Adrian Jandl

Reputation: 3015

Using two FileWriters where one appends and the other doesn't

I am using two FileWriters after each other.

The first one does not append

BufferedWriter versionWriter = new BufferedWriter(new FileWriter(new File(filePath)));
versionWriter.write(s);
versionWriter.close();

whereas I would like the one after to append.

BufferedWriter bw = new BufferedWriter(new FileWriter(new File(filePath), true));
bw.newLine();
bw.write(s);

The problem is that my first FileWriter destroys the whole file, therefore making me lose my data.

The reason I am doing using two FileWriters is that the first one is supposed to overwrite the first line of my textfile, whereas the second one is supposed to append to the end of the file.

What is the correct way to do this?

Edit: I realise it is possible to first read everything and then save it back, but this is highly inefficient, especially since I will need to store a lot of data in the file.

Upvotes: 0

Views: 63

Answers (1)

Jan Goyvaerts
Jan Goyvaerts

Reputation: 3033

Use RandomAccessFile.seek(...) to write data into a file at a specific position.

But there's no magic to "replace the first line of file" apart from reading into memory, replace the first line and writing out to file again. Unless that line always has the very same length. And you take care not to overwrite the EOL character. :-)

Btw, don't forget to call flush() before closing.

Upvotes: 2

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