CODEWITHSUNDEEP
javabytebufferfilechannel
jam
jam

Reputation: 1293

FileChannel - append byte buffer at eof?

I wondered if there is a possibility to add a byte buffer to the end of a file by using the file channel's position method.

I have read that it is neccessary to open the file output stream with the append flag

ByteBuffer byteBuffer = ...;
FileOutputStream fileOutputStream = new FileOutputStream("path/to/file", true);
FileChannel channel = fileOutputStream.getChannel();

channel.write(bytebuffer);
channel.force(true);
channel.close();

but shouldn't it be possible to append the buffer by modifiing the position of the channel.

"The size of the file increases when bytes are written beyond its current size"

ByteBuffer byteBuffer = ...;
FileOutputStream fileOutputStream = new FileOutputStream("path/to/file");
FileChannel channel = fileOutputStream.getChannel();

channel.position(channel.size()).write(bytebuffer);
channel.force(true);

I would be grateful for some explanations since the file gets overwritten.

Upvotes: 0

Views: 1570

Answers (1)

user207421
user207421

Reputation: 310957

The file gets overwritten in the second example because you didn't specify an append parameter with value true. After that, positioning it at EOF just positions it at zero.

Upvotes: 2

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