Write to an offset using DataOutputStream

Question

In my project, we are writing a file using DataOutputStream. We are writing different data types like short, byte, int and long and we are using respective methods in DataOutputStream like writeShort(), writeByte() etc.

Now, I want to edit one record in this file at a particular offset. I know the offset from which that record starts but I am not sure what is the right approach of writing to the file because only method in DataOutputStream supporting offset is the one which takes byte[].

I want to write the whole record which is a combination of different data types as mentioned above.

Can someone please tell me what is the correct approach for this?

Answer 1

In your case, you should use RandomAccessFile in order to read and/or write some content in a file at a given location thanks to its method seek(long pos).

For example:

try (RandomAccessFile raf = new RandomAccessFile(filePath, "rw")) {
    raf.seek(offset);
    // do something here
}

NB: The methods writeShort(), writeByte() etc. and their read counterparts are directly available from the class RandomAccessFile so using it alone is enough.