How to update last line in a file.

Question

Hi
I need to append some text which should be at 2nd last line of a text file. I am getting the last line using RandomAccessFile and by ,
        fileHandler.seek(fileHandler.length()-1-lastLine.length()-1);
        fileHandler.writeUTF("last_line\r"+lastLine.replaceFirst("0x00", "0x80"));the above code i am trying to append the text with the updated last line. But instead of appending, the above code just replaces the last line.
How to solve this problem ?
BR
Umer

Answer 1

gimbal2 wrote:
Muhammad Umer wrote:
Hi
I need to append some text which should be at 2nd last line of a text file. I am getting the last line using RandomAccessFile and by ,
fileHandler.seek(fileHandler.length()-1-lastLine.length()-1);
fileHandler.writeUTF("last_line\r"+lastLine.replaceFirst("0x00", "0x80"));the above code i am trying to append the text with the updated last line. But instead of appending, the above code just replaces the last line.
How to solve this problem ?
BR
UmerRemember that a file, even a text file, is nothing more than a piece of administration: the administration of a collection of bytes to be exact. There are no lines, only bytes. Those bytes may represent something like a line, but that is basically only interesting during the presentation of data, the data itself has nothing to do with lines at all.
So what you are doing is seeking to a specific location on the harddrive and you are writing some bytes. Whatever was there is overwritten by the new data. You assumed that what would happen is what you see happen in a text editor, that data is inserted at the spot of the cursor, but I hope you realize that you cannot make those assumptions. Also, what you see happening is not what the text editor application is actually doing; the difference between presentation and business logic.Thank you for such a nice explanation. I have solved the problem
And for PrintWriter i will try it for understanding. Thank you.