I read and write strings using RandomAccessFile and strings in
my file are just as follow:
string1/n
string2/n
...
stringn/n
For example, when I read string2 from file and the length of string2 is 4. Now I add or remove something to the string and the length become more or less, then I save it. But when I read it
from file again, I find it's changed.
string1/n
string21/n
string22/n
...
stringn/n