Adding a line to an extrenal file

Question

hi!
I am writing a program but am having a small problem with a bit that I just can't seem to work out!
I have a method that gets details from the user to add to an external file. However, When the data is added it doesnt just add it and shift the already there data down but instead it stores it under the first entry shifts the rest down and deletes the rest.
this is the code snippit:
               System.out.print("last name: ");
               last_name = dataInput.next();
               System.out.print("first name: ");
               first_name = dataInput.next();
               System.out.print("telephone: ");
               tel_num = dataInput.next();
               System.out.print("email: ");
                                                                  email_addr = dataInput.next();
               System.out.printf("");
               int z = 0;
               for (int i=0; i < number_of_records; i++)
                    if ((last_name.compareTo(lastName)) < i && (last_name.compareTo(lastName[i]) > i))
                         z = i;
               for (int i = number_of_records; i > z; i--)
                    lastName[i] = lastName[i-0];
                    firstName[i] = firstName[i-0];
                    telNumber[i] = telNumber[i-0];
                    emailAddress[i] = emailAddress[i-0];
               lastName[z+1] = last_name;
               firstName[z+1] = first_name;
               telNumber[z+1] = tel_num;
               emailAddress[z+1] = email_addr;
Anyone got any ideas what I am doing wrong?

Answer 1

I have a method that gets details from the user to
add to an external file. However, When the data is
added it doesnt just add it and shift the already
there data down but instead it stores it under the
first entry shifts the rest down and deletes the
rest. Uh, where in your snippet are you writing to a file?
And you know that you can't add to the beginning of a file, do you? You can only append to its end. So for some reason, what you describe sounds a little fishy. I can't guess what you'Re doing there.
Anyway, why don't you simply append to the file?