Which is better design: writing a file or maintaining a list?

Question

Hi everybody,
I'm just looking for a quick recommendation from the design perspective. For a group of 20,000 strings or more, if they need to be edited, is it better for efficiency and speed to save them in a list within a program, or to write a file containing the strings, and then access them from there? If you have an opinion on that I would really appreciate it.
Thanks!
Jezzica85

Answer 1

jezzica85 wrote:
So, if I definitely don't need a separate file, and I may not need a list, is there an easy way to read multiple lines in the same file reader? The easiest way to read individual lines, from a java.io.FileReader, is to wrap it in a BufferedReader and use readLine().
Like this:BufferedReader in = new BufferedReader(myFileReader);
String line;
while((line = in.readLine() != null) {
  // do stuff with line
Basically, I need to determine which lines are in my final file both by knowing the line I'm reading and the lines before and after it.If you only can tell whether you need a line depending on the lines that come after it, then you're going to have to store the line while you read the subsequent lines. In that case, a list will be fine. (Well, you can also use a regular scalar String-typed variable, but chances are you're going to be storing multiple lines at a time, thus a List). If you're only going to make the determination based on lines that came earlier, then you don't need a list. You might want to use boolean or other types of variables to keep track of whether you need to keep a line.
For example, if the only criterion is that spans of blank lines get replaced by a single blank line, then you could probably get by with a single String variable. Stick the current line into a variable, then get the next line. If both the new line and the previous line are blank, throw away the new line. Otherwise, print the old one and put the new one in the old one's place in the variable.
It will all depend on your program requirements. Just try to keep things simple and don't build stuff than you need.