How do you use tags?
At the bottom of each of my posts it explains how to use code tags. Although I see you have used them in your latest post.

You basically have 2 choices:

1. Read in one line at a time and perform whatever operation you need to do before reading the next line.
2. Read in each line and store it in something like an ArrayList. Then once you have all the lines, perform whatever operations you need to do.

If you read the API docs for readLine() it tells you it will return the next line in the stream or null if the end of the stream has been reached. So you need to repeatedly read in a line until you get a null return value. Assuming you need to store the lines you could do something like this:
Code:
List<String> myList = new ArrayList<String>();

String myLine = in.readLine();
while ( myLine != null ) {
    myList.add(myLine);
    myLine = in.readLine();
}