A few things first:
The name
lines is misleading.
readLine() only reads one line from the input so I would rename that variable to
line instead.
Instead of this:
ArrayList<String> arrayList = new ArrayList<String>();
Do something like this:
List<String> cleanedUpLines = new ArrayList<String>();
Starting with
Java 7 you can write:
List<String> cleanedUpLines = new ArrayList<>();
A name like
cleanedUpLines or something like this is better than
arrayList. As Tony said in his response, try to think more about your variable names.
When appropriate, the declared type should be the interface or abstract type (List), not the implementation type (ArrayList).
The variable
end is never changed inside the
while-loop so you'll never exit normally; you'll exit with an IOException from
br.readLine(). I'm assuming you didn't include that so we could focus on your main logic instead.
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Now to your logic:
isFound and
tagFound are redundant. They don't really serve a purpose because if you remove them and the if-statements leaving only what's inside the if-statements, the code will work the same way.
Thinking of states and transitions will help you with this kind of logic. The main state that you have is cleaning up lines: you either are or you aren't. The program will always be reading lines from the input, regardless of the "cleaning up" state.
This is how I would do it: Prepare a cleanedUpLines list and another list for uncleaned lines. Start at "not cleaning up" state. Read a line from input. Does this line have text that signals I have to start cleaning up lines? If yes, switch to "cleaning up" state. If in "cleaning up" state, add the line to unclean lines, otherwise, add line to cleanedUpLines. If in "cleaning up" state and the line has text that signals I should stop cleaning up, then clean up all the lines in the unclean lines list, then add the results to the cleanedUpLines list, then clear out the unclean lines list to get ready for the next time we switch to the "cleaning up" state; switch to "not cleaning up" state. Repeat from reading a line from input while you have more lines to read.
I'll leave it to you to try this out with code and arrange the control flow statements appropriately. This is just off the top of my head, mind you, but I think I've covered most of the necessary logic. You would probably be better off by separating the logic to "clean up all the lines in the unclean lines list" into a separate method.
