Java String Array without implicit size

hey people

I'm trying to get strings from a text inside a String array without implicit size

as if: cycle where method reads a line then stores into the array

op here.

let me describe what's going on and sorry for my english

there is a text file with several lines of text, and the number of lines is not known.
I need a way to grab the lines from the BufferedReader/FileReader and sort of store it - as in an array -, because later I will give this array to another class that will do a lot of things, like swap chars from chars, remove chars, etc...

but arrays need an implicit number to be created, and I don't know if later on I will be able to perform such swap/remove characters*...

ArrayList could be good, but can I do things* with the stored strings?

thank you and sorry for my english/nervousness? =/