I have an ArrayList, and I want to remove repeated strings from it. How can I do this?
If you don't want duplicates in a Collection, you should consider why you're using a Collection that allows duplicates. The easiest way to remove repeated elements is to add the contents to a Set (which will not allow duplicates) and then add the Set back to the ArrayList:
Set set = new HashSet<>(yourList);
yourList.clear();
yourList.addAll(set);
Of course, this destroys the ordering of the elements in the ArrayList.