I have an ArrayList that I want to output completely as a String. Essentially I want to output it in order using the toString of each element separated by tabs. Is there any fast way to do this? You could loop through it (or remove each element) and concatenate it to a String but I think this will be very slow.
If you were looking for a quick one-liner, as of Java 5 you can do this:
myList.toString().replaceAll("\\[|\\]", "").replaceAll(", ","\t")
Additionally, if your purpose is just to print out the contents and are less concerned about the "\t", you can simply do this:
myList.toString()
which returns a string like
[str1, str2, str3]
If you have an Array (not ArrayList) then you can accomplish the same like this:
Arrays.toString(myList).replaceAll("\\[|\\]", "").replaceAll(", ","\t")
This is quite an old conversation by now and apache commons are now using a StringBuilder internally: http://commons.apache.org/lang/api/src-html/org/apache/commons/lang/StringUtils.html#line.3045
This will as we know improve performance, but if performance is critical then the method used might be somewhat inefficient. Whereas the interface is flexible and will allow for consistent behaviour across different Collection types it is somewhat inefficient for Lists, which is the type of Collection in the original question.
I base this in that we are incurring some overhead which we would avoid by simply iterating through the elements in a traditional for loop. Instead there are some additional things happening behind the scenes checking for concurrent modifications, method calls etc. The enhanced for loop will on the other hand result in the same overhead since the iterator is used on the Iterable object (the List).