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Abhinav Kanoria
7,730 PointsConverting array of Strings to an ArrayList<String>
Consider the following lines of code: String[] languages = {"English", "French", "Thai", "Spanish", "Korean", "Chinese"}; List<String> langList = new ArrayList<String>(); langList = Arrays.asList(languages);
If I execute the command langList.get(3) to get the language at position 3, I get Spanish as expected. But when I want to add another language to the langList ArrayList, i.e., when I do
langList.add("Hindi"); I get an 'UnsupportedErrorException'. SO why can't I add more languages to langList?? I cannot remove exixting languages(like French, Korean) from langList as well. Please help. Thanks!
2 Answers
Seth Kroger
56,414 PointsBecause Arrays.asList() is fixed size, what you want to do is copy that list in into a new ArrayList. You can accomplish this with:
List<String> langList = new ArrayList<String>(Arrays.asList(languages));
Andre Luis Araujo Santos
3,241 PointsWell, having a look in this the oracle documentation:
https://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html#asList(T...)
This method returns a fixed-size List, which means that we can't change its size (add or remove elements). It's like a regular array with its specified size, but with the List methods (except the methods add/remove, I suppose).
Abhinav Kanoria
7,730 PointsThanks a lot. That helped!
Abhinav Kanoria
7,730 PointsAbhinav Kanoria
7,730 PointsHi Seth! Thanks a lot. This one worked for me. I can now add and remove languages from my langList. But can you explain why you passed Arrays.asList(languages) as a parameter? How is doing this different from doing List<String> langList = new ArrayList<String>(); langList = Arrays.asList(languages);