How can I convert String[] to ArrayList<String>

Question

Possible Duplicate:
Assigning an array to an ArrayList in Java

I need to convert a String[] to an ArrayList<String> and I don't know how

File dir = new File(Environment.getExternalStorageDirectory() + "/dir/");
String[] filesOrig = dir.list();

Basically I would like to transform filesOrig into an ArrayList.

Solution 1

You can do the following:

String [] strings = new String [] {"1", "2" };
List<String> stringList = new ArrayList<String>(Arrays.asList(strings)); //new ArrayList is only needed if you absolutely need an ArrayList

Solution 2

Like this :

String[] words = {"000", "aaa", "bbb", "ccc", "ddd"};
List<String> wordList = new ArrayList<String>(Arrays.asList(words));

or

List myList = new ArrayList();
String[] words = {"000", "aaa", "bbb", "ccc", "ddd"};
Collections.addAll(myList, words);

Solution 3

List<String> list = Arrays.asList(array);

The list returned will be backed by the array, it acts like a bridge, so it will be fixed-size.

Solution 4

List myList = new ArrayList();
Collections.addAll(myList, filesOrig); 

Solution 5

You can loop all of the array and add into ArrayList:

ArrayList<String> files = new ArrayList<String>(filesOrig.length);
for(String file: filesOrig) {
    files.add(file);
}

Or use Arrays.asList(T... a) to do as the comment posted.

View more solutions

Comments

[zapl]

...new ArrayList<String>(filesOrig.length); prevents that the backing array has to be grown in size. Potentially faster.

[Alexandre Hitchcox]

Thanks, this is the one I used

[MysticMagicϡ]

Thanks.. I couldn't use Arrays.asList as I had to add element to list later. addAll worked perfectly :)

[Bob Lissner]

I don't believe that you can then make changes to this list. stringList.remove(1) sure isn't working for me.

[suriv]

This answer is wrong and won't even compile.

[Jack]

@suriv: the only problem was List instead of ArrayList but the answer is not wrong. Creating a copy of an array to an ArrayList is not always necessary, sometimes you just need to view an array as a list. Mind that creating a real copy, as in new ArrayList<>(Arrays.asList(array)) requires a memory for each element of the list. For example a 100000 Object array requires 800kb of RAM just for the pointers to references.

[suriv]

For the benefit of future readers, trying to add or remove elements from this List will throw an exception.

[Jack]

@suriv: it's clearly stated in the answer and it's clearly stated in the documentation, in any case thanks for the clarification.

[Someone Somewhere]

second option works