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.
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
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);
Arrays.asList as I had to add element to list later. addAll worked perfectly :)
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.
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.List myList = new ArrayList();
Collections.addAll(myList, filesOrig);
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.
...new ArrayList<String>(filesOrig.length); prevents that the backing array has to be grown in size. Potentially faster.You can do something like
MyClass[] arr = myList.toArray(new MyClass[myList.size()]);
