Array and collection system conversion

Array to a set of <list Arrays are inside a static internal class that has not been achieved add, remove Method>

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

Array to a collection

String[] arr = new String[]{"hello","world"};
List<String> list = new ArrayList<String>(Arrays.asList(arr));

Turn an array of collections

String[] array=list.toArray(new String[list.size()]);

Problems encountered

1. The importance of generics 1

int[] arr = new int[]{1,2,3,4,5};
List list = Arrays.asList(arr);
System.out.println(list.size());　

2. array to a given set of add java.lang.UnsupportedOperationException

Integer[] arr = new Integer[]{1,2,3,4,5};
List<Integer> list = Arrays.asList(arr);
list.add(6);
System.out.println(list.size());