List and Array transfer

1. List to array

Using the t[] List.toarray (t[] a) method in the API, cannot be used directly (t[]) List.toarray ()

Because arrays cannot be cast directly, for example

        Object[] objs={"123", "456"};        String[] Strings=(string[]) Objs;        System.out.println (Arrays.tostring (strings));

        list<string> list=New arraylist<>();        List.add ("abc");        List.add ("deg");        String[] Strings=(string[]) List.toarray ();        System.out.println (Arrays.tostring (strings));

This will cause classcastexception,

So it is not possible to use this method directly, ToArray (new t[size])must be used; The size here can be any number

        list<string> list=New arraylist<>();        List.add ("abc");        List.add ("deg");        List.add ("Teg");        string[] Strings  = (string[]) List.toarray (new string[1]);        System.out.println (Arrays.tostring (strings));

2. Array Goto List

Call the Aslist method of arrays.
Aslist
public static <T> list<t> aslist (T ... a) returns a list of fixed sizes supported by the specified array. (Changes to the returned list are "written straight" to the array.) This approach, together with Collection.toarray, serves as a bridge between an array-based API and an Collection-based API. The returned list is serializable and implements the randomaccess.
This method also provides a convenient way to create a fixed-length list that is initialized to contain multiple elements:

List stooges = arrays.aslist ("Larry", "Moe", "Curly");
Parameters:
A-an array of supported lists.
Return:
Specifies the list view of the array.
See also:
Collection.toarray ()

        string[] strings={"Hello", "World"};        List<String> list=arrays.aslist (strings);        System.out.println (List.tostring ());

[Hello, World]

　　

List and Array transfer