The Java array and list are converted to each other

1. The array is converted into a list

The array can be converted to a list using the method: Arrays.aslist, together to understand

System.out.println (Arrays.aslist (new string[] {"A", "B"});

Print: [A, b]

list<integer> asList2 = arrays.aslist (new integer[] {1, 2}); System.out.println (ASLIST2);

Printed: [1, 2]

The following results are not expected

Print: [[[Email protected]]

If you are going to convert a primitive type array to a list of the corresponding package type, use Apache Commons Lang Bar, perhaps your project is using it, similar to the following using Arrayutils.toobject:

list<integer> list = Arrays.aslist (Arrayutils.toobject (new int[] {1, 2})); SYSTEM.OUT.PRINTLN (list);

Printed: [1, 2]

Note When you use the tool class Arrays.aslist () to turn an array into a collection, you cannot use its associated method to modify the collection, and its Add/remove/clear method throws a Java.lang.UnsupportedOperationException exception. The return object of Aslist is a arrays inner class, and there is no method to implement the collection, the data in the background is still an array, and the modification of the arrays affects the collection:

string[] countries = {"China", "Russia", "American"}; list<string> AsList3 = arrays.aslist (countries); countries[2] = "France"; System.out.println (ASLIST3);

Printed: [China, Russia, France]

2.List to Group

The list toarray (t[] Array) method, passing in an array of exactly the same type, the size of the array list.size ().

list<string> fruits = new arraylist<string> () Fruits.add ("Apple"); Fruits.add ("Pear"); Fruits.add (" Orange "); string[] Array = Fruits.toarray (new String[fruits.size ()));

　　

The Java array and list are converted to each other