Arrays asList() method in Java with Examples
The asList() method of java.util.Arrays class is used to return a fixed-size list backed by the specified array. This method acts as a bridge between array-based and collection-based APIs, in combination with Collection.toArray(). The returned list is serializable and implements RandomAccess.
Tip: This runs in O(1) time.
public static List asList(T... a)
Parameters: This method takes the array a which is required to be converted into a List. Here … is known as varargs which is an array of parameters and works similar to an object array parameter.
Special Note: The type of array must be a Wrapper Class(Integer,Float, etc) in case of primitive data types(int, float,etc) , i.e you can’t pass int a but you can pass Integer a. If you pass int a, this function will return a List <int a> and not List <Integer> , as “autoboxing” doesn’t happen in this case and int a is itself identified as an object and a List of int array is returned, instead of list of integers , which will give error in various Collection functions .
Return Value: This method returns a list view of the specified array.
The list is: [A, B, C, D]
The list is: [10, 20, 30, 40]