Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Can we convert an array to list and back in Java?
The List provides two methods to convert a List into Array.
1. Use toArray() method without parameter.
Object[] toArray()
Returns
An array containing all of the elements in this list in proper sequence.
2. Use toArray() with array.
<T> T[] toArray(T[] a)
Type Parameter
T − The runtime type of the array.
Parameters
a − The array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
Returns
An array containing the elements of this list.
Throws
ArrayStoreException − If the runtime type of the specified array is not a supertype of the runtime type of every element in this list.
NullPointerException − If the specified array is null.
In order to convert an array to list we can use Arrays.asList() method to get the list containing all the elements of an array.
public static <T> List<T> asList(T... a)
Type Parameter
T − The runtime type of the element.
Parameters
a − The array by which the list will be backed.
Returns
A list view of the specified array.
Example
Following is the example showing the usage of toArray() and Arrays.asList() methods −
package com.tutorialspoint;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class CollectionsDemo {
public static void main(String[] args) {
Integer[] array = {1, 2, 3, 4, 5};
// array to List conversion
List<Integer> list = new ArrayList<>(Arrays.asList(array));
System.out.println("List: " + list);
// list to array conversion
Object[] items = list.toArray();
for (Object object : items) {
System.out.print(object + " ");
}
System.out.println();
// list to array conversion
Integer[] numbers = list.toArray(new Integer[0]);
for (int number : numbers) {
System.out.print(number + " ");
}
}
}Output
This will produce the following result −
List: [1, 2, 3, 4, 5] 1 2 3 4 5 1 2 3 4 5
144 Views
To Continue Learning Please Login