In this post, we will see how to convert array to list in java.
There are may ways to convert array to list:
Table of Contents
- By using Arrays.asList[]:
- Using Collections.addAll[] method :
- Using Java 8s Stream
- Manual way using add[] method:
By using Arrays.asList[]:
This is an easy method to convert Array into list.We just need to pass array as parameter to asList[] method.It is a Static method available in Arrays class so, called it by class name Arrays.asList[].
Syntax:
1 2 3 | public static List asList[T x] |
It returns a fixed size List as of size of given array.Since returned List is fixed-size we cannot add more elements.If we do so it throws UnsupportedOperationException And T represent generics means any type of Array.
Example:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | package org.arpit.java2blog; //import all these package for conversion import java.util.List; import java.util.Arrays; import java.util.ArrayList; public class ConvertArrayToListAsListMain { public static void main[String arg[]] { //create and initialization of an array Integer[] arr={81,82,83,84,85}; //print content of Array System.out.println["Elements of Array are:"]; for [int a: arr] { System.out.println[a]; } //Convert array into list usingArrays.asList[] method List list=Arrays.asList[arr]; System.out.println["Elements of list are:"]; //print elements of list System.out.println[list]; } } |
OUTPUT:
Elements of Array are:
[81] [82] [83] [84] [85] Elements of list are: [81,82,83,84,85]
Using Collections.addAll[] method :
This method is available in Collections class.Remember that the array and List should be of same type.
Syntax:
public static boolean addAll[Collection c,T x]
Where c is a collection into which value is to be insert and x is an array contains values to be insert in c.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | package org.arpit.java2blog; //import all these package for conversion import java.util.List; import java.util.ArrayList; import java.util.Collections; public class ConvertArrayToListAsListMain { public static void main[String arg[]] { //creation of Integer array Integer[] arr={81,82,83,84,85}; //print content of Array System.out.println["Elements of Array are:"]; for [int a: arr] { System.out.println[a]; } //creation of List List list=new ArrayList[]; //assign all the element of array in list using Collection.addAll[] method Collections.addAll[list,arr]; System.out.println["Elements of list are:"]; //print elements of list System.out.println[list]; } } |
OUTPUT:
Elements of Array are:
[81] [82] [83] [84] [85] Elements of list are: [81,82,83,84,85]
Using Java 8s Stream
We can use Java 8s Stream to convert an array to List.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | package org.arpit.java2blog; //import all these package for conversion import java.util.List; import java.util.stream.Collectors; import java.util.Arrays; public class ConvertArrayToListAsListMain { public static void main[String arg[]] { //creation of Integer array int[] arr={1,3,5,6,10}; //print content of Array System.out.println["Elements of Array are:"]; for [int a: arr] { System.out.println[a]; } //Using Java 8 Stream List list=Arrays.stream[arr].boxed[].collect[Collectors.toList[]]; System.out.println["Elements of list are:"]; //print elements of list System.out.println[list]; } } |
OUTPUT:
1
3
5
6
10
Elements of list are: [1,3,5,6,10]
Manual way using add[] method:
We use add[] method inside loop to convert Array into List.
Example :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | package org.arpit.java2blog; import java.util.List; import java.util.ArrayList; public class ConvertArrayToListMain { public static void main[String arg[]] { //create and initialization of array int[] arr={81,82,83,84,85}; //print content ofArray using for each loop System.out.println["Elements of Array are:"]; for [int a: arr] { System.out.println[a]; } List list=new ArrayList[]; //conversion of array into list using add[] method for [int a: arr] { list.add[a]; } System.out.println["Elements of list are:"]; System.out.println[list]; } } |
OUTPUT:
[81] [82] [83] [84] [85] Elements of list are: [81,82,83,84,85]
Thats all about Converting the array to List in java.