Java – How to convert a primitive Array to List

Java – How to convert a primitive Array to List
Code snippets to convert a primitive array int[] to a List<Integer> :

int[] number = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

List<Integer> list = new ArrayList<>();
for (int i : number) {
list.add(i);
}

In Java 8, you can use the Stream APIs to do the boxing and conversion like this :

List<Integer> list = Arrays.stream(number).boxed().collect(Collectors.toList());
1. Classic Example
Full example to convert a primitive Array to a List.

ArrayExample1.java
package com.mkyong.array;

import java.util.ArrayList;
import java.util.List;

public class ArrayExample1 {

public static void main(String[] args) {

int[] number = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

List<Integer> list = convertIntArrayToList(number);
System.out.println("list : " + list);

}

private static List<Integer> convertIntArrayToList(int[] input) {

List<Integer> list = new ArrayList<>();
for (int i : input) {
list.add(i);
}
return list;

}
}

Output

list : [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Note
You can’t use the popular Arrays.asList to convert it directly, because boxing issue.
int[] number = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
// No, the return type is not what we want
List<int[]> ints = Arrays.asList(number);

2. Java 8 Stream
Full Java 8 stream example to convert a primitive Array to a List.

ArrayExample2.java
package com.mkyong.array;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class ArrayExample2 {

public static void main(String[] args) {

int[] number = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

// IntStream.of or Arrays.stream, same output
//List<Integer> list = IntStream.of(number).boxed().collect(Collectors.toList());

List<Integer> list = Arrays.stream(number).boxed().collect(Collectors.toList());
System.out.println("list : " + list);

}
}

Output

list : [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

from:http://www.mkyong.com/java/java-how-to-convert-a-primitive-array-to-list/