How To Convert A Primitive Array To List In Java

Posted By : Sanjay Saini | 26-Jan-2018

Hi guys,

In this blog.I will be going to explain to you how to convert a primitive data type array to List. we are taking a primitive array of int for explaining the ways.

Before Java 8, It was compulsory to iterate over array to convert into the List but In Java 8 we are easily doing this and didn't need looping over array.

Sample Code to change a primitive array int[] to a List.

First, start with how we were to this Before Java 8 :

package com.sanjay;

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

public class ConverPrimitiveArrayToList {

	public static void main(String[] args) {

		 int[] intArray = {10,11,12,13,14,15,16,17,18,19,20};

	     List<Integer> integerArrayList = convertPrimitiveArrayToList(intArray);
	        System.out.println("Array List : " + integerArrayList);

	    }

	private static List convertPrimitiveArrayToList(int[] intArray) {

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

	    }
	}
	

Now we will discuss how to do this In java 8 :

Java 8 has introduced a new feature i.e Streams API and with the help of Streams API, we can do many things easily. Code Sample of Java 8 :

package com.sanjay;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;


public class ConverPrimitiveArrayToList {

	public static void main(String[] args) {

		 int[] intArray = {10,11,12,13,14,15,16,17,18,19,20};

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

}

Note : You can’t use the most popular Arrays.asList to convert it directly, because boxing issue.

 

About Author

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Sanjay Saini

Sanjay has been working on web application development using frameworks like Java, groovy and grails. He loves listening to music , playing games and going out with friends in free time.

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