How to convert Array to List in Java

Gaurav BhardwajMay 13th, 2020Last Updated: May 11th, 2020

1 110 2 minutes read

Hello Friends,

In this tutorial, we will learn, various ways in which we can convert an array to a List.

package com.blogspot.javasolutionsguide;

import com.google.common.collect.Lists;
import org.apache.commons.collections4.CollectionUtils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class ArrayToList {

    public static void main(String[] args) {

        //Before Java 8
        System.out.println("Before JAVA 8........................................");

        // 1.
        String[] names = new String[] {"Gaurav", "Sachin", "Yuvraj"};
        List<String> nameList =  Arrays.asList(names);
        System.out.println("using Arrays.asList: " + nameList);

        //2
        List<Integer> list = Arrays.asList(1, 2, 3);
        System.out.println("Inline primitive array to Integer List using Arrays.asList(): "
                + list);

        //Java 8
        System.out.println("JAVA 8 ................................................");
        // 3. primitive array
        int intArray[] = {1, 2, 3};
        List<Integer> integerList1 = Arrays.stream(intArray).boxed()
                                                         .collect(Collectors.toList());
        System.out.println("Primitive int array to Integer List using Array.stream(): "
                + integerList1);

        // 4. primitive array with IntStream
        List<Integer> integerList2 = IntStream.of(intArray).boxed()
                                                          .collect(Collectors.toList());
        System.out.println("Primitive int array to Integer List using IntStream.of(): "
                + integerList2);

        // 5. Object type array to Integer List
        Integer integerArray[] = {1, 2, 3};
        List<Integer> integerList3 = Arrays.stream(integerArray)
                                                           .collect(Collectors.toList());
        System.out.println("Object type array to Integer List using Arrays.stream:  "
                + integerList3);

        // 6. Integer Array to ArrayList
        ArrayList<Integer> arrayList = Arrays.stream(integerArray)
                .collect(Collectors.toCollection(ArrayList::new));
        System.out.println("Integer type array to Integer ArrayList using Arrays.stream:  "
                + arrayList);

        // 7. Integer Array to LinkedList
        LinkedList<Integer> linkedList = Stream.of(integerArray)
                                           .collect(Collectors.toCollection(LinkedList::new));
        System.out.println("Integer type array to Integer LinkedList using Arrays.stream:  "
                + linkedList);

        // 8. Integer Array to Immutable List
        List<Integer> immutableList = Collections.unmodifiableList(Arrays.asList(integerArray));
        System.out.println("Integer type array to Immutable List using Arrays.stream:  "
                + immutableList);

        //9. JAVA 9
        System.out.println("JAVA 9.........................................................");
        String[] playerNames = {"Sachin", "Dhoni", "Yuvraj"};
        List<String> players = List.of(playerNames);
        System.out.println("Array to List using Java 9 List.of() :" + players);

        //10. JAVA 10
        System.out.println("JAVA 10.........................................................");
        List<Integer> integerList = List.copyOf(Arrays.asList(integerArray));
        System.out.println("Array to List using Java 10 List.copyOf() :" + integerList);

        //11. Apache Commons
        System.out.println("Apache Commons...................................................");
        List<Integer> targetList = new ArrayList<>(6);
        CollectionUtils.addAll(targetList, integerArray);
        System.out.println("Array to List using Apache Common CollectionUtils.addAll() :"
                + integerList);

        //12 Google Guava
        System.out.println("Google Guava......................................................");
        Integer[] sourceArray = {1, 2, 3};
        List<Integer> targetList1 = Lists.newArrayList(sourceArray);
        System.out.println("Array to List using Google Guava Lists.newArrayList:"
                + integerList);
    }
}

External Dependency Used :

<dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-collections4</artifactId
      <version>4.4</version>
 </dependency>
 <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
      <version>3.10</version>
 </dependency>
 <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
      <version>16.0.1</version>
 </dependency>

All the code for this tutorial can be found in GitHub. So in this tutorial we learnt various ways in which we can convert array to List in java.That is all for this tutorial.Please subscribe the blog for more such tutorial.

Published on Java Code Geeks with permission by Gaurav Bhardwaj, partner at our JCG program. See the original article here: How to convert Array to List in Java

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