Tutorial: Learn How To Convert An Array To An ArrayList In Java! 👍
In this guide, we’ll take a look at how to convert an array to an ArrayList in Java — we’ll investigate several examples where we turn an array into an ArrayList using pure Java and then we’ll cover several solutions when converting an array to an instance of java.util.ArrayList using one or more open-source libraries.
Array To ArrayList Java Tutorial TOC
We’ll also look at the performance of each solution as well, which is important as not all approaches are equal when it comes to speed.
This article is part of an introductory series on Java.
Software developers often find the need to convert arrays into List objects (ArrayList probably being one of the more popular classes) when dealing with objects in order to leverage the flexibility and utility of the List implementation for easier and more effective data manipulation.
Transforming arrays in Java into instances of java.util.List enables developers to access a more robust set of methods for managing data, including adding, removing, and traversing elements, methods which are unavailable when working with simple Java arrays.
Java arrays and ArrayLists, while serving similar purposes as containers for objects, differ significantly in their flexibility and functionality.
An array is a fixed-size data structure that does not permit dynamic resizing, while the ArrayList implementation, which is part of Java’s Collection Framework, provides dynamic resizing functionality and comes with a multitude of built-in methods to facilitate the manipulation of the ArrayList’s contents.
Java arrays can contain both primitive values as well as object references while implementations of the Java List can only hold references to objects.
Let’s take a look at several options for converting a Java array to an ArrayList next.
This article was updated on March 11th, 2025.
Example Zero: The Arrays.asList example array to List conversion code.
This tutorial explains how to use the Java Arrays.asList method in Java including its functionality, limitations, and use cases.
This guide demonstrates the Java Arrays asList method’s ability to convert arrays into fixed-size instances of java.util.List and highlights that the resulting List instance is immutable.
The walkthrough also includes step-by-step instructions with code examples, illustrating how developers can effectively use asList Java code in their applications.
Example One: Convert an array into a mutable instance of java.util.ArrayList using the Java ArrayList Constructor
The tutorial explains how to use the ArrayList constructor in Java to convert a Java array into an ArrayList.
This guide provides step-by-step instructions, demonstrating how to use the constructor that accepts a Collection, starting with an array and transforming it into a mutable ArrayList.
For developers seeking a practical Java ArrayList Constructor example, this tutorial provides a clear, hands-on approach.
Example Two: Review the Java Stream to ArrayList Example
The following instructional relies on a Java Stream to ArrayList style conversion abd provides a step-by-step guide regarding how to convert a Java array to an ArrayList using the Java Stream API.
This tutorial explains the process of creating a stream from an array, boxing primitive types, and collecting the result into an ArrayList.
The example demonstrates how to effectively transform and handle data structures, offering code examples and detailed explanations.
Example Three: Review The Guava Lists.newArrayList Example
This tutorial provides instructions regarding how to use Google Guava Lists class to convert arrays into ArrayList objects in Java.
This article demonstrates the use of the Lists newArraylist method, offering a step-by-step guide regarding how to use this method in Java or Groovy scripting.
We cover key aspects of the Lists.newArrayList method and include examples that should help readers explore this functionality.
Conclusion
This example Java code covered in this article is based on research from the StackOverflow post entitled How to convert int[] into List<Integer> in Java?.
