You can use the following instruction:
new ArrayList<>(Arrays.asList(array));
W3Schools
w3schools.com › java › java_arraylist.asp
Java ArrayList
Java Examples Java Videos Java Compiler Java Exercises Java Quiz Java Code Challenges Java Server Java Syllabus Java Study Plan Java Interview Q&A Java Certificate ... An ArrayList is like a resizable array. It is part of the java.util package and implements the List interface. The difference between a built-in array and an ArrayList in Java, is that the size of an array cannot be modified (if you want to ...
Top answer 1 of 16
5154
You can use the following instruction:
new ArrayList<>(Arrays.asList(array));
2 of 16
1014
Given:
Element[] array = new Element[] { new Element(1), new Element(2), new Element(3) };
The simplest answer is to do:
List<Element> list = Arrays.asList(array);
This will work fine. But some caveats:
- The list returned from asList has fixed size. So, if you want to be able to add or remove elements from the returned list in your code, you'll need to wrap it in a new
ArrayList. Otherwise you'll get anUnsupportedOperationException. - The list returned from
asList()is backed by the original array. If you modify the original array, the list will be modified as well. This may be surprising.
Videos
Java: Convert Array to ArrayList, and ArrayList to Array
Convert an Array to an ArrayList (Java Tutorial)
How to convert Array to ArrayList and ArrayList to Array (Core ...
03:14
how to convert array to arraylist in java - YouTube
02:59
How to convert arraylist to array in java | List to array conversion ...
09:40
Learn Java arraylists in 9 minutes! 📃 - YouTube
GeeksforGeeks
geeksforgeeks.org › java › conversion-of-array-to-arraylist-in-java
Conversion of Array To ArrayList in Java - GeeksforGeeks
July 23, 2025 - Exception in thread "main" java.lang.UnsupportedOperationException at java.util.AbstractList.add(AbstractList.java:148) at java.util.AbstractList.add(AbstractList.java:108) at GFG.main(File.java:16) It is therefore recommended to create new ArrayList and pass Arrays.asList(array reference) as an argument to it (i.e. as an constructor argument of ArrayList). Consider the following example:
GeeksforGeeks
geeksforgeeks.org › java › array-to-arraylist-conversion-in-java
Array to ArrayList Conversion in Java - GeeksforGeeks
July 11, 2025 - From Java 9, we can use the List.of() method to create an immutable list from an array. This method is simple and clean but note that the resulting list is immutable, so you cannot modify it. ... Parameters: The method accepts a mandatory parameter ‘a’ which is the array to be converted and T signifies the list’s element type(this can be omitted).
Sentry
sentry.io › sentry answers › java › create arraylist from array in java
Create ArrayList from array in Java | Sentry
The easiest way to convert to an ArrayList is to use the built-in method in the Java Arrays library: Arrays.asList(array).
TutorialsPoint
tutorialspoint.com › conversion-of-array-to-arraylist-in-java
Conversion of Array To ArrayList in Java
Using Arrays.asList() method - Pass the required array to this method and get a List object and pass it as a parameter to the constructor of the ArrayList class. Collections.addAll() method - Create a new list before using this method and then add array elements using this method to existing list.
Blogger
javarevisited.blogspot.com › 2011 › 06 › converting-array-to-arraylist-in-java.html
3 Ways to Convert an Array to ArrayList in Java? Example
Just now we were looking at converting array to arraylist and now we need to back to the former one. Anyway it’s simpler than you have probably thought again we have java.util.Arrays class as our rescue. This class acts as bridge between ArrayList to array. In this example of ArrayList to array we will convert our assetTradingList into String array.
Reddit
reddit.com › r/javahelp › converting arrays to arraylist
r/javahelp on Reddit: Converting Arrays to Arraylist
April 26, 2022 -
I want to convert an array to Array list, but the below code is throwing error
package Practice**;
**import java.util.ArrayList**;
**import java.util.Arrays**;
**import java.util.List**;
**public class test {
public static void main(String[] args) {
int[] nums = {1,2,34,4};
int ele = 5;
int target=0;
List<Integer> ans =Arrays.asList(nums);
}
}
Error: ava: incompatible types: inference variable T has incompatible bounds
equality constraints: java.lang.Integer
lower bounds: int[]
The code is working when I use wrapper claass Integer instead of int. ie Integer[] = {1,2,34,4}. But I don't understand why. Why do we have to use the wrapper class instead of primitive. Is there any alternate solution?
Thanks for help in advance!!
Top answer 1 of 5
5
In this case, Arrays.asList() produces a list of arrays, i.e., List. A normal iterative approach is best to populate the list. It may also be possible to do this with Streams, if you can use those.
2 of 5
4
With Stream it would be something similar to this: int[] array = {1,2,3,4,5}; List list = IntStream.of(array).boxed().collect(Collectors.toList());
BeginnersBook
beginnersbook.com › 2013 › 12 › how-to-convert-array-to-arraylist-in-java
How to convert an array to ArrayList in java
In the following example, since ... public class JavaExample { public static void main(String[] args) { //ArrayList declaration ArrayList<String> arrayList= new ArrayList<String>(); //Initializing Array String array[] = {"Text1","Text2","Text3","Text4"}; /* array.length returns ...
W3Schools
w3schools.com › java › ref_arraylist_toarray.asp
Java ArrayList toArray() Method
If the array in the argument is large enough to contain all of the list items then this method will return the argument itself after writing the list items into it. ... T refers to the data type of items in the list. ... import java.util.ArrayList; public class Main { public static void main(String[] args) { ArrayList<String> cars = new ArrayList<String>(); cars.add("Volvo"); cars.add("BMW"); cars.add("Ford"); cars.add("Mazda"); String[] carsArray = new String[4]; carsArray = cars.toArray(carsArray); for(String item : carsArray) { System.out.println(item); } } }
CodeAhoy
codeahoy.com › java › How-To-Convery-ArrayList-To-Array
ArrayList to Array Conversion in Java | CodeAhoy
March 1, 2020 - ... package com.codeahoy.ex; import ... elements to the list list.add(5); list.add(10); list.add(15); // Convert ArrayList to Array Integer[] array = list.toArray(new Integer[0]); // Print the array for (Integer n : array) { System.out.println(n); } } }...
Reddit
reddit.com › r/learnjava › what is the best way to convert an array to an arraylist?
r/learnjava on Reddit: What is the best way to convert an array to an arraylist?
February 18, 2019 -
For example, how would this:
input[j] = input[i];
be written using an arraylist? I've tried using input.indexOf(j) = input.indexOf(i); but I am given an unexpected type error.
CodeGym
codegym.cc › java blog › java collections › arraylist to array conversion in java
How to Convert an Array to ArrayList in Java
January 15, 2025 - ArrayList<Integer> boltsInventory = new ArrayList<Integer>(): Collections.addAll(boltsInventory, bolts); This will pass the entire contents of the Array bolts to the new ArrayList.
Programiz
programiz.com › java-programming › examples › convert-list-array
Java Program to Convert a List to Array and Vice Versa
import java.util.Arrays; import ...tln("Array: " + Arrays.toString(array)); // convert array to list List · languages= new ArrayList<>(Arrays.asList(array)); System.out.println("List: " + languages); } } ... In the above example, we have created an array of String ...
Scaler
scaler.com › home › topics › array to arraylist java
Array to ArrayList java - Scaler Topics
October 9, 2022 - This method is considered the most popular and used approach to convert an array into an ArrayList. The List.of() method in Java is used to create immutable lists.
Reddit
reddit.com › r/javahelp › list vs array vs arraylist
r/javahelp on Reddit: List vs Array vs ArrayList
September 12, 2023 -
Coming from Python, this whole Java thing is incredibly confusing. The thing is, they don't seem to mix and uses different methods such as .size() vs .length(). All of them also seem to be doing the same thing: having a group of something.
I really need a comparison of the three, and how to declare, manipulate, and access, etc them.
Top answer 1 of 5
16
These are three different things: Array - a very basic data structure. It has a fixed, predetermined size that must be known at the time of creating (instantiating) the array. Think of it as a sorting box with several slots. Here, you have .length - without parentheses as it is a property, not a method List - an interface (not a class) that defines certain behavior. It cannot be instantiated on its own. ArrayList - a concrete class that implements the List interface. When you see a declaration like List data = new ArrayList<>(); there are several things going on: Listprogramming against the interface - here, the interface List is used as data type - this is good practice as it allows you to at any time change the internal representation of the List - e.g. from ArrayList to LinkedList if you figure out that the other better suits your needs. this is a data type identifier. It limits the type of elements that can be stored in the list. Here, only String objects are allowed. If you were to omit this, the list would store Object (the ancestor of all Java classes) and descendant instances (i.e. Object and any subclass of it). data - just the variable name new - the keyword to create a new Object Instance ArrayList<>() - the constructor call. Here, the constructor without parameters of the ArrayList class is called. The diamond operator <> is used to infer (take) the data type for the ArrayList from the variable type (here String). So, the whole is: we create a new variable of type List that can only accept String elements and ist internally represented as ArrayList.
2 of 5
4
Array An array is a data structure built into the Java language which can hold a number of elements, all of the same type. It cannot be resized once it has been created, and you cannot add elements to it without specifying an index. // creates an array of 10 ints int[] arr = new int[10]; // sets the value of the 0th element to 5 arr[0] = 5; // prints the value of the 0th element, which is 5 System.out.println(arr[0]); // Sets e to the value of the 0th element of arr, which is 5 int e = arr[0]; // Sets the value of the 1st element to 6 arr[1] = 6; // prints the length of arr System.out.println(arr.length); // even though arr[9] has not been set, // all elements initialize to 0 when first created System.out.println(arr[9]); /* Illegal operations! */ // an exception is thrown since arr can only hold 10 elements System.out.println(arr[11]); // there is no shorthand syntax to get the last element of an array System.out.println(arr[-1]); // length is a variable, not a method System.out.println(arr.length()); // arr can only hold ints arr[2] = "Hello"; List A List is an class that is part of the Java Standard Library which allows for dynamic insertion and deletion of elements. You can't just create a List though, you have to use one of its subclasses, which includes ArrayList, and you have to use generics as well. Think of an ArrayList as a dynamic version of an array, and is the closest thing to Python's list datatype. // Make sure to import these at the top of your class! import java.util.List; import java.util.ArrayList; // creates an ArrayList of ints List myList = new ArrayList<>(); // adds 5 to myList myList.add(5); // prints the 0th element of myList, which is 5 System.out.println(myList.get(0)); myList.add(6); // removes the last element of myList, which is 6 int removed = myList.remove(); // prints the size of the list, which is 1 System.out.println(myList.size()); /* Illegal operations! */ // myList only has 1 element System.out.println(list.get(5)); myList.remove(); // removes 5 // throws an exception since the list is empty myList.remove(); // throws an exception since myList can only take ints myList.add("Hello"); // you can only use bracket notation on arrays System.out.println(myList[0]); // size is a method, not a variable System.out.println(myList.size); Other Info There are lots of other List subclasses you can use depending on the kind of operations you want to do on it, such as Queues, LinkedLists, and PriorityQueues. The reason why we use Integer instead of int when working with Lists is a limitation of the Java language. Generic types can only be object types, but primitive types, such as int, double, boolean, etc., are not object types, and thus we have to use autoboxing to work with primitives in this manner.
Codecademy
codecademy.com › learn › learn-java › modules › learn-java-arrays-and-arraylists › cheatsheet
Learn Java: Arrays and ArrayLists Cheatsheet | Codecademy
In Java, an array is used to store a list of elements of the same datatype. Arrays are fixed in size and their elements are ordered. ... Using the {} notation, by adding each element all at once. Using the new keyword, and assigning each position of the array individually. ... To change an element value, select the element via its index and use the assignment operator to set a new value. ... An ArrayList can easily be modified using built in methods.
DigitalOcean
digitalocean.com › community › tutorials › java-array-of-arraylist-of-array
Java Array of ArrayList, ArrayList of Array | DigitalOcean
August 4, 2022 - Below is a simple example showing ... args) { // List of String arrays List<String[]> list = new ArrayList<String[]>(); String[] arr1 = { "a", "b", "c" }; String[] arr2 = { "1", "2", "3", "4" }; list.add(arr1); list.add(arr2); // printing list of String arrays in the ArrayList ...
Codecademy
codecademy.com › docs › java › arraylist › .toarray()
Java | ArrayList | .toArray() | Codecademy
January 5, 2024 - Beginner Friendly.Beginner Friendly17 ... conversion. In the example below, the .toArray() method is used to convert an ArrayList named fruitsList containing strings to an array of strings....