Create ArrayList from array

Question

I have an array that is initialized like:

Element[] array = {new Element(1), new Element(2), new Element(3)};

I would like to convert this

Answer 1

Another Java8 solution (I may have missed the answer among the large set. If so, my apologies). This creates an ArrayList (as opposed to a List) i.e. one can delete elements

package package org.something.util;

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

public class Junk {

    static <T> ArrayList<T>  arrToArrayList(T[] arr){
        return Arrays.asList(arr)
            .stream()
            .collect(Collectors.toCollection(ArrayList::new));
    }

    public static void main(String[] args) {
        String[] sArr = new String[]{"Hello", "cruel", "world"};
        List<String> ret = arrToArrayList(sArr);
        // Verify one can remove an item and print list to verify so
        ret.remove(1);
        ret.stream()
            .forEach(System.out::println);
    }
}

Output is...
Hello
world

Answer 2

We can easily convert an array to ArrayList. We use Collection interface's addAll() method for the purpose of copying content from one list to another.

 Arraylist arr = new Arraylist();
 arr.addAll(Arrays.asList(asset));

Answer 3

as all said this will do so

 new ArrayList<>(Arrays.asList("1","2","3","4"));

and the common newest way to create array is observableArrays

ObservableList: A list that allows listeners to track changes when they occur.

for Java SE you can try

FXCollections.observableArrayList(new Element(1), new Element(2), new Element(3));

that is according to Oracle Docs

observableArrayList() Creates a new empty observable list that is backed by an arraylist. observableArrayList(E... items) Creates a new observable array list with items added to it.

Update Java 9

also in Java 9 it's a little bit easy:

List<String> list = List.of("element 1", "element 2", "element 3");

Answer 4

1. If we see the definition of Arrays.asList() method you will get something like this:

    public static <T> List<T> asList(T... a) //varargs are of T type. 
   

   So, you might initialize arraylist like this:

    List<Element> arraylist = Arrays.asList(new Element(1), new Element(2), new Element(3));
   

   Note : each new Element(int args) will be treated as Individual Object and can be passed as a var-args.

2. There might be another answer for this question too.
   If you see declaration for java.util.Collections.addAll() method you will get something like this:

   public static <T> boolean addAll(Collection<? super T> c, T... a);
   

   So, this code is also useful to do so

   Collections.addAll(arraylist, array);
   

Answer 5

Given Object Array:

Element[] array = {new Element(1), new Element(2), new Element(3) , new Element(2)};

Convert Array to List:

    List<Element> list = Arrays.stream(array).collect(Collectors.toList());

Convert Array to ArrayList

    ArrayList<Element> arrayList = Arrays.stream(array)
                                       .collect(Collectors.toCollection(ArrayList::new));

Convert Array to LinkedList

    LinkedList<Element> linkedList = Arrays.stream(array)
                     .collect(Collectors.toCollection(LinkedList::new));

Print List:

    list.forEach(element -> {
        System.out.println(element.i);
    });

OUTPUT

1

2

3

Answer 6

Another update, almost ending year 2014, you can do it with Java 8 too:

ArrayList<Element> arrayList = Stream.of(myArray).collect(Collectors.toCollection(ArrayList::new));

A few characters would be saved, if this could be just a List

List<Element> list = Stream.of(myArray).collect(Collectors.toList());