How do I convert an array to ArrayList in Java?

Translate from: How to Convert arrays to ArrayList in Java?

This article analyzes the answer to one of the hottest questions on stack overflow, where the questioner gets a lot of prestige points, allowing him to get the right to do a lot of things on the stack overflow. It has nothing to do with me, let's take a look at it first.
The question is "How do I convert an array to ArrayList in Java?"

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

1. The most popular answer is also accepted by the most people

The most commonly accepted answer is the following:

ArrayList<Element> arrayList = new ArrayList<Element>(Arrays.asList(array));

First, let's look at the documentation for ArrayList's construction method.
ArrayList (Collection <? extends E > C): Constructs a list of elements that contain a specific container, and is returned according to the order of the container iterators.
So the construction method does the following things:
1. Converting container C to an array
2. Copy the array into an array called "Elementdata" in ArrayList
The source code for the ArrayList construction method is as follows:

public ArrayList(Collection<? extends E> c) {       elementData = c.toArray();       size = elementData.length;       if (elementData.getClass() != Object[].class)             elementData = Arrays.copyOf(elementData, size, Object[].class);}

2. Another popular answer

Another popular answer is:

List<ElementArrays.asList(array);

This is not the best because the size of the list returned by Aslist () is fixed. In fact, the returned list is not a java.util.ArrayList, but a private static class defined in java.util.Arrays . We know that the implementation of ArrayList is essentially an array, whereas the list returned by Aslist () is a fixed-size list supported by the original array. In this case, if you add or remove elements from the list, the program throws an exception unsupportedoperationexception.

list.add(new Element(4));

in"main" java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList    at collection.ConvertArray.main(ConvertArray.java:22)

3. Another solution

This solution is provided by Otto

array = {new Element(1new Element(2)};Listlistnew ArrayList<element>(array.length);Collections.addAll(listarray);

4. The issue of the indication of something

The problem is not difficult, but it is very interesting. Every Java programmer knows ArrayList, but it's easy to make such a mistake. I think this is the reason why the problem is very hot. If it's a similar problem for a particular domain of Java libraries, it's far less fiery.

There are many answers to this question that provide the same solution, as is the case with other problems with StackOverflow. I guess when people want to answer a question, they don't care what they say.

Reference: links to issues on StackOverflow

Translate from: How to Convert arrays to ArrayList in Java?

How do I convert an array to ArrayList in Java?