Go How to convert an array to ArrayList in Java

Method Summary:

Element[] Array = {new Element (1), new Element (2), new Element (3)}; arraylist<element> ArrayList = new Arraylist<element> (arrays.aslist (array));  Method 1list<element> list = arrays.aslist (array);  Method 2list<element> list = new arraylist<element> (array.length); Method 3collections.addall (list, array);

Method 1, annotations

ArrayList the construction method of the document.
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);}

Method 2, annotations

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.

such as: list.add( newElement(4));

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

PS: Original address: http://www.cnblogs.com/liushaobo/p/4423102.html

Go How to convert an array to ArrayList in Java