ArrayList Constructor

Question

public ArrayList(Collection<? extends E> c) {
       elementData = c.toArray();
       size = elementData.length;

       if (elementData.getClass() != Object[].class)
             elementData = Arrays.copyOf(elementData, size, Object[].class);
}

I did not understand that "if (elementData.getClass() != Object[].class)" statement and why it is required. This is the implementation for ArrayList constructor. Can someone please explain. Thanks!

khelwood · Accepted Answer · 2015-10-30 19:52:03Z

6

Collection.toArray() might return an Object array, or it might return some other array type that has been cast to an Object array. The code you quote is making sure that its data array is actually an Object array, so it is able to receive any Object.

answered Oct 30, 2015 at 19:52

khelwood

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