code: private void ensureCapacity() {
  		if (size < selectionKeys.length) {
  			return;
  		}
  		SelectionKey[] newArray = new SelectionKey[selectionKeys.length * 2];
  		System.arraycopy(selectionKeys, 0, newArray, 0, size);
  		selectionKeys = newArray;
  	}
docs: Multiply the size of array twice