I'm editing List of ValueProxies and I'm trying to implement reordering of
items (move to front, move to back, move up, move down the list). Since
ListEditors work by reflecting change in underlying List and List interface
does not support atomic "move" operation for item reordering, my only
option is to first remove item from List and then add elements at desired
index. So far so good, but in ListEditor, underlying List contains
*unflushed* values so when I reinsert them, newely created editors get old
values and I loose changes made before reordering took place.
Since flushing ListEditor before remove/add didn't seem as a good idea
(breaks editor contract and I would have to propagate Driver down the
editors hierarchy) I've ended up cloning ListEditor and its underlying
ListEditorWrapper to my own DynamicListEditor and DynamicListEditorWrapper
(couldn't even extend them, because relevant members are private).
In DynamicListEditorWrapper I've added one additional method to reorder
both elements in underlying list and their corresponding editors in-place:
public void move(int fromIndex, int toIndex) {
workingCopy.add(toIndex, workingCopy.remove(fromIndex));
editors.add(toIndex, editors.remove(fromIndex));
for (int i = Math.min(fromIndex, toIndex), j = Math.max(fromIndex,
toIndex); i <= j; i++)
editorSource.setIndex(editors.get(i), i);
}
In DynamicListEditor I've used that new wrapper and exposed it in getList
method:
public DynamicListEditorWrapper<T, E> getList() {
return list;
}
Now I'm able to move item one place up the list by calling:
int currIndex = /* get current index, easy */;
if (currIndex == 0)
return;
listEditor.getList().move(currIndex, currIndex - 1);
I works, but I can't shake off the feeling that I'm over-engineering it and
that there is a better (simpler) way for doing this. After all, Lists are
ordered collections and editing that order should not be this complicated.
Any advice?
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