Java – how to allow users to drag and drop releases in vaadin tables?

I have a multi - row table with custom components I want to allow users to delay the release

I tried the following code, but I couldn't drag any lines:

tblStructure = new Table();
tblStructure.setSizeFull();
tblStructure.setSelectable(false);
tblStructure.setSortEnabled(false);
tblStructure.setDragMode(Table.TableDragMode.ROW);
tblStructure.setNullSelectionAllowed(true);
tblStructure.setDropHandler(new DropHandler() {

        /**
         * 
         */
        private static final long serialVersionUID = 1L;

        @Override
        public AcceptCriterion getAcceptCriterion() {
            return AcceptAll.get();
        }

        @Override
        public void drop(DragAndDropEvent event) {
        }
    });

Solution

I know I'm responding to an old thread I find it very troublesome in vaadin I refuse to use treetable or other components to achieve this result I want to share my solution with anyone who searches this content because I can't find a simple and clear answer myself I also want to do something for the community because we use a lot of open source software

Create a class, such as sortabletable, which extends the regular vaadin table

public class SortableTable extends Table {
    private static final long serialVersionUID = 1L;

    public SortableTable() {
        setDragMode(TableDragMode.ROW);
        setSelectable(true);
        setDropHandler(new DropHandler() {
            private static final long serialVersionUID = 1L;

            @Override
            public AcceptCriterion getAcceptCriterion() {
                return AcceptAll.get();
            }

            @Override
            public void drop(DragAndDropEvent event) {
                Transferable t = event.getTransferable();
                Object sourceItemId = t.getData("itemId");

                AbstractSelectTargetDetails dropData = (AbstractSelectTargetDetails)event.getTargetDetails();
                Object targetItemId = dropData.getItemIdOver();

                switch(dropData.getDropLocation()) {
                case BOTTOM:
                    moveAfter(targetItemId,sourceItemId);
                    break;
                case MIDDLE:
                case TOP:
                    final Object prevItemId = prevItemId(targetItemId);
                    moveAfter(prevItemId,sourceItemId);
                    break;
                }
            }
        });
    }
...

Next, create this custom function to move table items

@SuppressWarnings("unchecked")
    /**
     * 
     * @param targetItemId
     * @param sourceItemId
     * @return ItemId of the object the item moved to
     */
    public Object moveAfter(Object targetItemId,Object sourceItemId) {
        if(sourceItemId == null)
            return null;
        Item sourceItem = getItem(sourceItemId);

        Object[] propertyIds = getContainerPropertyIds().toArray();
        int size = propertyIds.length;
        Object[][] properties = new Object[size][2];

        // backup source item properties and values
        for(int i = 0; i < size; i++) {
            Object propertyId = propertyIds[i];
            Object value = sourceItem.getItemProperty(propertyId).getValue();
            properties[i][0] = propertyId;
            properties[i][1] = value;
        }
        removeItem(sourceItemId);
        Item item = addItemAfter(targetItemId,sourceItemId);

        // restore source item properties and values
        for(int i = 0; i < size; i++) {
            Object propertyId = properties[i][0];
            Object value = properties[i][1];
            item.getItemProperty(propertyId).setValue(value);
        }

        return sourceItemId;
    }


}

Let's try to explain For some obvious reason, when removeitem is called, the table item is completely deleted and deleted from the table You cannot put the same object back into a table except to copy its properties and values to a new row This is exactly what the custom moveafter does Another part of the code is inspired by the "tree to table drag - 'n-drop" example in the vaadin sampler mentioned by Nebraska in his previous post

I hope I can help others with this article to greet!

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