Drag View and Drop it on RecyclerView item Android

问题

I am developing an android application that has a screen contains the following:

1. Recycler view that contains categories as the below figure
2. Separate view at the botton and the user should able to drag it on a RecyclerView item, and after drop the user will show changing at the RecyclerView item data (for example items count at the category)

I need some help about how to implement this process to drag View into Recycler item, the following figure explains exactly what I want to do but have no idea how to do it

any help is much appreciated

回答1:

Start by adding a draglistener to your inflated view in onCreateViewHolder of your recycler adapter.

view.setOnDragListener(new OnDragListener() {
    @Override
    public boolean onDrag(View view, DragEvent dragEvent) {

        switch (dragEvent.getAction()) {
            case DragEvent.ACTION_DRAG_STARTED:
                // drag has started, return true to tell that you're listening to the drag
                return true;

            case DragEvent.ACTION_DROP:
                // the dragged item was dropped into this view
                Category a = items.get(getAdapterPosition());
                a.setText("dropped");
                notifyItemChanged(getAdapterPosition());
                return true;
            case DragEvent.ACTION_DRAG_ENDED:
                // the drag has ended
                return false;
        }
        return false;
    }
});

In the ACTION_DROP case you can either change the model and call notifyItemChanged(), or modify directly the view (that won't handle the rebinding case). Also in onCreateViewHolder add a longClickListener to your View, and in onLongClick start the drag:

ClipData.Item item = new ClipData.Item((CharSequence) view.getTag());
String[] mimeTypes = {ClipDescription.MIMETYPE_TEXT_PLAIN};
ClipData dragData = new ClipData(view.getTag().toString(),
            mimeTypes, item);
view.setVisibility(View.GONE);
DragShadowBuilder myShadow = new DragShadowBuilder(view);

if (VERSION.SDK_INT >= VERSION_CODES.N) {
    view.startDragAndDrop(dragData, myShadow, null, 0);
} else {
    view.startDrag(dragData, myShadow, null, 0);
}

For more information about drag and drop check out the android developers site

来源：https://stackoverflow.com/questions/42066261/drag-view-and-drop-it-on-recyclerview-item-android