android - ItemTouchHelper.SimpleCallback onMove() 未被触发

Question

我想在我的RecyclerView中实现拖放。正如我发现的那样，实现这一点的最佳方法是将 ItemTouchHelper 附加到 RecyclerView。

onSwiped() 工作正常，但永远不会触发 onMove()。

这是我的做法:

EditIngredientsRecyclerViewAdapter premixableIngredientsAdapter = new EditIngredientsRecyclerViewAdapter(this, typeOfComponents);
        GridLayoutManager gridLayoutManager1 = new GridLayoutManager(getContext(), 1);
        recyclerView.setAdapter(premixableIngredientsAdapter);
        recyclerView.setLayoutManager(gridLayoutManager1);

        ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {
            @Override
            public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
                Log.d(TAG, "onMove: ");
                return false;
            }

            @Override
            public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
                Log.d(TAG, "onSwiped: ");
            }
        };

        ItemTouchHelper touchHelper = new ItemTouchHelper(simpleItemTouchCallback);
        touchHelper.attachToRecyclerView(recyclerView);

Answer 1

我忘记了两件事:

**1。将 SimpleCallback 更新为:

ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {
            @Override
            public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
                // Notify Adapter of the moved item!
                recyclerView.getAdapter().notifyItemMoved(viewHolder.getAdapterPosition(), target.getAdapterPosition());
                return true;
            }

            @Override
            public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
                // No swipe action
            }

            @Override
            public boolean isItemViewSwipeEnabled() {
                // Disable swipe (dont override this method or return true, if you want to have swipe)
                return false;
            }

            @Override
            public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
                // Set movement flags to specify the movement direction
                // final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.RIGHT | ItemTouchHelper.LEFT;  <-- for all directions
                // In this case only up and down is allowed
                final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
                final int swipeFlags = 0;
                return makeMovementFlags(dragFlags, swipeFlags);
            }
        };

特别重要的是覆盖getMovementFlags()来指定拖动的方向并通知适配器移动的Item，就像我在onMove()中所做的那样

<强>2。通过 itemTouchHelper.startDrag(viewHolderElement) 触发拖动:

我通过在 RecyclerViewAdapter 中创建一个小界面来做到这一点:

public interface OnStartDragListener {
        void onStartDrag(RecyclerView.ViewHolder holder);
    }

创建适配器时，像这样传入一个新的 OnStartDragListenerElement:

EditIngredientsRecyclerViewAdapter premixableIngredientsAdapter = new EditIngredientsRecyclerViewAdapter(this, typeOfComponents, new EditIngredientsRecyclerViewAdapter.OnStartDragListener() {
            @Override
            public void onStartDrag(RecyclerView.ViewHolder holder) {
                touchHelper.startDrag(holder);
                Log.d(TAG, "onStartDrag: ");
            }
        });

并在 Touchlistener 中调用 onStartDrag(viewHolder) 放置在 View 中的按钮上，如下所示:

holder.itemBinding.dragBtn.setOnTouchListener(new View.OnTouchListener() {
                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    mOnStartDragListener.onStartDrag(holder);
                    return false;
                }
            });

我敢肯定，还有更有效的实现，一旦有人在这里发布一个，我就会接受。但是，这至少让它对我有用。