问题描述
我想实现拖放到RecyclerView中。我发现，实现此目标的最佳方法是将itemtouchhelper附加到RecyclerView。
onSwiped()工作正常，但从未触发onMove()。
这就是我要做的：
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);
解决方法
对不起，我没有足够的声誉在这个问题下发表评论。尝试将return false更改为return true
我忘了两件事：
** 1。将SimpleCallback更新为此：
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);
}
};
尤为重要的是，像我在getMovementFlags()中所做的那样，覆盖onMove()以指定拖动方向并通知适配器已移动的物品
2。触发拖动itemTouchHelper.startDrag(viewHolderElement)：
我是通过在RecyclerViewAdapter中创建一个小界面来做到这一点的：
public interface OnStartDragListener {
void onStartDrag(RecyclerView.ViewHolder holder);
}
创建适配器时，在新的OnStartDragListenerElement中传递，如下所示：
EditIngredientsRecyclerViewAdapter premixableIngredientsAdapter = new EditIngredientsRecyclerViewAdapter(this,typeOfComponents,new EditIngredientsRecyclerViewAdapter.OnStartDragListener() {
@Override
public void onStartDrag(RecyclerView.ViewHolder holder) {
touchHelper.startDrag(holder);
Log.d(TAG,"onStartDrag: ");
}
});
并在放置在视图中的按钮上的Touchlistener中调用onStartDrag(viewHolder)，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，会有更有效的实现，一旦有人在这里发布了，我就会接受。但是，这至少使它对我有用。
,我已经列出了ItemTouchHelper.SimpleCallback和ItemTouchHelper.Callback（）的代码。代码中列出了注释，以帮助了解发生的情况。
ItemTouchHelper.SimpleCallback 在RecyclerView实现下的“活动/片段”中，创建一个ItemTouchHelper.SimpleCallback对象。您需要重写onMove（）和onSwiped（）方法。
ItemTouchHelper(object : ItemTouchHelper.SimpleCallback(
ItemTouchHelper.UP or ItemTouchHelper.DOWN,ItemTouchHelper.RIGHT or ItemTouchHelper.LEFT
) {
// You'll need to Override
override fun onMove(
recyclerView: RecyclerView,viewHolder: ViewHolder,target: ViewHolder
): Boolean {
// Get the position start position of the item
val startPosition = viewHolder.adapterPosition
// Get the endPosition,where you draged it to.
val endPosition = target.adapterPosition
// Submit start and end position to notifyItemMoved.
recyclerView.adapter?.notifyItemMoved(startPosition,endPosition)
// true if moved,false otherwise
return true
}
override fun onSwiped ...
如果要创建CustomItemTouchCallback
创建一个扩展ItemTouchHelper.Callback（）的customItemTouchHelper类，您将需要重写getMovementFlags（），onMove（）和onSwiped（）
class CustomItemTouchHelper(mContext: Context,val viewModel: MyViewModel) : ItemTouchHelper.Callback() {
override fun getMovementFlags(
recyclerView: RecyclerView,viewHolder: RecyclerView.ViewHolder
): Int {
val dragFlags = ItemTouchHelper.UP or ItemTouchHelper.DOWN
val swipeFlags = ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT
return makeMovementFlags(dragFlags,swipeFlags)
}
override fun onMove(
recyclerView: RecyclerView,viewHolder: RecyclerView.ViewHolder,target: RecyclerView.ViewHolder
): Boolean {
val startPosition = viewHolder.adapterPosition
val endPosition = target.adapterPosition
recyclerView.adapter?.notifyItemMoved(fromPosition,toPosition)
// true if moved,false otherwise
return true
}
override fun onSwiped(viewHolder: RecyclerView.ViewHolder,direction: Int) {
val editList: MutableList<User>? = viewModel.usersList?.value as MutableList<User>?
val editListCopy = editList?.toMutableList()
editListCopy?.removeAt(viewHolder.adapterPosition)
viewModel.usersList?.postValue(editListCopy)
}
override fun isItemViewSwipeEnabled(): Boolean {
// Allows items to be swiped left or right.
return true
}
override fun isLongPressDragEnabled(): Boolean {
// Allows for long click so items can be dragged,moved up or down in the list.
return true
}
}
现在，在“活动”或“片段”中，您需要创建一个CustomItemHelper对象，然后将RecyclerView附加到该对象。
val rv = findViewById<RecyclerView>(R.id.recycler_view)
rv.apply {
...
val customItemTouchHelper = ItemTouchHelper(CustomItemTouchHelper(context,viewModel))
customItemTouchHelper.attachToRecyclerView(rv)
}