如何创建 RecyclerView 拖放(交换 2 个项目位置版本)
how to create RecyclerView drag and drop (swap 2 item positions version)
我有 ItemTouchHelper class,它使用滑动和拖放来执行操作。但我想改变拖放行为。它应该交换 2 个元素的位置,第一个是我拖动的,另一个是放置它的位置。我想交换拖放位置的项目。不要改变两者之间所有项目的位置。
怎么做
这是我的class拖放
public class ItemTouchHelper extends
androidx.recyclerview.widget.ItemTouchHelper.Callback {
private Drawable icon;
private Context context;
private ColorDrawable background;
private final ItemTouchHelperListener dragDropListener;
public ItemTouchHelper(Context context, Drawable icon,
ItemTouchHelperListener dragDropListener) {
this.icon = icon;
this.dragDropListener = dragDropListener;
this.context = context;
this.background = new ColorDrawable(context.getResources().getColor(R.color.deleteItem));
}
@Override
public void onChildDraw(@NonNull Canvas c, @NonNull RecyclerView recyclerView,
@NonNull RecyclerView.ViewHolder viewHolder,
float dX, float dY,
int actionState, boolean isCurrentlyActive) {
super.onChildDraw(c, recyclerView, viewHolder, dX,
dY, actionState, isCurrentlyActive);
View itemView = viewHolder.itemView;
int iconMargin = (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
int iconTop = itemView.getTop() + (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
int iconBottom = iconTop + icon.getIntrinsicHeight();
if (dX > 0) {
background = new ColorDrawable(context.getResources().getColor(R.color.deleteItem));
iconMargin = (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
iconTop = itemView.getTop() + (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
iconBottom = iconTop + icon.getIntrinsicHeight();
int iconRight = itemView.getLeft() + iconMargin + icon.getIntrinsicWidth();
int iconLeft = itemView.getLeft() + iconMargin;
icon.setBounds(iconLeft, iconTop, iconRight, iconBottom);
background.setBounds(itemView.getLeft(), itemView.getTop(),
itemView.getLeft() + ((int) dX),
itemView.getBottom());
} else if (dX < 0) {
int iconRight = itemView.getRight() - iconMargin;
int iconLeft = itemView.getRight() - iconMargin - icon.getIntrinsicWidth();
icon.setBounds(iconLeft, iconTop, iconRight, iconBottom);
background.setBounds(itemView.getRight(), itemView.getTop(),
itemView.getRight() + ((int) dX),
itemView.getBottom());
} else {
background.setBounds(0, 0, 0, 0);
icon.setBounds(0, 0, 0, 0);
}
background.draw(c);
icon.draw(c);
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder,
int direction) {
dragDropListener.deleteElementDialog(viewHolder.getAdapterPosition());
}
@Override
public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
int dragFlags = UP | DOWN;
int swipeFlags = START | END;
return makeMovementFlags(dragFlags, swipeFlags);
}
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder,
@NonNull RecyclerView.ViewHolder target) {
dragDropListener.onRowMoved(viewHolder.getAdapterPosition(), target.getAdapterPosition());
return true;
}
@Override
public void onSelectedChanged(RecyclerView.ViewHolder viewHolder,
int actionState) {
if (actionState != ACTION_STATE_IDLE && actionState != ACTION_STATE_SWIPE) {
dragDropListener.onRowSelected(viewHolder);
}
super.onSelectedChanged(viewHolder, actionState);
}
@Override
public void clearView(@NonNull RecyclerView recyclerView,
@NonNull RecyclerView.ViewHolder viewHolder) {
super.clearView(recyclerView, Objects.requireNonNull(viewHolder));
dragDropListener.onRowClear(Objects.requireNonNull(viewHolder));
}
@Override
public boolean isLongPressDragEnabled() {
return true;
}
}
这是我的 ItemTouchHelperListener:
public void setItemTouchHelperListener() {
ItemTouchHelperListener itemTouchHelperListener = new
ItemTouchHelperListener() {
@Override
public void onRowMoved(int fromPosition, int toPosition) {
presenter.rowMoved(fromPosition, toPosition);
}
@Override
public void onRowSelected(RecyclerView.ViewHolder myViewHolder) {
if (myViewHolder instanceof ElementsAdapter.ElementsViewHolder) {
elementsAdapter.rowSelected((ElementsAdapter.ElementsViewHolder) myViewHolder);
presenter.rowSelected(myViewHolder.getAdapterPosition());
}
}
@Override
public void onRowClear(RecyclerView.ViewHolder myViewHolder) {
if (myViewHolder instanceof ElementsAdapter.ElementsViewHolder) {
elementsAdapter.rowClear((ElementsAdapter.ElementsViewHolder) myViewHolder);
presenter.rowClear(myViewHolder.getAdapterPosition());
}
}
@Override
public void deleteElementDialog(int adapterPosition) {
createDeleteDialog(adapterPosition);
}
};
您可以通过使用 onMove() 方法注册拖动的项目和使用 clearView() 方法注册拖放的项目来实现此目的;然后修改 RecyclerView
适配器的数据源;因此您可以使用存储拖动项目的临时项目;然后将拖放的项目设置为拖放的项目;最后将临时项目放在掉落的项目上。
然后利用 RecyclerView
适配器 notifyItemChanged()
为这两个项目更新布局
注意:这里我禁用了滑动,因为你的问题主要是拖放
final int[] oldPos = new int[1];
final int[] newPos = new int[1];
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(
ItemTouchHelper.UP |
ItemTouchHelper.DOWN |
ItemTouchHelper.LEFT |
ItemTouchHelper.RIGHT,
0) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
oldPos[0] = viewHolder.getAdapterPosition();
newPos[0] = target.getAdapterPosition();
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
}
@Override
public void clearView(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
super.clearView(recyclerView, viewHolder);
moveItem(oldPos[0], newPos[0]);
}
});
private void moveItem(int oldPos, int newPos) {
Item temp = mItems.get(oldPos);
mItems.set(oldPos, mItems.get(newPos));
mItems.set(newPos, temp);
mAdapter.notifyItemChanged(oldPos);
mAdapter.notifyItemChanged(newPos);
}
结果
我完全同意@Zain 的回答,但有一个问题,即假设您想用第 3 项替换第 1 项,然后您将单击并按住第 3 项并将其拖到第 1 项上。放下后,您会注意到第 3 个项目将再次移动到其原始位置,之后,两个项目都会正确更新。不好看。
我刚刚稍微修改了@Zain 的回答。
private int fromPos = -1;
private int toPos = -1;
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new
ItemTouchHelper.SimpleCallback(
ItemTouchHelper.UP | ItemTouchHelper.DOWN |
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT, 0) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView,
@NonNull RecyclerView.ViewHolder viewHolder,
@NonNull RecyclerView.ViewHolder target) {
toPos = target.getAdapterPosition();
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder,
int direction) {}
@Override
public void onSelectedChange(@NonNull RecyclerView.ViewHolder
viewHolder, int actionState) {
switch(actionState){
case ItemTouchHelper.ACTION_STATE_DRAG:{
fromPos = viewHolder.getAdapterPosition();
break;
}
case ItemTouchHelper.ACTION_STATE_IDLE: {
//Execute when the user dropped the item after dragging.
if(fromPos != -1 && toPos != -1
&& fromPos != toPos) {
moveItem(fromPos, toPos);
fromPos = -1;
toPos = -1;
}
break;
}
}
private void moveItem(int oldPos, int newPos) {
Item temp = mItems.get(oldPos);
mItems.set(oldPos, mItems.get(newPos));
mItems.set(newPos, temp);
mAdapter.notifyItemChanged(oldPos);
mAdapter.notifyItemChanged(newPos);
}
我有 ItemTouchHelper class,它使用滑动和拖放来执行操作。但我想改变拖放行为。它应该交换 2 个元素的位置,第一个是我拖动的,另一个是放置它的位置。我想交换拖放位置的项目。不要改变两者之间所有项目的位置。
怎么做
这是我的class拖放
public class ItemTouchHelper extends
androidx.recyclerview.widget.ItemTouchHelper.Callback {
private Drawable icon;
private Context context;
private ColorDrawable background;
private final ItemTouchHelperListener dragDropListener;
public ItemTouchHelper(Context context, Drawable icon,
ItemTouchHelperListener dragDropListener) {
this.icon = icon;
this.dragDropListener = dragDropListener;
this.context = context;
this.background = new ColorDrawable(context.getResources().getColor(R.color.deleteItem));
}
@Override
public void onChildDraw(@NonNull Canvas c, @NonNull RecyclerView recyclerView,
@NonNull RecyclerView.ViewHolder viewHolder,
float dX, float dY,
int actionState, boolean isCurrentlyActive) {
super.onChildDraw(c, recyclerView, viewHolder, dX,
dY, actionState, isCurrentlyActive);
View itemView = viewHolder.itemView;
int iconMargin = (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
int iconTop = itemView.getTop() + (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
int iconBottom = iconTop + icon.getIntrinsicHeight();
if (dX > 0) {
background = new ColorDrawable(context.getResources().getColor(R.color.deleteItem));
iconMargin = (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
iconTop = itemView.getTop() + (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
iconBottom = iconTop + icon.getIntrinsicHeight();
int iconRight = itemView.getLeft() + iconMargin + icon.getIntrinsicWidth();
int iconLeft = itemView.getLeft() + iconMargin;
icon.setBounds(iconLeft, iconTop, iconRight, iconBottom);
background.setBounds(itemView.getLeft(), itemView.getTop(),
itemView.getLeft() + ((int) dX),
itemView.getBottom());
} else if (dX < 0) {
int iconRight = itemView.getRight() - iconMargin;
int iconLeft = itemView.getRight() - iconMargin - icon.getIntrinsicWidth();
icon.setBounds(iconLeft, iconTop, iconRight, iconBottom);
background.setBounds(itemView.getRight(), itemView.getTop(),
itemView.getRight() + ((int) dX),
itemView.getBottom());
} else {
background.setBounds(0, 0, 0, 0);
icon.setBounds(0, 0, 0, 0);
}
background.draw(c);
icon.draw(c);
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder,
int direction) {
dragDropListener.deleteElementDialog(viewHolder.getAdapterPosition());
}
@Override
public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
int dragFlags = UP | DOWN;
int swipeFlags = START | END;
return makeMovementFlags(dragFlags, swipeFlags);
}
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder,
@NonNull RecyclerView.ViewHolder target) {
dragDropListener.onRowMoved(viewHolder.getAdapterPosition(), target.getAdapterPosition());
return true;
}
@Override
public void onSelectedChanged(RecyclerView.ViewHolder viewHolder,
int actionState) {
if (actionState != ACTION_STATE_IDLE && actionState != ACTION_STATE_SWIPE) {
dragDropListener.onRowSelected(viewHolder);
}
super.onSelectedChanged(viewHolder, actionState);
}
@Override
public void clearView(@NonNull RecyclerView recyclerView,
@NonNull RecyclerView.ViewHolder viewHolder) {
super.clearView(recyclerView, Objects.requireNonNull(viewHolder));
dragDropListener.onRowClear(Objects.requireNonNull(viewHolder));
}
@Override
public boolean isLongPressDragEnabled() {
return true;
}
}
这是我的 ItemTouchHelperListener:
public void setItemTouchHelperListener() {
ItemTouchHelperListener itemTouchHelperListener = new
ItemTouchHelperListener() {
@Override
public void onRowMoved(int fromPosition, int toPosition) {
presenter.rowMoved(fromPosition, toPosition);
}
@Override
public void onRowSelected(RecyclerView.ViewHolder myViewHolder) {
if (myViewHolder instanceof ElementsAdapter.ElementsViewHolder) {
elementsAdapter.rowSelected((ElementsAdapter.ElementsViewHolder) myViewHolder);
presenter.rowSelected(myViewHolder.getAdapterPosition());
}
}
@Override
public void onRowClear(RecyclerView.ViewHolder myViewHolder) {
if (myViewHolder instanceof ElementsAdapter.ElementsViewHolder) {
elementsAdapter.rowClear((ElementsAdapter.ElementsViewHolder) myViewHolder);
presenter.rowClear(myViewHolder.getAdapterPosition());
}
}
@Override
public void deleteElementDialog(int adapterPosition) {
createDeleteDialog(adapterPosition);
}
};
您可以通过使用 onMove() 方法注册拖动的项目和使用 clearView() 方法注册拖放的项目来实现此目的;然后修改 RecyclerView
适配器的数据源;因此您可以使用存储拖动项目的临时项目;然后将拖放的项目设置为拖放的项目;最后将临时项目放在掉落的项目上。
然后利用 RecyclerView
适配器 notifyItemChanged()
为这两个项目更新布局
注意:这里我禁用了滑动,因为你的问题主要是拖放
final int[] oldPos = new int[1];
final int[] newPos = new int[1];
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(
ItemTouchHelper.UP |
ItemTouchHelper.DOWN |
ItemTouchHelper.LEFT |
ItemTouchHelper.RIGHT,
0) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
oldPos[0] = viewHolder.getAdapterPosition();
newPos[0] = target.getAdapterPosition();
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
}
@Override
public void clearView(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
super.clearView(recyclerView, viewHolder);
moveItem(oldPos[0], newPos[0]);
}
});
private void moveItem(int oldPos, int newPos) {
Item temp = mItems.get(oldPos);
mItems.set(oldPos, mItems.get(newPos));
mItems.set(newPos, temp);
mAdapter.notifyItemChanged(oldPos);
mAdapter.notifyItemChanged(newPos);
}
结果
我完全同意@Zain 的回答,但有一个问题,即假设您想用第 3 项替换第 1 项,然后您将单击并按住第 3 项并将其拖到第 1 项上。放下后,您会注意到第 3 个项目将再次移动到其原始位置,之后,两个项目都会正确更新。不好看。
我刚刚稍微修改了@Zain 的回答。
private int fromPos = -1;
private int toPos = -1;
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new
ItemTouchHelper.SimpleCallback(
ItemTouchHelper.UP | ItemTouchHelper.DOWN |
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT, 0) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView,
@NonNull RecyclerView.ViewHolder viewHolder,
@NonNull RecyclerView.ViewHolder target) {
toPos = target.getAdapterPosition();
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder,
int direction) {}
@Override
public void onSelectedChange(@NonNull RecyclerView.ViewHolder
viewHolder, int actionState) {
switch(actionState){
case ItemTouchHelper.ACTION_STATE_DRAG:{
fromPos = viewHolder.getAdapterPosition();
break;
}
case ItemTouchHelper.ACTION_STATE_IDLE: {
//Execute when the user dropped the item after dragging.
if(fromPos != -1 && toPos != -1
&& fromPos != toPos) {
moveItem(fromPos, toPos);
fromPos = -1;
toPos = -1;
}
break;
}
}
private void moveItem(int oldPos, int newPos) {
Item temp = mItems.get(oldPos);
mItems.set(oldPos, mItems.get(newPos));
mItems.set(newPos, temp);
mAdapter.notifyItemChanged(oldPos);
mAdapter.notifyItemChanged(newPos);
}