我有一个项目，我需要用两种方式在一行上滑动才能启动一个 Action 。 向左滑动应该从特定列表中删除有问题的项目(而不是从原始列表中删除它，从而将其留在 recyclerview 数据集中)，向右滑动应该将有问题的项目添加到另一个列表(同样不是原始列表) . 我实现了一个 ItemTouchHelperAdapter 和一个 ItemTouchHelperCallback，我可以检测到向右/向左的滑动，但是 View 从屏幕上移开，剩下一个空白矩形。有什么想法吗？

public interface ItemTouchHelperAdapter {

/**
 * Called when an item has been dismissed by a swipe.<br/>
 * <br/>
 * Implementations should call {@link RecyclerView.Adapter#notifyItemRemoved(int)} after
 * adjusting the underlying data to reflect this removal.
 *
 * @param position The position of the item dismissed.
 * @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
 * @see RecyclerView.ViewHolder#getAdapterPosition()
 */
void onItemLeftSwipe(int position);

void onItemRightSwipe(int position);
}

ItemTouchHelperCallback

public class ItemTouchHelperCallback extends ItemTouchHelper.Callback {

private final ItemTouchHelperAdapter mAdapter;

public ItemTouchHelperCallback(ItemTouchHelperAdapter adapter) {
    mAdapter = adapter;
}

@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    // int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
    int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END;
    return makeMovementFlags(0, swipeFlags);
}

@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
    return false;
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    if (direction == ItemTouchHelper.START)
        mAdapter.onItemLeftSwipe(viewHolder.getAdapterPosition());
    else if (direction == ItemTouchHelper.END)
        mAdapter.onItemRightSwipe(viewHolder.getAdapterPosition());
    else
        System.out.println("direction: " + direction);
}

@Override
public boolean isLongPressDragEnabled() {
    return false;
}

@Override
public boolean isItemViewSwipeEnabled() {
    return true;
 }

}

这是在我的适配器类中:

    @Override
public void onItemLeftSwipe(int position) {

    System.out.println("swiped left on " + mDataset.get(position).getName());

}

@Override
public void onItemRightSwipe(int position) {

    System.out.println("swiped right on " + mDataset.get(position).getName());

}

最佳答案

public class MainActivity extends AppCompatActivity {
    RecyclerView mRecyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        setUpRecyclerView();

    }
    private void setUpRecyclerView() {
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(new TestAdapter());
        mRecyclerView.setHasFixedSize(true);
        setUpItemTouchHelper();
        setUpAnimationDecoratorHelper();
    }
    private void setUpItemTouchHelper() {

        ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
            Drawable background;
            Drawable xMark;
            int xMarkMargin;
            boolean initiated;
            private void init() {
                background = new ColorDrawable(Color.WHITE);
                xMark = ContextCompat.getDrawable(MainActivity.this, R.drawable.ic_clear_24dp);
                xMark.setColorFilter(Color.WHITE, PorterDuff.Mode.SRC_ATOP);
                xMarkMargin = (int) MainActivity.this.getResources().getDimension(R.dimen.ic_clear_margin);
                initiated = true;
            }
            @Override
            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                return false;
            }

            @Override
            public int getSwipeDirs(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder)
            {
                int position = viewHolder.getAdapterPosition();
                TestAdapter testAdapter = (TestAdapter)recyclerView.getAdapter();
                if (testAdapter.isUndoOn() && testAdapter.isPendingRemoval(position))
                {
                    return 0;
                }
                return super.getSwipeDirs(recyclerView, viewHolder);
            }

            @Override
            public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
                int swipedPosition = viewHolder.getAdapterPosition();
                TestAdapter adapter = (TestAdapter)mRecyclerView.getAdapter();
                boolean undoOn = adapter.isUndoOn();
                if (undoOn) {
                    adapter.pendingRemoval(swipedPosition);
                } else {
                    adapter.remove(swipedPosition);
                }
            }

            @Override
            public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
                View itemView = viewHolder.itemView;
                if (viewHolder.getAdapterPosition() == -1) {
                    return;
                }
                if (!initiated) {
                    init();
                }
                background.setBounds(itemView.getRight() + (int) dX, itemView.getTop(), itemView.getRight(), itemView.getBottom());
                background.draw(c);

                int itemHeight = itemView.getBottom() - itemView.getTop();
                int intrinsicWidth = xMark.getIntrinsicWidth();
                int intrinsicHeight = xMark.getIntrinsicWidth();
                int xMarkLeft = itemView.getRight() - xMarkMargin - intrinsicWidth;
                int xMarkRight = itemView.getRight() - xMarkMargin;
                int xMarkTop = itemView.getTop() + (itemHeight - intrinsicHeight)/2;
                int xMarkBottom = xMarkTop + intrinsicHeight;
                xMark.setBounds(xMarkLeft, xMarkTop, xMarkRight, xMarkBottom);
                xMark.draw(c);
                super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
            }

        };
        ItemTouchHelper mItemTouchHelper = new ItemTouchHelper(simpleItemTouchCallback);
        mItemTouchHelper.attachToRecyclerView(mRecyclerView);
    }
    private void setUpAnimationDecoratorHelper() {
        mRecyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
            Drawable background;
            boolean initiated;
            private void init() {
                background = new ColorDrawable(Color.RED);
                initiated = true;
            }
            @Override
            public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {

                if (!initiated) {
                    init();
                }
                if (parent.getItemAnimator().isRunning())
                {
                    View lastViewComingDown = null;
                    View firstViewComingUp = null;
                    int left = parent.getHeight();
                    int right = parent.getWidth();
                    int top = 0;
                    int bottom = 0;
                    int childCount = parent.getLayoutManager().getChildCount();
                    for (int i = 0; i < childCount; i++) {
                        View child = parent.getLayoutManager().getChildAt(i);
                        if (child.getTranslationY() < 0) {
                            // view is coming down
                            lastViewComingDown = child;
                        } else if (child.getTranslationY() > 0) {
                            // view is coming up
                            if (firstViewComingUp == null) {
                                firstViewComingUp = child;
                            }
                        }
                    }

                    if (lastViewComingDown != null && firstViewComingUp != null) {
                        // views are coming down AND going up to fill the void
                        top = lastViewComingDown.getBottom() + (int) lastViewComingDown.getTranslationY();
                        bottom = firstViewComingUp.getTop() + (int) firstViewComingUp.getTranslationY();
                    } else if (lastViewComingDown != null) {
                        // views are going down to fill the void
                        top = lastViewComingDown.getBottom() + (int) lastViewComingDown.getTranslationY();
                        bottom = lastViewComingDown.getBottom();
                    } else if (firstViewComingUp != null) {
                        // views are coming up to fill the void
                        top = firstViewComingUp.getTop();
                        bottom = firstViewComingUp.getTop() + (int) firstViewComingUp.getTranslationY();
                    }

                    background.setBounds(left, top, right, bottom);
                    background.draw(c);

                }
                super.onDraw(c, parent, state);
            }

        });
    }

    class TestAdapter extends RecyclerView.Adapter {

        private static final int PENDING_REMOVAL_TIMEOUT = 3000; // 3sec

        List<String> items;
        List<String> itemsPendingRemoval;
        int lastInsertedIndex; // so we can add some more items for testing purposes
        boolean undoOn; // is undo on, you can turn it on from the toolbar menu

        private Handler handler = new Handler(); // hanlder for running delayed runnables
        HashMap<String, Runnable> pendingRunnables = new HashMap<>(); // map of items to pending runnables, so we can cancel a removal if need be

        public TestAdapter() {
            items = new ArrayList<>();
            itemsPendingRemoval = new ArrayList<>();
            // let's generate some items
            lastInsertedIndex = 15;
            // this should give us a couple of screens worth
            for (int i=1; i<= lastInsertedIndex; i++) {
                items.add("Item " + i);
            }
        }

        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            return new TestViewHolder(parent);
        }

        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
            TestViewHolder viewHolder = (TestViewHolder)holder;
            final String item = items.get(position);

            if (itemsPendingRemoval.contains(item)) {
                // we need to show the "undo" state of the row
                //viewHolder.itemView.setBackgroundColor(Color.RED);
                viewHolder.itemView.setBackgroundColor(Color.WHITE);
                viewHolder.titleTextView.setVisibility(View.GONE);
                //viewHolder.undoButton.setVisibility(View.VISIBLE);
                viewHolder.undoButton.setVisibility(View.GONE);
                viewHolder.undoButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        // user wants to undo the removal, let's cancel the pending task
                        Runnable pendingRemovalRunnable = pendingRunnables.get(item);
                        pendingRunnables.remove(item);
                        if (pendingRemovalRunnable != null) handler.removeCallbacks(pendingRemovalRunnable);
                        itemsPendingRemoval.remove(item);
                        // this will rebind the row in "normal" state
                        notifyItemChanged(items.indexOf(item));
                    }
                });
            } else {
                // we need to show the "normal" state
                viewHolder.itemView.setBackgroundColor(Color.WHITE);
                viewHolder.titleTextView.setVisibility(View.VISIBLE);
                viewHolder.titleTextView.setText(item);
                viewHolder.undoButton.setVisibility(View.GONE);
                viewHolder.undoButton.setOnClickListener(null);
            }
        }

        @Override
        public int getItemCount() {
            return items.size();
        }

        public void addItems(int howMany){
            if (howMany > 0) {
                for (int i = lastInsertedIndex + 1; i <= lastInsertedIndex + howMany; i++) {
                    items.add("Item " + i);
                    notifyItemInserted(items.size() - 1);
                }
                lastInsertedIndex = lastInsertedIndex + howMany;
            }
        }

        public void setUndoOn(boolean undoOn) {
            this.undoOn = undoOn;
        }

        public boolean isUndoOn() {
            return undoOn;
        }

        public void pendingRemoval(int position) {
            final String item = items.get(position);
            if (!itemsPendingRemoval.contains(item)) {
                itemsPendingRemoval.add(item);
                // this will redraw row in "undo" state
                notifyItemChanged(position);
                // let's create, store and post a runnable to remove the item
                Runnable pendingRemovalRunnable = new Runnable() {
                    @Override
                    public void run() {
                        remove(items.indexOf(item));
                    }
                };
                handler.postDelayed(pendingRemovalRunnable, PENDING_REMOVAL_TIMEOUT);
                pendingRunnables.put(item, pendingRemovalRunnable);
            }
        }
        public void remove(int position) {
            String item = items.get(position);
            if (itemsPendingRemoval.contains(item)) {
                itemsPendingRemoval.remove(item);
            }
            if (items.contains(item)) {
                items.remove(position);
                notifyItemRemoved(position);
            }
        }

        public boolean isPendingRemoval(int position) {
            String item = items.get(position);
            return itemsPendingRemoval.contains(item);
        }
    }
    static class TestViewHolder extends RecyclerView.ViewHolder
    {
        TextView titleTextView;
        Button undoButton;
        public TestViewHolder(ViewGroup parent)
        {
            super(LayoutInflater.from(parent.getContext()).inflate(R.layout.row_view, parent, false));
            titleTextView = (TextView) itemView.findViewById(R.id.title_text_view);
            undoButton = (Button) itemView.findViewById(R.id.undo_button);
        }
    }
}

关于android - 如何在不关闭的情况下在android中的recyclerview上滑动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37388676/