我有一个项目，我需要以两种方式在一行上滑动以启动操作。 向左滑动应从特定列表中删除有问题的项目（不将其从原始列表中删除，因此将其保留在recyclerview数据集中），向右滑动应将相关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，我可以检测到左/右滑动，但视图会从屏幕上移开，我留下一个空白矩形。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);
}
公共类ItemTouchHelperCallback扩展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;
}
}
这是我的适配器类：
@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());
}
答案 0 :(得分：3)
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);
}
}
}
答案 1 :(得分：1)
我不确定这是否是最佳解决方案和最有效的解决方案，但我刚刚删除了该项目并再次添加：
@Override
public void onItemLeftSwipe(int position) {
// modify your item as you wish
mDataset.add(position, mDataset.get(position));
notifyItemInserted(position);
mDataset.remove(position + 1);
notifyItemRemoved(position + 1);
}
@Override
public void onItemRightSwipe(int position) {
// modify your item as you wish
mDataset.add(position, mDataset.get(position));
notifyItemInserted(position);
mDataset.remove(position + 1);
notifyItemRemoved(position + 1);
}
答案 2 :(得分：1)
使用此类为适配器类中的每个项实现滑动侦听器。
public class OnSwipeTouchListener implements OnTouchListener {
private final GestureDetector gestureDetector;
public OnSwipeTouchListener (Context ctx){
gestureDetector = new GestureDetector(ctx, new GestureListener());
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
private final class GestureListener extends SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
@Override
public boolean onDown(MotionEvent e) {
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
boolean result = false;
try {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
onSwipeRight();
} else {
onSwipeLeft();
}
}
result = true;
}
else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
onSwipeBottom();
} else {
onSwipeTop();
}
}
result = true;
} catch (Exception exception) {
exception.printStackTrace();
}
return result;
}
}
public void onSwipeRight() {
}
public void onSwipeLeft() {
}
public void onSwipeTop() {
}
public void onSwipeBottom() {
}
}
在适配器类中：
itemView.setOnTouchListener(new OnSwipeTouchListener(getActivity()) {
public void onSwipeTop() {
}
public void onSwipeRight() {
}
public void onSwipeLeft() {
}
public void onSwipeBottom() {
}
});