我试图允许滑动以移除回收者视图的项目，但由于某种原因，它并不总是很好地播放，显示空格而不是卡片。
我已经使代码处理投掷和移动项目，触发滑动动画，当滑动动画结束时，项目将从数据集中删除并通知适配器。
也许是因为我是RecyclerView的新手，但我找不到什么。
public class MainActivity extends ActionBarActivity
{
private RecyclerView mRecyclerView;
private LinearLayoutManager mLayoutManager;
private MyAdapter mAdapter;
private static final int DATA_COUNT=100;
private ArrayList<String> mDataSet;
@Override
protected void onCreate(final Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView=(RecyclerView)findViewById(R.id.my_recycler_view);
mRecyclerView.setHasFixedSize(true);
mLayoutManager=new LinearLayoutManager(this);
// TODO in case we use GridLayoutManager, consider using this: http://stackoverflow.com/q/26869312/878126
mRecyclerView.setLayoutManager(mLayoutManager);
mDataSet=new ArrayList<String>(DATA_COUNT);
for(int i=0;i<DATA_COUNT;++i)
mDataSet.add(Integer.toString(i));
mAdapter=new MyAdapter(mDataSet);
mRecyclerView.setAdapter(mAdapter);
}
// ///////////////////////////////////////////////////////////////
// MyAdapter//
// ///////////
public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>
{
private final ArrayList<String> mDataset;
public class ItemViewType
{
private static final int HEADER=0, ITEM=1;
}
public MyAdapter(final ArrayList<String> myDataset)
{
mDataset=myDataset;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(final ViewGroup parent,final int viewType)
{
final RecyclerView.ViewHolder holder;
final View rootView;
switch(viewType)
{
case ItemViewType.HEADER:
rootView=LayoutInflater.from(parent.getContext()).inflate(R.layout.header,parent,false);
holder=new HeaderViewHoler(rootView);
break;
case ItemViewType.ITEM:
rootView=LayoutInflater.from(parent.getContext()).inflate(R.layout.card,parent,false);
holder=new ItemViewHolder(rootView);
rootView.setAlpha(1);
rootView.setTranslationX(0);
rootView.setTranslationY(0);
handleSwiping(rootView,holder);
break;
default:
holder=null;
break;
}
return holder;
}
private void handleSwiping(final View rootView,final RecyclerView.ViewHolder holder)
{
final GestureDetectorCompat gestureDetector=new GestureDetectorCompat(rootView.getContext(),
new GestureDetector.OnGestureListener()
{
...
@Override
public boolean onFling(final MotionEvent e1,final MotionEvent e2,final float velocityX,
final float velocityY)
{
final int viewSwipeThreshold=rootView.getWidth()/4;
if(velocityX<-viewSwipeThreshold)
{
onSwipe(rootView,holder.getPosition(),false);
return true;
}
else if(velocityX>viewSwipeThreshold)
{
onSwipe(rootView,holder.getPosition(),true);
return true;
}
return false;
}
});
rootView.setOnTouchListener(new View.OnTouchListener()
{
private final float originalX=0;
private final float originalY=0;
private float startMoveX=0;
private float startMoveY=0;
@Override
public boolean onTouch(final View view,final MotionEvent event)
{
final int viewSwipeHorizontalThreshold=rootView.getWidth()/3;
final int viewSwipeVerticalThreshold=view.getContext().getResources()
.getDimensionPixelSize(R.dimen.vertical_swipe_threshold);
if(gestureDetector.onTouchEvent(event))
return true;
final float x=event.getRawX(), y=event.getRawY();
final float deltaX=x-startMoveX, deltaY=y-startMoveY;
switch(event.getAction()&MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN:
startMoveX=x;
startMoveY=y;
break;
case MotionEvent.ACTION_UP:
if(Math.abs(deltaX)<viewSwipeHorizontalThreshold)
{
rootView.animate().translationX(originalX).translationY(originalY).alpha(1).start();
if(Math.abs(deltaY)<viewSwipeHorizontalThreshold)
rootView.performClick();
}
else if(deltaX<0)
onSwipe(rootView,holder.getPosition(),true);
else
onSwipe(rootView,holder.getPosition(),false);
break;
case MotionEvent.ACTION_CANCEL:
if(Math.abs(deltaX)<viewSwipeHorizontalThreshold
||Math.abs(deltaY)<viewSwipeVerticalThreshold)
rootView.animate().translationX(originalX).translationY(originalY).alpha(1).start();
else if(deltaX<0)
onSwipe(rootView,holder.getPosition(),true);
else
onSwipe(rootView,holder.getPosition(),false);
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_POINTER_UP:
break;
case MotionEvent.ACTION_MOVE:
rootView.setAlpha(Math.max(Math.min((255-Math.abs(deltaX))/255f,1.0f),0.1f));
rootView.setTranslationX(deltaX);
break;
}
return true;
}
});
}
@Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder,final int position)
{
final int itemViewType=getItemViewType(position);
final View rootView=holder.itemView;
rootView.setAlpha(1);
rootView.setTranslationX(0);
rootView.setTranslationY(0);
}
private void onSwipe(final View rootView,final int position,final boolean isToLeft)
{
ViewPropertyAnimator animator;
if(isToLeft)
animator=rootView.animate().translationX(-rootView.getWidth());
else
animator=rootView.animate().translationX(rootView.getWidth());
animator.setListener(new Animator.AnimatorListener()
{
@Override
public void onAnimationStart(Animator animation)
{
}
@Override
public void onAnimationEnd(Animator animation)
{
rootView.setAlpha(1);
mDataset.remove(position);
notifyItemRemoved(position);
}
@Override
public void onAnimationCancel(Animator animation)
{
}
@Override
public void onAnimationRepeat(Animator animation)
{
}
});
animator.start();
}
@Override
public int getItemCount()
{
return mDataset.size()+1;
}
@Override
public int getItemViewType(final int position)
{
return position==0?ItemViewType.HEADER:ItemViewType.ITEM;
}
}
// ///////////////////////////////////////
// HeaderViewHoler //
// //////////////////
public static class HeaderViewHoler extends RecyclerView.ViewHolder
{
public TextView mTextView;
public HeaderViewHoler(final View v)
{
super(v);
}
}
// ///////////////////////////////////////
// ItemViewHolder //
// /////////////////
public static class ItemViewHolder extends RecyclerView.ViewHolder
{
public ItemViewHolder(final View rootView)
{
super(rootView);
rootView.setAlpha(1);
rootView.setTranslationX(0);
rootView.setTranslationY(0);
}
}
}
我做了什么错？为什么它有时运作良好，有时不运作？
是否有更好的解决方案可以进行滑动到移除处理？
答案 0 :(得分：3)
您无法访问回调中的position参数，因为RecyclerView不会因为其位置已更改而重新绑定ViewHolder。删除项目会更改其下方所有项目的位置，因此这些项目的所有位置参考都将过时。
相反，您可以使用ViewHolder#getPosition在用户操作时获取最新位置。
除此之外，不要在onBind中添加手势监听器和触摸监听器，而是在创建ViewHolder时添加它们。这样，每次项目反弹时，您都将避免创建新对象。
评论更新。建议的更改：
@Override
public RecyclerView.ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
RecyclerView.ViewHolder holder = null;
View rootView;
switch (viewType) {
case ItemViewType.HEADER:
rootView = LayoutInflater.from(parent.getContext()).inflate(R.layout.header, parent, false);
holder = new HeaderViewHoler(rootView);
break;
case ItemViewType.ITEM:
rootView = LayoutInflater.from(parent.getContext()).inflate(R.layout.card, parent, false);
holder = new ItemViewHolder(rootView);
//initialize gesture detector and touch listener, replace position with getPosiiton
}
return holder;
}