问题
I am trying to implement a horizontal recyclerview and each item of the recyclerview will be a vertical recyclerview with a grid layout. The problem that i am facing is that when I try to scroll the child recyclerview vertically sometimes the parent recyclerview takes the scroll and starts scrolling horizontally. The approaches I tried to fix this are,
setNestedScrollingEnabled(false)on the parentrecyclerview- In the
onTouch()of the childrecyclerviewI disable touch events on the parentrecyclerviewby calledrequestdisallowinterceptTouchevent(false)
None of the above solutions provide a perfect fix for the problem. Any help is appreciated
回答1:
The problem seemed interesting to me. So I tried to implement and this is what I achieved (you can also see the video here) which is pretty smooth.
So you can try something like this:
Define CustomLinearLayoutManager extending LinearLayoutManager like this:
public class CustomLinearLayoutManager extends LinearLayoutManager {
public CustomLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
@Override
public boolean canScrollVertically() {
return false;
}
}
and set this CustomLinearLayoutManager to your parent RecyclerView.
RecyclerView parentRecyclerView = (RecyclerView)findViewById(R.id.parent_rv);
CustomLinearLayoutManager customLayoutManager = new CustomLinearLayoutManager(this, LinearLayoutManager.HORIZONTAL,false);
parentRecyclerView.setLayoutManager(customLayoutManager);
parentRecyclerView.setAdapter(new ParentAdapter(this)); // some adapter
Now for child RecyclerView, define custom CustomGridLayoutManager extending GridLayoutManager:
public class CustomGridLayoutManager extends GridLayoutManager {
public CustomGridLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
public CustomGridLayoutManager(Context context, int spanCount) {
super(context, spanCount);
}
public CustomGridLayoutManager(Context context, int spanCount, int orientation, boolean reverseLayout) {
super(context, spanCount, orientation, reverseLayout);
}
@Override
public boolean canScrollHorizontally() {
return false;
}
}
and set it as layoutManger to the child RecyclerView:
childRecyclerView = (RecyclerView)itemView.findViewById(R.id.child_rv);
childRecyclerView.setLayoutManager(new CustomGridLayoutManager(context, 3));
childRecyclerView.setAdapter(new ChildAdapter()); // some adapter
So basically parent RecyclerView is only listening to horizontal scrolls and child RecyclerView is only listening to vertical scrolls.
Along with that, if you also want to handle diagonal swipe (which is little skewed to either vertical or horizontal), you can include a gesture listener in the parent RecylerView.
public class ParentRecyclerView extends RecyclerView {
private GestureDetector mGestureDetector;
public ParentRecyclerView(Context context) {
super(context);
mGestureDetector = new GestureDetector(this.getContext(), new XScrollDetector());
// do the same in other constructors
}
// and override onInterceptTouchEvent
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return super.onInterceptTouchEvent(ev) && mGestureDetector.onTouchEvent(ev);
}
}
Where XScrollDetector is
class XScrollDetector extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return Math.abs(distanceY) < Math.abs(distanceX);
}
}
Thus ParentRecyclerView asks child view (in our case, VerticalRecyclerView) to handle the scroll event. If the child view handles then parent does nothing else parent eventually handles the scroll.
回答2:
setNestedScrollingEnabled(false) on the parent recyclerview
What you could try is setNestedScrollingEnabled(false) on the child RecyclerView, if any. RecyclerView 's nestedscroll-ness is that of a child (that's why it implements NestedScrollingChild).
In the onTouch() of the child recyclerview I disable touch events on the parent recyclerview by called requestdisallowinterceptTouchevent(false)
This should work, but what you should do is requestDisallowInterceptTouchEvent(true), not false. If you subclass RecyclerView, you can override onTouchEvent:
@Override
public boolean onTouchEvent(MotionEvent event) {
if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_UP) {
// ensure we release the disallow request when the finger is lifted
getParent().requestDisallowInterceptTouchEvent(false);
} else {
getParent().requestDisallowInterceptTouchEvent(true);
}
// Call the super class to ensure touch handling
return super.onTouchEvent(event);
}
Or, with a touch listener from outside,
child.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (v.getId() == child.getId()) {
if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_UP) {
// ensure we release the disallow request when the finger is lifted
child.getParent().requestDisallowInterceptTouchEvent(false);
} else {
child.getParent().requestDisallowInterceptTouchEvent(true);
}
}
// Call the super class to ensure touch handling
return super.onTouchEvent(event);
}
});
回答3:
I fixed this issue in a similar project by taking the opposite approach to you (and everyone else here).
Rather than allow the child to tell the parent when to stop looking at events, I let the parent decide when to ignore (based on direction). This approach requires a custom view though which can be a little more work. Below is what I created which would be used as the Outer/Parent view.
public class DirectionalRecyclerView extends RecyclerView {
private static float LOCK_DIRECTION_THRESHOLD; //The slop
private float startX;
private float startY;
private LockDirection mLockDirection = null;
public DirectionalRecyclerView(Context context) {
super(context);
findThreshold(context);
}
public DirectionalRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
findThreshold(context)
}
public DirectionalRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
findThreshold(context);
}
private void findThreshold(Context context) {
//last number is number of dp to move before deciding that's a direction not a tap, you might want to tweak it
LOCK_DIRECTION_THRESHOLD = context.getResources().getDisplayMetrics().density * 12;
}
//events start at the top of the tree and then pass down to
//each child view until they reach where they were initiated
//unless the parent (this) method returns true for this visitor
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
startX = event.getX();
startY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
if (mLockDirection == null) {
float currentX = event.getX();
float currentY = event.getY();
float diffX = Math.abs(currentX - startX);
float diffY = Math.abs(currentY - startY);
if (diffX > LOCK_DIRECTION_THRESHOLD) {
mLockDirection = LockDirection.HORIZONTAL;
} else if (diffY > LOCK_DIRECTION_THRESHOLD) {
mLockDirection = LockDirection.VERTICAL;
}
} else {
//we have locked a direction, check whether we intercept
//the future touches in this event chain
//(returning true steals children's events, otherwise we'll
// just let the event trickle down to the child as usual)
return mLockDirection == LockDirection.HORIZONTAL;
}
break;
case MotionEvent.ACTION_UP:
mLockDirection = null;
break;
}
//dispatch cancel, clicks etc. normally
return super.onInterceptTouchEvent(event);
}
private enum LockDirection {
HORIZONTAL,
VERTICAL
}
}
回答4:
Set the listener to nested RecyclerView
View.OnTouchListener listener = new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_MOVE
) {
v.getParent().requestDisallowInterceptTouchEvent(true);
} else {
v.getParent().requestDisallowInterceptTouchEvent(false);
}
return false;
}
};
mRecyclerView.setOnTouchListener(listener);
回答5:
Now you can try android:nestedScrollingEnabled because Google fixed a crash with usages of nestedScrollingEnabled (Issue 197932)
回答6:
Try this. For my use-case it has worked:
nestedRecyclerView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
return true;
}
});
回答7:
try the below code, hope it will work.
nestedRecyclerView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
// Disallow parent to intercept touch events.
v.getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_UP:
// Allow parent to intercept touch events.
v.getParent().requestDisallowInterceptTouchEvent(false);
break;
}
// Handle inner(child) touch events.
v.onTouchEvent(event);
return true;
}
});
回答8:
Try below code to scroll inner RecyclerView.
innerRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
@Override
public void onTouchEvent(RecyclerView recycler, MotionEvent event) {
// Handle on touch events here
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
// Disallow Parent RecyclerView to intercept touch events.
recycler.getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_UP:
// Allow Parent RecyclerView to intercept touch events.
recycler.getParent().requestDisallowInterceptTouchEvent(false);
break;
}
}
@Override
public boolean onInterceptTouchEvent(RecyclerView recycler, MotionEvent event) {
return false;
}
});
回答9:
IMO, you can try the following inside the Adapter of outer RecyclerView:
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview, parent, false);
RVAdapter2 recyclerViewAdapter2 = new RVAdapter2();
RecyclerView innerRV = (RecyclerView) v.findViewById(R.id.rv2);
// Setup layout manager for items
LinearLayoutManager layoutManager2 = new LinearLayoutManager(parent.getContext());
// Control orientation of the items
layoutManager2.setOrientation(LinearLayoutManager.VERTICAL);
innerRV.setLayoutManager(layoutManager2);
innerRV.setAdapter(recyclerViewAdapter2);
innerRV.setOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
recyclerView.getParent().requestDisallowInterceptTouchEvent(true);
}
});
return new MyViewHolder(v);
}
For API23, you can also try innerRV.setOnScrollChangeListener because setOnScrollListener is deprecated.
UPDATE:
Another option is using addOnScrollListener instead of setOnScrollListener
Hope it helps!
回答10:
You should do this way:
innerRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
@Override
public void onTouchEvent(RecyclerView recycler, MotionEvent event) {
// Handle on touch events here
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
recycler.getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_UP:
recycler.getParent().requestDisallowInterceptTouchEvent(false);
break;
case MotionEvent.ACTION_MOVE:
recycler.getParent().requestDisallowInterceptTouchEvent(true);
break;
}
}
@Override
public boolean onInterceptTouchEvent(RecyclerView recycler, MotionEvent event) {
return false;
}
});
Hope this would help you.
回答11:
Use this code to turn off scroll on recyclerview:
recyclerView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
return true;
}
});
回答12:
The problem exists in Android's implementation of the onInterceptTouchEvent() method for RecyclerView. This blog calls out the problem and fixes it as well - http://nerds.headout.com/fix-horizontal-scrolling-in-your-android-app/. The only difference is that there the parent scrolls vertically and child horizontally. But the solution takes care that it should work for your situation as well.
回答13:
extend a custom layout manager like this
public class CustomLayoutManager extends LinearLayoutManager {
private boolean isScrollEnabled = true;
public CustomGridLayoutManager(Context context) {
super(context);
}
@Override
public boolean canScrollVertically() {
return false;
}
}
Set the layout manager to this "Custom layout Manager"
来源：https://stackoverflow.com/questions/36286391/nested-recyclerview-how-to-prevent-parent-recyclerview-from-getting-scrolled-wh