解决RecyclerView无法onItemClick问题的两种方法

public static class ViewHolder extends RecyclerView.ViewHolder { 
public ViewHolder(View itemView) { 
super(itemView); 
itemView.setOnClickListener(new OnClickListener() { 
@Override 
public void onClick(View v) { 
Log.e("jwzhangjie", "当前点击的位置："+getPosition()); 
} 
}); 
} 
} 

/** 
* Interface definition for a callback to be invoked when an item in this 
* RecyclerView.Adapter has been clicked. 
*/ 
public interface OnItemClickListener { 
/** 
* Callback method to be invoked when an item in this RecyclerView.Adapter has 
* been clicked. 
* <p> 
* Implementers can call getPosition(position) if they need 
* to access the data associated with the selected item. 
* 
* @param view The view within the RecyclerView.Adapter that was clicked (this 
* will be a view provided by the adapter) 
* @param position The position of the view in the adapter. 
*/ 
void onItemClick(View view, int position); 
} 
public static OnItemClickListener mOnItemClickListener = null; 
/** 
* Register a callback to be invoked when an item in this AdapterView has 
* been clicked. 
* 
* @param listener The callback that will be invoked. 
*/ 
public void setOnItemClickListener(OnItemClickListener listener) { 
mOnItemClickListener = listener; 
} 
/** 
* @return The callback to be invoked with an item in this AdapterView has 
* been clicked, or null id no callback has been set. 
*/ 
public final OnItemClickListener getOnItemClickListener() { 
return mOnItemClickListener; 
} 

public static abstract class ViewHolder implements OnClickListener{ 
public final View itemView; 
int mPosition = NO_POSITION; 
int mOldPosition = NO_POSITION; 
long mItemId = NO_ID; 
int mItemViewType = INVALID_TYPE; 
/** 
* This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType 
* are all valid. 
*/ 
static final int FLAG_BOUND = 1 << 0; 
/** 
* The data this ViewHolder's view reflects is stale and needs to be rebound 
* by the adapter. mPosition and mItemId are consistent. 
*/ 
static final int FLAG_UPDATE = 1 << 1; 
/** 
* This ViewHolder's data is invalid. The identity implied by mPosition and mItemId 
* are not to be trusted and may no longer match the item view type. 
* This ViewHolder must be fully rebound to different data. 
*/ 
static final int FLAG_INVALID = 1 << 2; 
/** 
* This ViewHolder points at data that represents an item previously removed from the 
* data set. Its view may still be used for things like outgoing animations. 
*/ 
static final int FLAG_REMOVED = 1 << 3; 
/** 
* This ViewHolder should not be recycled. This flag is set via setIsRecyclable() 
* and is intended to keep views around during animations. 
*/ 
static final int FLAG_NOT_RECYCLABLE = 1 << 4; 
private int mFlags; 
private int mIsRecyclableCount = 0; 
// If non-null, view is currently considered scrap and may be reused for other data by the 
// scrap container. 
private Recycler mScrapContainer = null; 
@Override 
public void onClick(View v) { 
if (mOnItemClickListener != null) { 
mOnItemClickListener.onItemClick(itemView, getPosition()); 
} 
} 
public ViewHolder(View itemView) { 
if (itemView == null) { 
throw new IllegalArgumentException("itemView may not be null"); 
} 
this.itemView = itemView; 
this.itemView.setOnClickListener(this); 
} 
void offsetPosition(int offset) { 
if (mOldPosition == NO_POSITION) { 
mOldPosition = mPosition; 
} 
mPosition += offset; 
} 
void clearOldPosition() { 
mOldPosition = NO_POSITION; 
} 
public final int getPosition() { 
return mOldPosition == NO_POSITION ? mPosition : mOldPosition; 
} 
public final long getItemId() { 
return mItemId; 
} 
public final int getItemViewType() { 
return mItemViewType; 
} 
boolean isScrap() { 
return mScrapContainer != null; 
} 
void unScrap() { 
mScrapContainer.unscrapView(this); 
mScrapContainer = null; 
} 
void setScrapContainer(Recycler recycler) { 
mScrapContainer = recycler; 
} 
boolean isInvalid() { 
return (mFlags & FLAG_INVALID) != 0; 
} 
boolean needsUpdate() { 
return (mFlags & FLAG_UPDATE) != 0; 
} 
boolean isBound() { 
return (mFlags & FLAG_BOUND) != 0; 
} 
boolean isRemoved() { 
return (mFlags & FLAG_REMOVED) != 0; 
} 
void setFlags(int flags, int mask) { 
mFlags = (mFlags & ~mask) | (flags & mask); 
} 
void addFlags(int flags) { 
mFlags |= flags; 
} 
void clearFlagsForSharedPool() { 
mFlags = 0; 
} 
@Override 
public String toString() { 
final StringBuilder sb = new StringBuilder("ViewHolder{" + 
Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId); 
if (isScrap()) sb.append(" scrap"); 
if (isInvalid()) sb.append(" invalid"); 
if (!isBound()) sb.append(" unbound"); 
if (needsUpdate()) sb.append(" update"); 
if (isRemoved()) sb.append(" removed"); 
sb.append("}"); 
return sb.toString(); 
} 

cashAccountList.setOnItemClickListener(new OnItemClickListener() { 
@Override 
public void onItemClick(View view, int position) { 
AppLog.e("position： "+position); 
} 
}); 

/* 
* Copyright (C) 2013 The Android Open Source Project 
* 
* Licensed under the Apache License, Version 2.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
* http://www.apache.org/licenses/LICENSE-2.0 
* 
* Unless required by applicable law or agreed to in writing, software 
* distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
* limitations under the License. 
*/ 
package android.support.v7.widget; 
import android.content.Context; 
import android.database.Observable; 
import android.graphics.Canvas; 
import android.graphics.PointF; 
import android.graphics.Rect; 
import android.os.Build; 
import android.os.Parcel; 
import android.os.Parcelable; 
import android.support.annotation.Nullable; 
import android.support.v4.util.ArrayMap; 
import android.support.v4.util.Pools; 
import android.support.v4.view.MotionEventCompat; 
import android.support.v4.view.VelocityTrackerCompat; 
import android.support.v4.view.ViewCompat; 
import android.support.v4.widget.EdgeEffectCompat; 
import android.support.v4.widget.ScrollerCompat; 
import android.util.AttributeSet; 
import android.util.Log; 
import android.util.SparseArray; 
import android.util.SparseIntArray; 
import android.view.FocusFinder; 
import android.view.MotionEvent; 
import android.view.VelocityTracker; 
import android.view.View; 
import android.view.ViewConfiguration; 
import android.view.ViewGroup; 
import android.view.ViewParent; 
import android.view.animation.Interpolator; 
import java.util.ArrayList; 
import java.util.Collections; 
import java.util.List; 
/** 
* A flexible view for providing a limited window into a large data set. 
* 
* <h3>Glossary of terms:</h3> 
* 
* <ul> 
* <li><em>Adapter:</em> A subclass of {@link Adapter} responsible for providing views 
* that represent items in a data set.</li> 
* <li><em>Position:</em> The position of a data item within an <em>Adapter</em>.</li> 
* <li><em>Index:</em> The index of an attached child view as used in a call to 
* {@link ViewGroup#getChildAt}. Contrast with <em>Position.</em></li> 
* <li><em>Binding:</em> The process of preparing a child view to display data corresponding 
* to a <em>position</em> within the adapter.</li> 
* <li><em>Recycle (view):</em> A view previously used to display data for a specific adapter 
* position may be placed in a cache for later reuse to display the same type of data again 
* later. This can drastically improve performance by skipping initial layout inflation 
* or construction.</li> 
* <li><em>Scrap (view):</em> A child view that has entered into a temporarily detached 
* state during layout. Scrap views may be reused without becoming fully detached 
* from the parent RecyclerView, either unmodified if no rebinding is required or modified 
* by the adapter if the view was considered <em>dirty</em>.</li> 
* <li><em>Dirty (view):</em> A child view that must be rebound by the adapter before 
* being displayed.</li> 
* </ul> 
*/ 
public class RecyclerView extends ViewGroup { 
private static final String TAG = "RecyclerView"; 
private static final boolean DEBUG = false; 
private static final boolean ENABLE_PREDICTIVE_ANIMATIONS = false; 
private static final boolean DISPATCH_TEMP_DETACH = false; 
public static final int HORIZONTAL = 0; 
public static final int VERTICAL = 1; 
public static final int NO_POSITION = -1; 
public static final long NO_ID = -1; 
public static final int INVALID_TYPE = -1; 
private static final int MAX_SCROLL_DURATION = 2000; 
private final RecyclerViewDataObserver mObserver = new RecyclerViewDataObserver(); 
private final Recycler mRecycler = new Recycler(); 
private SavedState mPendingSavedState; 
/** 
* Note: this Runnable is only ever posted if: 
* 1) We've been through first layout 
* 2) We know we have a fixed size (mHasFixedSize) 
* 3) We're attached 
*/ 
private final Runnable mUpdateChildViewsRunnable = new Runnable() { 
public void run() { 
if (mPendingUpdates.isEmpty()) { 
return; 
} 
eatRequestLayout(); 
updateChildViews(); 
resumeRequestLayout(true); 
} 
}; 
private final Rect mTempRect = new Rect(); 
private final ArrayList<UpdateOp> mPendingUpdates = new ArrayList<UpdateOp>(); 
private final ArrayList<UpdateOp> mPendingLayoutUpdates = new ArrayList<UpdateOp>(); 
private Pools.Pool<UpdateOp> mUpdateOpPool = new Pools.SimplePool<UpdateOp>(UpdateOp.POOL_SIZE); 
private Adapter mAdapter; 
private LayoutManager mLayout; 
private RecyclerListener mRecyclerListener; 
private final ArrayList<ItemDecoration> mItemDecorations = new ArrayList<ItemDecoration>(); 
private final ArrayList<OnItemTouchListener> mOnItemTouchListeners = 
new ArrayList<OnItemTouchListener>(); 
private OnItemTouchListener mActiveOnItemTouchListener; 
private boolean mIsAttached; 
private boolean mHasFixedSize; 
private boolean mFirstLayoutComplete; 
private boolean mEatRequestLayout; 
private boolean mLayoutRequestEaten; 
private boolean mAdapterUpdateDuringMeasure; 
private final boolean mPostUpdatesOnAnimation; 
private EdgeEffectCompat mLeftGlow, mTopGlow, mRightGlow, mBottomGlow; 
ItemAnimator mItemAnimator = new DefaultItemAnimator(); 
private static final int INVALID_POINTER = -1; 
/** 
* The RecyclerView is not currently scrolling. 
* @see #getScrollState() 
*/ 
public static final int SCROLL_STATE_IDLE = 0; 
/** 
* The RecyclerView is currently being dragged by outside input such as user touch input. 
* @see #getScrollState() 
*/ 
public static final int SCROLL_STATE_DRAGGING = 1; 
/** 
* The RecyclerView is currently animating to a final position while not under 
* outside control. 
* @see #getScrollState() 
*/ 
public static final int SCROLL_STATE_SETTLING = 2; 
// Touch/scrolling handling 
private int mScrollState = SCROLL_STATE_IDLE; 
private int mScrollPointerId = INVALID_POINTER; 
private VelocityTracker mVelocityTracker; 
private int mInitialTouchX; 
private int mInitialTouchY; 
private int mLastTouchX; 
private int mLastTouchY; 
private final int mTouchSlop; 
private final int mMinFlingVelocity; 
private final int mMaxFlingVelocity; 
private final ViewFlinger mViewFlinger = new ViewFlinger(); 
private final State mState = new State(); 
private OnScrollListener mScrollListener; 
// For use in item animations 
boolean mItemsAddedOrRemoved = false; 
boolean mItemsChanged = false; 
int mAnimatingViewIndex = -1; 
int mNumAnimatingViews = 0; 
boolean mInPreLayout = false; 
private ItemAnimator.ItemAnimatorListener mItemAnimatorListener = 
new ItemAnimatorRestoreListener(); 
private boolean mPostedAnimatorRunner = false; 
private Runnable mItemAnimatorRunner = new Runnable() { 
@Override 
public void run() { 
if (mItemAnimator != null) { 
mItemAnimator.runPendingAnimations(); 
} 
mPostedAnimatorRunner = false; 
} 
}; 
private static final Interpolator sQuinticInterpolator = new Interpolator() { 
public float getInterpolation(float t) { 
t -= 1.0f; 
return t * t * t * t * t + 1.0f; 
} 
}; 
public RecyclerView(Context context) { 
this(context, null); 
} 
public RecyclerView(Context context, AttributeSet attrs) { 
this(context, attrs, 0); 
} 
public RecyclerView(Context context, AttributeSet attrs, int defStyle) { 
super(context, attrs, defStyle); 
final int version = Build.VERSION.SDK_INT; 
mPostUpdatesOnAnimation = version >= 16; 
final ViewConfiguration vc = ViewConfiguration.get(context); 
mTouchSlop = vc.getScaledTouchSlop(); 
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity(); 
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity(); 
setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER); 
mItemAnimator.setListener(mItemAnimatorListener); 
} 
/** 
* RecyclerView can perform several optimizations if it can know in advance that changes in 
* adapter content cannot change the size of the RecyclerView itself. 
* If your use of RecyclerView falls into this category, set this to true. 
* 
* @param hasFixedSize true if adapter changes cannot affect the size of the RecyclerView. 
*/ 
public void setHasFixedSize(boolean hasFixedSize) { 
mHasFixedSize = hasFixedSize; 
} 
/** 
* @return true if the app has specified that changes in adapter content cannot change 
* the size of the RecyclerView itself. 
*/ 
public boolean hasFixedSize() { 
return mHasFixedSize; 
} 
/** 
* Set a new adapter to provide child views on demand. 
* 
* @param adapter The new adapter to set, or null to set no adapter. 
*/ 
public void setAdapter(Adapter adapter) { 
if (mAdapter != null) { 
mAdapter.unregisterAdapterDataObserver(mObserver); 
} 
// end all running animations 
if (mItemAnimator != null) { 
mItemAnimator.endAnimations(); 
} 
// Since animations are ended, mLayout.children should be equal to recyclerView.children. 
// This may not be true if item animator's end does not work as expected. (e.g. not release 
// children instantly). It is safer to use mLayout's child count. 
if (mLayout != null) { 
mLayout.removeAndRecycleAllViews(mRecycler); 
mLayout.removeAndRecycleScrapInt(mRecycler, true); 
} 
final Adapter oldAdapter = mAdapter; 
mAdapter = adapter; 
if (adapter != null) { 
adapter.registerAdapterDataObserver(mObserver); 
} 
if (mLayout != null) { 
mLayout.onAdapterChanged(oldAdapter, mAdapter); 
} 
mRecycler.onAdapterChanged(oldAdapter, mAdapter); 
mState.mStructureChanged = true; 
markKnownViewsInvalid(); 
requestLayout(); 
} 
/** 
* Retrieves the previously set adapter or null if no adapter is set. 
* 
* @return The previously set adapter 
* @see #setAdapter(Adapter) 
*/ 
public Adapter getAdapter() { 
return mAdapter; 
} 
/** 
* Register a listener that will be notified whenever a child view is recycled. 
* 
* <p>This listener will be called when a LayoutManager or the RecyclerView decides 
* that a child view is no longer needed. If an application associates expensive 
* or heavyweight data with item views, this may be a good place to release 
* or free those resources.</p> 
* 
* @param listener Listener to register, or null to clear 
*/ 
public void setRecyclerListener(RecyclerListener listener) { 
mRecyclerListener = listener; 
} 
/** 
* Set the {@link LayoutManager} that this RecyclerView will use. 
* 
* <p>In contrast to other adapter-backed views such as {@link android.widget.ListView} 
* or {@link android.widget.GridView}, RecyclerView allows client code to provide custom 
* layout arrangements for child views. These arrangements are controlled by the 
* {@link LayoutManager}. A LayoutManager must be provided for RecyclerView to function.</p> 
* 
* <p>Several default strategies are provided for common uses such as lists and grids.</p> 
* 
* @param layout LayoutManager to use 
*/ 
public void setLayoutManager(LayoutManager layout) { 
if (layout == mLayout) { 
return; 
} 
mRecycler.clear(); 
removeAllViews(); 
if (mLayout != null) { 
if (mIsAttached) { 
mLayout.onDetachedFromWindow(this); 
} 
mLayout.mRecyclerView = null; 
} 
mLayout = layout; 
if (layout != null) { 
if (layout.mRecyclerView != null) { 
throw new IllegalArgumentException("LayoutManager " + layout + 
" is already attached to a RecyclerView: " + layout.mRecyclerView); 
} 
layout.mRecyclerView = this; 
if (mIsAttached) { 
mLayout.onAttachedToWindow(this); 
} 
} 
requestLayout(); 
} 
@Override 
protected Parcelable onSaveInstanceState() { 
SavedState state = new SavedState(super.onSaveInstanceState()); 
if (mPendingSavedState != null) { 
state.copyFrom(mPendingSavedState); 
} else if (mLayout != null) { 
state.mLayoutState = mLayout.onSaveInstanceState(); 
} else { 
state.mLayoutState = null; 
} 
return state; 
} 
@Override 
protected void onRestoreInstanceState(Parcelable state) { 
mPendingSavedState = (SavedState) state; 
super.onRestoreInstanceState(mPendingSavedState.getSuperState()); 
if (mLayout != null && mPendingSavedState.mLayoutState != null) { 
mLayout.onRestoreInstanceState(mPendingSavedState.mLayoutState); 
} 
} 
/** 
* Adds a view to the animatingViews list. 
* mAnimatingViews holds the child views that are currently being kept around 
* purely for the purpose of being animated out of view. They are drawn as a regular 
* part of the child list of the RecyclerView, but they are invisible to the LayoutManager 
* as they are managed separately from the regular child views. 
* @param view The view to be removed 
*/ 
private void addAnimatingView(View view) { 
boolean alreadyAdded = false; 
if (mNumAnimatingViews > 0) { 
for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) { 
if (getChildAt(i) == view) { 
alreadyAdded = true; 
break; 
} 
} 
} 
if (!alreadyAdded) { 
if (mNumAnimatingViews == 0) { 
mAnimatingViewIndex = getChildCount(); 
} 
++mNumAnimatingViews; 
addView(view); 
} 
mRecycler.unscrapView(getChildViewHolder(view)); 
} 
/** 
* Removes a view from the animatingViews list. 
* @param view The view to be removed 
* @see #addAnimatingView(View) 
*/ 
private void removeAnimatingView(View view) { 
if (mNumAnimatingViews > 0) { 
for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) { 
if (getChildAt(i) == view) { 
removeViewAt(i); 
--mNumAnimatingViews; 
if (mNumAnimatingViews == 0) { 
mAnimatingViewIndex = -1; 
} 
mRecycler.recycleView(view); 
return; 
} 
} 
} 
} 
private View getAnimatingView(int position, int type) { 
if (mNumAnimatingViews > 0) { 
for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) { 
final View view = getChildAt(i); 
ViewHolder holder = getChildViewHolder(view); 
if (holder.getPosition() == position && 
( type == INVALID_TYPE || holder.getItemViewType() == type)) { 
return view; 
} 
} 
} 
return null; 
} 
/** 
* Return the {@link LayoutManager} currently responsible for 
* layout policy for this RecyclerView. 
* 
* @return The currently bound LayoutManager 
*/ 
public LayoutManager getLayoutManager() { 
return mLayout; 
} 
/** 
* Retrieve this RecyclerView's {@link RecycledViewPool}. This method will never return null; 
* if no pool is set for this view a new one will be created. See 
* {@link #setRecycledViewPool(RecycledViewPool) setRecycledViewPool} for more information. 
* 
* @return The pool used to store recycled item views for reuse. 
* @see #setRecycledViewPool(RecycledViewPool) 
*/ 
public RecycledViewPool getRecycledViewPool() { 
return mRecycler.getRecycledViewPool(); 
} 
/** 
* Recycled view pools allow multiple RecyclerViews to share a common pool of scrap views. 
* This can be useful if you have multiple RecyclerViews with adapters that use the same 
* view types, for example if you have several data sets with the same kinds of item views 
* displayed by a {@link android.support.v4.view.ViewPager ViewPager}. 
* 
* @param pool Pool to set. If this parameter is null a new pool will be created and used. 
*/ 
public void setRecycledViewPool(RecycledViewPool pool) { 
mRecycler.setRecycledViewPool(pool); 
} 
/** 
* Set the number of offscreen views to retain before adding them to the potentially shared 
* {@link #getRecycledViewPool() recycled view pool}. 
* 
* <p>The offscreen view cache stays aware of changes in the attached adapter, allowing 
* a LayoutManager to reuse those views unmodified without needing to return to the adapter 
* to rebind them.</p> 
* 
* @param size Number of views to cache offscreen before returning them to the general 
* recycled view pool 
*/ 
public void setItemViewCacheSize(int size) { 
mRecycler.setViewCacheSize(size); 
} 
/** 
* Return the current scrolling state of the RecyclerView. 
* 
* @return {@link #SCROLL_STATE_IDLE}, {@link #SCROLL_STATE_DRAGGING} or 
* {@link #SCROLL_STATE_SETTLING} 
*/ 
public int getScrollState() { 
return mScrollState; 
} 
private void setScrollState(int state) { 
if (state == mScrollState) { 
return; 
} 
mScrollState = state; 
if (state != SCROLL_STATE_SETTLING) { 
stopScroll(); 
} 
if (mScrollListener != null) { 
mScrollListener.onScrollStateChanged(state); 
} 
} 
/** 
* Add an {@link ItemDecoration} to this RecyclerView. Item decorations can 
* affect both measurement and drawing of individual item views. 
* 
* <p>Item decorations are ordered. Decorations placed earlier in the list will 
* be run/queried/drawn first for their effects on item views. Padding added to views 
* will be nested; a padding added by an earlier decoration will mean further 
* item decorations in the list will be asked to draw/pad within the previous decoration's 
* given area.</p> 
* 
* @param decor Decoration to add 
* @param index Position in the decoration chain to insert this decoration at. If this value 
* is negative the decoration will be added at the end. 
*/ 
public void addItemDecoration(ItemDecoration decor, int index) { 
if (mItemDecorations.isEmpty()) { 
setWillNotDraw(false); 
} 
if (index < 0) { 
mItemDecorations.add(decor); 
} else { 
mItemDecorations.add(index, decor); 
} 
markItemDecorInsetsDirty(); 
requestLayout(); 
} 
/** 
* Add an {@link ItemDecoration} to this RecyclerView. Item decorations can 
* affect both measurement and drawing of individual item views. 
* 
* <p>Item decorations are ordered. Decorations placed earlier in the list will 
* be run/queried/drawn first for their effects on item views. Padding added to views 
* will be nested; a padding added by an earlier decoration will mean further 
* item decorations in the list will be asked to draw/pad within the previous decoration's 
* given area.</p> 
* 
* @param decor Decoration to add 
*/ 
public void addItemDecoration(ItemDecoration decor) { 
addItemDecoration(decor, -1); 
} 
/** 
* Remove an {@link ItemDecoration} from this RecyclerView. 
* 
* <p>The given decoration will no longer impact the measurement and drawing of 
* item views.</p> 
* 
* @param decor Decoration to remove 
* @see #addItemDecoration(ItemDecoration) 
*/ 
public void removeItemDecoration(ItemDecoration decor) { 
mItemDecorations.remove(decor); 
if (mItemDecorations.isEmpty()) { 
setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER); 
} 
markItemDecorInsetsDirty(); 
requestLayout(); 
} 
/** 
* Set a listener that will be notified of any changes in scroll state or position. 
* 
* @param listener Listener to set or null to clear 
*/ 
public void setOnScrollListener(OnScrollListener listener) { 
mScrollListener = listener; 
} 
/** 
* Convenience method to scroll to a certain position. 
* 
* RecyclerView does not implement scrolling logic, rather forwards the call to 
* {@link android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)} 
* @param position Scroll to this adapter position 
* @see android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int) 
*/ 
public void scrollToPosition(int position) { 
stopScroll(); 
mLayout.scrollToPosition(position); 
awakenScrollBars(); 
} 
/** 
* Starts a smooth scroll to an adapter position. 
* <p> 
* To support smooth scrolling, you must override 
* {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} and create a 
* {@link SmoothScroller}. 
* <p> 
* {@link LayoutManager} is responsible for creating the actual scroll action. If you want to 
* provide a custom smooth scroll logic, override 
* {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} in your 
* LayoutManager. 
* 
* @param position The adapter position to scroll to 
* @see LayoutManager#smoothScrollToPosition(RecyclerView, State, int) 
*/ 
public void smoothScrollToPosition(int position) { 
mLayout.smoothScrollToPosition(this, mState, position); 
} 
@Override 
public void scrollTo(int x, int y) { 
throw new UnsupportedOperationException( 
"RecyclerView does not support scrolling to an absolute position."); 
} 
@Override 
public void scrollBy(int x, int y) { 
if (mLayout == null) { 
throw new IllegalStateException("Cannot scroll without a LayoutManager set. " + 
"Call setLayoutManager with a non-null argument."); 
} 
final boolean canScrollHorizontal = mLayout.canScrollHorizontally(); 
final boolean canScrollVertical = mLayout.canScrollVertically(); 
if (canScrollHorizontal || canScrollVertical) { 
scrollByInternal(canScrollHorizontal ? x : 0, canScrollVertical ? y : 0); 
} 
} 
/** 
* Helper method reflect data changes to the state. 
* <p> 
* Adapter changes during a scroll may trigger a crash because scroll assumes no data change 
* but data actually changed. 
* <p> 
* This method consumes all deferred changes to avoid that case. 
* <p> 
* This also ends all pending animations. It will be changed once we can support 
* animations during scroll. 
*/ 
private void consumePendingUpdateOperations() { 
if (mItemAnimator != null) { 
mItemAnimator.endAnimations(); 
} 
if (mPendingUpdates.size() > 0) { 
mUpdateChildViewsRunnable.run(); 
} 
} 
/** 
* Does not perform bounds checking. Used by internal methods that have already validated input. 
*/ 
void scrollByInternal(int x, int y) { 
int overscrollX = 0, overscrollY = 0; 
consumePendingUpdateOperations(); 
if (mAdapter != null) { 
eatRequestLayout(); 
if (x != 0) { 
final int hresult = mLayout.scrollHorizontallyBy(x, mRecycler, mState); 
overscrollX = x - hresult; 
} 
if (y != 0) { 
final int vresult = mLayout.scrollVerticallyBy(y, mRecycler, mState); 
overscrollY = y - vresult; 
} 
resumeRequestLayout(false); 
} 
if (!mItemDecorations.isEmpty()) { 
invalidate(); 
} 
if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) { 
pullGlows(overscrollX, overscrollY); 
} 
if (mScrollListener != null && (x != 0 || y != 0)) { 
mScrollListener.onScrolled(x, y); 
} 
if (!awakenScrollBars()) { 
invalidate(); 
} 
} 
/** 
* <p>Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal 
* range. This value is used to compute the length of the thumb within the scrollbar's track. 
* </p> 
* 
* <p>The range is expressed in arbitrary units that must be the same as the units used by 
* {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollExtent()}.</p> 
* 
* <p>Default implementation returns 0.</p> 
* 
* <p>If you want to support scroll bars, override 
* {@link RecyclerView.LayoutManager#computeHorizontalScrollOffset(RecyclerView.State)} in your 
* LayoutManager. </p> 
* 
* @return The horizontal offset of the scrollbar's thumb 
* @see android.support.v7.widget.RecyclerView.LayoutManager#computeHorizontalScrollOffset 
* (RecyclerView.Adapter) 
*/ 
@Override 
protected int computeHorizontalScrollOffset() { 
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollOffset(mState) 
: 0; 
} 
/** 
* <p>Compute the horizontal extent of the horizontal scrollbar's thumb within the 
* horizontal range. This value is used to compute the length of the thumb within the 
* scrollbar's track.</p> 
* 
* <p>The range is expressed in arbitrary units that must be the same as the units used by 
* {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollOffset()}.</p> 
* 
* <p>Default implementation returns 0.</p> 
* 
* <p>If you want to support scroll bars, override 
* {@link RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)} in your 
* LayoutManager.</p> 
* 
* @return The horizontal extent of the scrollbar's thumb 
* @see RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State) 
*/ 
@Override 
protected int computeHorizontalScrollExtent() { 
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollExtent(mState) : 0; 
} 
/** 
* <p>Compute the horizontal range that the horizontal scrollbar represents.</p> 
* 
* <p>The range is expressed in arbitrary units that must be the same as the units used by 
* {@link #computeHorizontalScrollExtent()} and {@link #computeHorizontalScrollOffset()}.</p> 
* 
* <p>Default implementation returns 0.</p> 
* 
* <p>If you want to support scroll bars, override 
* {@link RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)} in your 
* LayoutManager.</p> 
* 
* @return The total horizontal range represented by the vertical scrollbar 
* @see RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State) 
*/ 
@Override 
protected int computeHorizontalScrollRange() { 
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollRange(mState) : 0; 
} 
/** 
* <p>Compute the vertical offset of the vertical scrollbar's thumb within the vertical range. 
* This value is used to compute the length of the thumb within the scrollbar's track. </p> 
* 
* <p>The range is expressed in arbitrary units that must be the same as the units used by 
* {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollExtent()}.</p> 
* 
* <p>Default implementation returns 0.</p> 
* 
* <p>If you want to support scroll bars, override 
* {@link RecyclerView.LayoutManager#computeVerticalScrollOffset(RecyclerView.State)} in your 
* LayoutManager.</p> 
* 
* @return The vertical offset of the scrollbar's thumb 
* @see android.support.v7.widget.RecyclerView.LayoutManager#computeVerticalScrollOffset 
* (RecyclerView.Adapter) 
*/ 
@Override 
protected int computeVerticalScrollOffset() { 
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollOffset(mState) : 0; 
} 
/** 
* <p>Compute the vertical extent of the vertical scrollbar's thumb within the vertical range. 
* This value is used to compute the length of the thumb within the scrollbar's track.</p> 
* 
* <p>The range is expressed in arbitrary units that must be the same as the units used by 
* {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollOffset()}.</p> 
* 
* <p>Default implementation returns 0.</p> 
* 
* <p>If you want to support scroll bars, override 
* {@link RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)} in your 
* LayoutManager.</p> 
* 
* @return The vertical extent of the scrollbar's thumb 
* @see RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State) 
*/ 
@Override 
protected int computeVerticalScrollExtent() { 
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollExtent(mState) : 0; 
} 
/** 
* <p>Compute the vertical range that the vertical scrollbar represents.</p> 
* 
* <p>The range is expressed in arbitrary units that must be the same as the units used by 
* {@link #computeVerticalScrollExtent()} and {@link #computeVerticalScrollOffset()}.</p> 
* 
* <p>Default implementation returns 0.</p> 
* 
* <p>If you want to support scroll bars, override 
* {@link RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)} in your 
* LayoutManager.</p> 
* 
* @return The total vertical range represented by the vertical scrollbar 
* @see RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State) 
*/ 
@Override 
protected int computeVerticalScrollRange() { 
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollRange(mState) : 0; 
} 
void eatRequestLayout() { 
if (!mEatRequestLayout) { 
mEatRequestLayout = true; 
mLayoutRequestEaten = false; 
} 
} 
void resumeRequestLayout(boolean performLayoutChildren) { 
if (mEatRequestLayout) { 
if (performLayoutChildren && mLayoutRequestEaten && 
mLayout != null && mAdapter != null) { 
dispatchLayout(); 
} 
mEatRequestLayout = false; 
mLayoutRequestEaten = false; 
} 
} 
/** 
* Animate a scroll by the given amount of pixels along either axis. 
* 
* @param dx Pixels to scroll horizontally 
* @param dy Pixels to scroll vertically 
*/ 
public void smoothScrollBy(int dx, int dy) { 
if (dx != 0 || dy != 0) { 
mViewFlinger.smoothScrollBy(dx, dy); 
} 
} 
/** 
* Begin a standard fling with an initial velocity along each axis in pixels per second. 
* If the velocity given is below the system-defined minimum this method will return false 
* and no fling will occur. 
* 
* @param velocityX Initial horizontal velocity in pixels per second 
* @param velocityY Initial vertical velocity in pixels per second 
* @return true if the fling was started, false if the velocity was too low to fling 
*/ 
public boolean fling(int velocityX, int velocityY) { 
if (Math.abs(velocityX) < mMinFlingVelocity) { 
velocityX = 0; 
} 
if (Math.abs(velocityY) < mMinFlingVelocity) { 
velocityY = 0; 
} 
velocityX = Math.max(-mMaxFlingVelocity, Math.min(velocityX, mMaxFlingVelocity)); 
velocityY = Math.max(-mMaxFlingVelocity, Math.min(velocityY, mMaxFlingVelocity)); 
if (velocityX != 0 || velocityY != 0) { 
mViewFlinger.fling(velocityX, velocityY); 
return true; 
} 
return false; 
} 
/** 
* Stop any current scroll in progress, such as one started by 
* {@link #smoothScrollBy(int, int)}, {@link #fling(int, int)} or a touch-initiated fling. 
*/ 
public void stopScroll() { 
mViewFlinger.stop(); 
mLayout.stopSmoothScroller(); 
} 
/** 
* Apply a pull to relevant overscroll glow effects 
*/ 
private void pullGlows(int overscrollX, int overscrollY) { 
if (overscrollX < 0) { 
if (mLeftGlow == null) { 
mLeftGlow = new EdgeEffectCompat(getContext()); 
mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), 
getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); 
} 
mLeftGlow.onPull(-overscrollX / (float) getWidth()); 
} else if (overscrollX > 0) { 
if (mRightGlow == null) { 
mRightGlow = new EdgeEffectCompat(getContext()); 
mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), 
getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); 
} 
mRightGlow.onPull(overscrollX / (float) getWidth()); 
} 
if (overscrollY < 0) { 
if (mTopGlow == null) { 
mTopGlow = new EdgeEffectCompat(getContext()); 
mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), 
getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); 
} 
mTopGlow.onPull(-overscrollY / (float) getHeight()); 
} else if (overscrollY > 0) { 
if (mBottomGlow == null) { 
mBottomGlow = new EdgeEffectCompat(getContext()); 
mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), 
getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); 
} 
mBottomGlow.onPull(overscrollY / (float) getHeight()); 
} 
if (overscrollX != 0 || overscrollY != 0) { 
ViewCompat.postInvalidateOnAnimation(this); 
} 
} 
private void releaseGlows() { 
boolean needsInvalidate = false; 
if (mLeftGlow != null) needsInvalidate = mLeftGlow.onRelease(); 
if (mTopGlow != null) needsInvalidate |= mTopGlow.onRelease(); 
if (mRightGlow != null) needsInvalidate |= mRightGlow.onRelease(); 
if (mBottomGlow != null) needsInvalidate |= mBottomGlow.onRelease(); 
if (needsInvalidate) { 
ViewCompat.postInvalidateOnAnimation(this); 
} 
} 
void absorbGlows(int velocityX, int velocityY) { 
if (velocityX < 0) { 
if (mLeftGlow == null) { 
mLeftGlow = new EdgeEffectCompat(getContext()); 
mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), 
getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); 
} 
mLeftGlow.onAbsorb(-velocityX); 
} else if (velocityX > 0) { 
if (mRightGlow == null) { 
mRightGlow = new EdgeEffectCompat(getContext()); 
mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), 
getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); 
} 
mRightGlow.onAbsorb(velocityX); 
} 
if (velocityY < 0) { 
if (mTopGlow == null) { 
mTopGlow = new EdgeEffectCompat(getContext()); 
mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), 
getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); 
} 
mTopGlow.onAbsorb(-velocityY); 
} else if (velocityY > 0) { 
if (mBottomGlow == null) { 
mBottomGlow = new EdgeEffectCompat(getContext()); 
mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), 
getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); 
} 
mBottomGlow.onAbsorb(velocityY); 
} 
if (velocityX != 0 || velocityY != 0) { 
ViewCompat.postInvalidateOnAnimation(this); 
} 
} 
// Focus handling 
@Override 
public View focusSearch(View focused, int direction) { 
View result = mLayout.onInterceptFocusSearch(focused, direction); 
if (result != null) { 
return result; 
} 
final FocusFinder ff = FocusFinder.getInstance(); 
result = ff.findNextFocus(this, focused, direction); 
if (result == null && mAdapter != null) { 
eatRequestLayout(); 
result = mLayout.onFocusSearchFailed(focused, direction, mRecycler, mState); 
resumeRequestLayout(false); 
} 
return result != null ? result : super.focusSearch(focused, direction); 
} 
@Override 
public void requestChildFocus(View child, View focused) { 
if (!mLayout.onRequestChildFocus(this, child, focused)) { 
mTempRect.set(0, 0, focused.getWidth(), focused.getHeight()); 
offsetDescendantRectToMyCoords(focused, mTempRect); 
offsetRectIntoDescendantCoords(child, mTempRect); 
requestChildRectangleOnScreen(child, mTempRect, !mFirstLayoutComplete); 
} 
super.requestChildFocus(child, focused); 
} 
@Override 
public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) { 
return mLayout.requestChildRectangleOnScreen(this, child, rect, immediate); 
} 
@Override 
public void addFocusables(ArrayList<View> views, int direction, int focusableMode) { 
if (!mLayout.onAddFocusables(this, views, direction, focusableMode)) { 
super.addFocusables(views, direction, focusableMode); 
} 
} 
@Override 
protected void onAttachedToWindow() { 
super.onAttachedToWindow(); 
mIsAttached = true; 
mFirstLayoutComplete = false; 
if (mLayout != null) { 
mLayout.onAttachedToWindow(this); 
} 
mPostedAnimatorRunner = false; 
} 
@Override 
protected void onDetachedFromWindow() { 
super.onDetachedFromWindow(); 
mFirstLayoutComplete = false; 
stopScroll(); 
// TODO Mark what our target position was if relevant, then we can jump there 
// on reattach. 
mIsAttached = false; 
if (mLayout != null) { 
mLayout.onDetachedFromWindow(this); 
} 
removeCallbacks(mItemAnimatorRunner); 
} 
/** 
* Add an {@link OnItemTouchListener} to intercept touch events before they are dispatched 
* to child views or this view's standard scrolling behavior. 
* 
* <p>Client code may use listeners to implement item manipulation behavior. Once a listener 
* returns true from 
* {@link OnItemTouchListener#onInterceptTouchEvent(RecyclerView, MotionEvent)} its 
* {@link OnItemTouchListener#onTouchEvent(RecyclerView, MotionEvent)} method will be called 
* for each incoming MotionEvent until the end of the gesture.</p> 
* 
* @param listener Listener to add 
*/ 
public void addOnItemTouchListener(OnItemTouchListener listener) { 
mOnItemTouchListeners.add(listener); 
} 
/** 
* Remove an {@link OnItemTouchListener}. It will no longer be able to intercept touch events. 
* 
* @param listener Listener to remove 
*/ 
public void removeOnItemTouchListener(OnItemTouchListener listener) { 
mOnItemTouchListeners.remove(listener); 
if (mActiveOnItemTouchListener == listener) { 
mActiveOnItemTouchListener = null; 
} 
} 
private boolean dispatchOnItemTouchIntercept(MotionEvent e) { 
final int action = e.getAction(); 
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_DOWN) { 
mActiveOnItemTouchListener = null; 
} 
final int listenerCount = mOnItemTouchListeners.size(); 
for (int i = 0; i < listenerCount; i++) { 
final OnItemTouchListener listener = mOnItemTouchListeners.get(i); 
if (listener.onInterceptTouchEvent(this, e) && action != MotionEvent.ACTION_CANCEL) { 
mActiveOnItemTouchListener = listener; 
return true; 
} 
} 
return false; 
} 
private boolean dispatchOnItemTouch(MotionEvent e) { 
final int action = e.getAction(); 
if (mActiveOnItemTouchListener != null) { 
if (action == MotionEvent.ACTION_DOWN) { 
// Stale state from a previous gesture, we're starting a new one. Clear it. 
mActiveOnItemTouchListener = null; 
} else { 
mActiveOnItemTouchListener.onTouchEvent(this, e); 
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { 
// Clean up for the next gesture. 
mActiveOnItemTouchListener = null; 
} 
return true; 
} 
} 
// Listeners will have already received the ACTION_DOWN via dispatchOnItemTouchIntercept 
// as called from onInterceptTouchEvent; skip it. 
if (action != MotionEvent.ACTION_DOWN) { 
final int listenerCount = mOnItemTouchListeners.size(); 
for (int i = 0; i < listenerCount; i++) { 
final OnItemTouchListener listener = mOnItemTouchListeners.get(i); 
if (listener.onInterceptTouchEvent(this, e)) { 
mActiveOnItemTouchListener = listener; 
return true; 
} 
} 
} 
return false; 
} 
@Override 
public boolean onInterceptTouchEvent(MotionEvent e) { 
if (dispatchOnItemTouchIntercept(e)) { 
cancelTouch(); 
return true; 
} 
final boolean canScrollHorizontally = mLayout.canScrollHorizontally(); 
final boolean canScrollVertically = mLayout.canScrollVertically(); 
if (mVelocityTracker == null) { 
mVelocityTracker = VelocityTracker.obtain(); 
} 
mVelocityTracker.addMovement(e); 
final int action = MotionEventCompat.getActionMasked(e); 
final int actionIndex = MotionEventCompat.getActionIndex(e); 
switch (action) { 
case MotionEvent.ACTION_DOWN: 
mScrollPointerId = MotionEventCompat.getPointerId(e, 0); 
mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f); 
mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f); 
if (mScrollState == SCROLL_STATE_SETTLING) { 
getParent().requestDisallowInterceptTouchEvent(true); 
setScrollState(SCROLL_STATE_DRAGGING); 
} 
break; 
case MotionEventCompat.ACTION_POINTER_DOWN: 
mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex); 
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f); 
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f); 
break; 
case MotionEvent.ACTION_MOVE: { 
final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId); 
if (index < 0) { 
Log.e(TAG, "Error processing scroll; pointer index for id " + 
mScrollPointerId + " not found. Did any MotionEvents get skipped?"); 
return false; 
} 
final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f); 
final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f); 
if (mScrollState != SCROLL_STATE_DRAGGING) { 
final int dx = x - mInitialTouchX; 
final int dy = y - mInitialTouchY; 
boolean startScroll = false; 
if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) { 
mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1); 
startScroll = true; 
} 
if (canScrollVertically && Math.abs(dy) > mTouchSlop) { 
mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1); 
startScroll = true; 
} 
if (startScroll) { 
getParent().requestDisallowInterceptTouchEvent(true); 
setScrollState(SCROLL_STATE_DRAGGING); 
} 
} 
} break; 
case MotionEventCompat.ACTION_POINTER_UP: { 
onPointerUp(e); 
} break; 
case MotionEvent.ACTION_UP: { 
mVelocityTracker.clear(); 
} break; 
case MotionEvent.ACTION_CANCEL: { 
cancelTouch(); 
} 
} 
return mScrollState == SCROLL_STATE_DRAGGING; 
} 
@Override 
public boolean onTouchEvent(MotionEvent e) { 
if (dispatchOnItemTouch(e)) { 
cancelTouch(); 
return true; 
} 
final boolean canScrollHorizontally = mLayout.canScrollHorizontally(); 
final boolean canScrollVertically = mLayout.canScrollVertically(); 
if (mVelocityTracker == null) { 
mVelocityTracker = VelocityTracker.obtain(); 
} 
mVelocityTracker.addMovement(e); 
final int action = MotionEventCompat.getActionMasked(e); 
final int actionIndex = MotionEventCompat.getActionIndex(e); 
switch (action) { 
case MotionEvent.ACTION_DOWN: { 
mScrollPointerId = MotionEventCompat.getPointerId(e, 0); 
mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f); 
mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f); 
} break; 
case MotionEventCompat.ACTION_POINTER_DOWN: { 
mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex); 
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f); 
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f); 
} break; 
case MotionEvent.ACTION_MOVE: { 
final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId); 
if (index < 0) { 
Log.e(TAG, "Error processing scroll; pointer index for id " + 
mScrollPointerId + " not found. Did any MotionEvents get skipped?"); 
return false; 
} 
final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f); 
final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f); 
if (mScrollState != SCROLL_STATE_DRAGGING) { 
final int dx = x - mInitialTouchX; 
final int dy = y - mInitialTouchY; 
boolean startScroll = false; 
if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) { 
mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1); 
startScroll = true; 
} 
if (canScrollVertically && Math.abs(dy) > mTouchSlop) { 
mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1); 
startScroll = true; 
} 
if (startScroll) { 
getParent().requestDisallowInterceptTouchEvent(true); 
setScrollState(SCROLL_STATE_DRAGGING); 
} 
} 
if (mScrollState == SCROLL_STATE_DRAGGING) { 
final int dx = x - mLastTouchX; 
final int dy = y - mLastTouchY; 
scrollByInternal(canScrollHorizontally ? -dx : 0, 
canScrollVertically ? -dy : 0); 
} 
mLastTouchX = x; 
mLastTouchY = y; 
} break; 
case MotionEventCompat.ACTION_POINTER_UP: { 
onPointerUp(e); 
} break; 
case MotionEvent.ACTION_UP: { 
mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity); 
final float xvel = canScrollHorizontally ? 
-VelocityTrackerCompat.getXVelocity(mVelocityTracker, mScrollPointerId) : 0; 
final float yvel = canScrollVertically ? 
-VelocityTrackerCompat.getYVelocity(mVelocityTracker, mScrollPointerId) : 0; 
if (!((xvel != 0 || yvel != 0) && fling((int) xvel, (int) yvel))) { 
setScrollState(SCROLL_STATE_IDLE); 
} 
mVelocityTracker.clear(); 
releaseGlows(); 
} break; 
case MotionEvent.ACTION_CANCEL: { 
cancelTouch(); 
} break; 
} 
return true; 
} 
private void cancelTouch() { 
mVelocityTracker.clear(); 
releaseGlows(); 
setScrollState(SCROLL_STATE_IDLE); 
} 
private void onPointerUp(MotionEvent e) { 
final int actionIndex = MotionEventCompat.getActionIndex(e); 
if (MotionEventCompat.getPointerId(e, actionIndex) == mScrollPointerId) { 
// Pick a new pointer to pick up the slack. 
final int newIndex = actionIndex == 0 ? 1 : 0; 
mScrollPointerId = MotionEventCompat.getPointerId(e, newIndex); 
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, newIndex) + 0.5f); 
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, newIndex) + 0.5f); 
} 
} 
@Override 
protected void onMeasure(int widthSpec, int heightSpec) { 
if (mAdapterUpdateDuringMeasure) { 
eatRequestLayout(); 
updateChildViews(); 
mAdapterUpdateDuringMeasure = false; 
resumeRequestLayout(false); 
} 
if (mAdapter != null) { 
mState.mItemCount = mAdapter.getItemCount(); 
} 
mLayout.onMeasure(mRecycler, mState, widthSpec, heightSpec); 
final int widthSize = getMeasuredWidth(); 
final int heightSize = getMeasuredHeight(); 
if (mLeftGlow != null) mLeftGlow.setSize(heightSize, widthSize); 
if (mTopGlow != null) mTopGlow.setSize(widthSize, heightSize); 
if (mRightGlow != null) mRightGlow.setSize(heightSize, widthSize); 
if (mBottomGlow != null) mBottomGlow.setSize(widthSize, heightSize); 
} 
/** 
* Sets the {@link ItemAnimator} that will handle animations involving changes 
* to the items in this RecyclerView. By default, RecyclerView instantiates and 
* uses an instance of {@link DefaultItemAnimator}. Whether item animations are 
* enabled for the RecyclerView depends on the ItemAnimator and whether 
* the LayoutManager {@link LayoutManager#supportsPredictiveItemAnimations() 
* supports item animations}. 
* 
* @param animator The ItemAnimator being set. If null, no animations will occur 
* when changes occur to the items in this RecyclerView. 
*/ 
public void setItemAnimator(ItemAnimator animator) { 
if (mItemAnimator != null) { 
mItemAnimator.setListener(null); 
} 
mItemAnimator = animator; 
if (mItemAnimator != null) { 
mItemAnimator.setListener(mItemAnimatorListener); 
} 
} 
/** 
* Gets the current ItemAnimator for this RecyclerView. A null return value 
* indicates that there is no animator and that item changes will happen without 
* any animations. By default, RecyclerView instantiates and 
* uses an instance of {@link DefaultItemAnimator}. 
* 
* @return ItemAnimator The current ItemAnimator. If null, no animations will occur 
* when changes occur to the items in this RecyclerView. 
*/ 
public ItemAnimator getItemAnimator() { 
return mItemAnimator; 
} 
/** 
* Post a runnable to the next frame to run pending item animations. Only the first such 
* request will be posted, governed by the mPostedAnimatorRunner flag. 
*/ 
private void postAnimationRunner() { 
if (!mPostedAnimatorRunner && mIsAttached) { 
ViewCompat.postOnAnimation(this, mItemAnimatorRunner); 
mPostedAnimatorRunner = true; 
} 
} 
private boolean predictiveItemAnimationsEnabled() { 
return (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations()); 
} 
/** 
* Wrapper around layoutChildren() that handles animating changes caused by layout. 
* Animations work on the assumption that there are five different kinds of items 
* in play: 
* PERSISTENT: items are visible before and after layout 
* REMOVED: items were visible before layout and were removed by the app 
* ADDED: items did not exist before layout and were added by the app 
* DISAPPEARING: items exist in the data set before/after, but changed from 
* visible to non-visible in the process of layout (they were moved off 
* screen as a side-effect of other changes) 
* APPEARING: items exist in the data set before/after, but changed from 
* non-visible to visible in the process of layout (they were moved on 
* screen as a side-effect of other changes) 
* The overall approach figures out what items exist before/after layout and 
* infers one of the five above states for each of the items. Then the animations 
* are set up accordingly: 
* PERSISTENT views are moved ({@link ItemAnimator#animateMove(ViewHolder, int, int, int, int)}) 
* REMOVED views are removed ({@link ItemAnimator#animateRemove(ViewHolder)}) 
* ADDED views are added ({@link ItemAnimator#animateAdd(ViewHolder)}) 
* DISAPPEARING views are moved off screen 
* APPEARING views are moved on screen 
*/ 
void dispatchLayout() { 
if (mAdapter == null) { 
Log.e(TAG, "No adapter attached; skipping layout"); 
return; 
} 
eatRequestLayout(); 
// simple animations are a subset of advanced animations (which will cause a 
// prelayout step) 
boolean animateChangesSimple = mItemAnimator != null && mItemsAddedOrRemoved 
&& !mItemsChanged; 
final boolean animateChangesAdvanced = ENABLE_PREDICTIVE_ANIMATIONS && 
animateChangesSimple && predictiveItemAnimationsEnabled(); 
mItemsAddedOrRemoved = mItemsChanged = false; 
ArrayMap<View, Rect> appearingViewInitialBounds = null; 
mState.mInPreLayout = animateChangesAdvanced; 
mState.mItemCount = mAdapter.getItemCount(); 
if (animateChangesSimple) { 
// Step 0: Find out where all non-removed items are, pre-layout 
mState.mPreLayoutHolderMap.clear(); 
mState.mPostLayoutHolderMap.clear(); 
int count = getChildCount(); 
for (int i = 0; i < count; ++i) { 
final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); 
final View view = holder.itemView; 
mState.mPreLayoutHolderMap.put(holder, new ItemHolderInfo(holder, 
view.getLeft(), view.getTop(), view.getRight(), view.getBottom(), 
holder.mPosition)); 
} 
} 
if (animateChangesAdvanced) { 
// Step 1: run prelayout: This will use the old positions of items. The layout manager 
// is expected to layout everything, even removed items (though not to add removed 
// items back to the container). This gives the pre-layout position of APPEARING views 
// which come into existence as part of the real layout. 
mInPreLayout = true; 
final boolean didStructureChange = mState.mStructureChanged; 
mState.mStructureChanged = false; 
// temporarily disable flag because we are asking for previous layout 
mLayout.onLayoutChildren(mRecycler, mState); 
mState.mStructureChanged = didStructureChange; 
mInPreLayout = false; 
appearingViewInitialBounds = new ArrayMap<View, Rect>(); 
for (int i = 0; i < getChildCount(); ++i) { 
boolean found = false; 
View child = getChildAt(i); 
for (int j = 0; j < mState.mPreLayoutHolderMap.size(); ++j) { 
ViewHolder holder = mState.mPreLayoutHolderMap.keyAt(j); 
if (holder.itemView == child) { 
found = true; 
continue; 
} 
} 
if (!found) { 
appearingViewInitialBounds.put(child, new Rect(child.getLeft(), child.getTop(), 
child.getRight(), child.getBottom())); 
} 
} 
} 
clearOldPositions(); 
dispatchLayoutUpdates(); 
mState.mItemCount = mAdapter.getItemCount(); 
// Step 2: Run layout 
mState.mInPreLayout = false; 
mLayout.onLayoutChildren(mRecycler, mState); 
mState.mStructureChanged = false; 
mPendingSavedState = null; 
// onLayoutChildren may have caused client code to disable item animations; re-check 
animateChangesSimple = animateChangesSimple && mItemAnimator != null; 
if (animateChangesSimple) { 
// Step 3: Find out where things are now, post-layout 
int count = getChildCount(); 
for (int i = 0; i < count; ++i) { 
ViewHolder holder = getChildViewHolderInt(getChildAt(i)); 
final View view = holder.itemView; 
mState.mPostLayoutHolderMap.put(holder, new ItemHolderInfo(holder, 
view.getLeft(), view.getTop(), view.getRight(), view.getBottom(), 
holder.mPosition)); 
} 
// Step 4: Animate DISAPPEARING and REMOVED items 
int preLayoutCount = mState.mPreLayoutHolderMap.size(); 
for (int i = preLayoutCount - 1; i >= 0; i--) { 
ViewHolder itemHolder = mState.mPreLayoutHolderMap.keyAt(i); 
if (!mState.mPostLayoutHolderMap.containsKey(itemHolder)) { 
ItemHolderInfo disappearingItem = mState.mPreLayoutHolderMap.valueAt(i); 
mState.mPreLayoutHolderMap.removeAt(i); 
View disappearingItemView = disappearingItem.holder.itemView; 
removeDetachedView(disappearingItemView, false); 
mRecycler.unscrapView(disappearingItem.holder); 
animateDisappearance(disappearingItem); 
} 
} 
// Step 5: Animate APPEARING and ADDED items 
int postLayoutCount = mState.mPostLayoutHolderMap.size(); 
if (postLayoutCount > 0) { 
for (int i = postLayoutCount - 1; i >= 0; i--) { 
ViewHolder itemHolder = mState.mPostLayoutHolderMap.keyAt(i); 
ItemHolderInfo info = mState.mPostLayoutHolderMap.valueAt(i); 
if ((mState.mPreLayoutHolderMap.isEmpty() || 
!mState.mPreLayoutHolderMap.containsKey(itemHolder))) { 
mState.mPostLayoutHolderMap.removeAt(i); 
Rect initialBounds = (appearingViewInitialBounds != null) ? 
appearingViewInitialBounds.get(itemHolder.itemView) : null; 
animateAppearance(itemHolder, initialBounds, 
info.left, info.top); 
} 
} 
} 
// Step 6: Animate PERSISTENT items 
count = mState.mPostLayoutHolderMap.size(); 
for (int i = 0; i < count; ++i) { 
ViewHolder postHolder = mState.mPostLayoutHolderMap.keyAt(i); 
ItemHolderInfo postInfo = mState.mPostLayoutHolderMap.valueAt(i); 
ItemHolderInfo preInfo = mState.mPreLayoutHolderMap.get(postHolder); 
if (preInfo != null && postInfo != null) { 
if (preInfo.left != postInfo.left || preInfo.top != postInfo.top) { 
postHolder.setIsRecyclable(false); 
if (DEBUG) { 
Log.d(TAG, "PERSISTENT: " + postHolder + 
" with view " + postHolder.itemView); 
} 
if (mItemAnimator.animateMove(postHolder, 
preInfo.left, preInfo.top, postInfo.left, postInfo.top)) { 
postAnimationRunner(); 
} 
} 
} 
} 
} 
resumeRequestLayout(false); 
mLayout.removeAndRecycleScrapInt(mRecycler, !animateChangesAdvanced); 
mState.mPreviousLayoutItemCount = mState.mItemCount; 
mState.mDeletedInvisibleItemCountSincePreviousLayout = 0; 
} 
private void animateAppearance(ViewHolder itemHolder, Rect beforeBounds, int afterLeft, 
int afterTop) { 
View newItemView = itemHolder.itemView; 
if (beforeBounds != null && 
(beforeBounds.left != afterLeft || beforeBounds.top != afterTop)) { 
// slide items in if before/after locations differ 
itemHolder.setIsRecyclable(false); 
if (DEBUG) { 
Log.d(TAG, "APPEARING: " + itemHolder + " with view " + newItemView); 
} 
if (mItemAnimator.animateMove(itemHolder, 
beforeBounds.left, beforeBounds.top, 
afterLeft, afterTop)) { 
postAnimationRunner(); 
} 
} else { 
if (DEBUG) { 
Log.d(TAG, "ADDED: " + itemHolder + " with view " + newItemView); 
} 
itemHolder.setIsRecyclable(false); 
if (mItemAnimator.animateAdd(itemHolder)) { 
postAnimationRunner(); 
} 
} 
} 
private void animateDisappearance(ItemHolderInfo disappearingItem) { 
View disappearingItemView = disappearingItem.holder.itemView; 
addAnimatingView(disappearingItemView); 
int oldLeft = disappearingItem.left; 
int oldTop = disappearingItem.top; 
int newLeft = disappearingItemView.getLeft(); 
int newTop = disappearingItemView.getTop(); 
if (oldLeft != newLeft || oldTop != newTop) { 
disappearingItem.holder.setIsRecyclable(false); 
disappearingItemView.layout(newLeft, newTop, 
newLeft + disappearingItemView.getWidth(), 
newTop + disappearingItemView.getHeight()); 
if (DEBUG) { 
Log.d(TAG, "DISAPPEARING: " + disappearingItem.holder + 
" with view " + disappearingItemView); 
} 
if (mItemAnimator.animateMove(disappearingItem.holder, oldLeft, oldTop, 
newLeft, newTop)) { 
postAnimationRunner(); 
} 
} else { 
if (DEBUG) { 
Log.d(TAG, "REMOVED: " + disappearingItem.holder + 
" with view " + disappearingItemView); 
} 
disappearingItem.holder.setIsRecyclable(false); 
if (mItemAnimator.animateRemove(disappearingItem.holder)) { 
postAnimationRunner(); 
} 
} 
} 
@Override 
protected void onLayout(boolean changed, int l, int t, int r, int b) { 
eatRequestLayout(); 
dispatchLayout(); 
resumeRequestLayout(false); 
mFirstLayoutComplete = true; 
} 
@Override 
public void requestLayout() { 
if (!mEatRequestLayout) { 
super.requestLayout(); 
} else { 
mLayoutRequestEaten = true; 
} 
} 
void markItemDecorInsetsDirty() { 
final int childCount = getChildCount(); 
for (int i = 0; i < childCount; i++) { 
final View child = getChildAt(i); 
((LayoutParams) child.getLayoutParams()).mInsetsDirty = true; 
} 
} 
@Override 
public void draw(Canvas c) { 
super.draw(c); 
final int count = mItemDecorations.size(); 
for (int i = 0; i < count; i++) { 
mItemDecorations.get(i).onDrawOver(c, this); 
} 
boolean needsInvalidate = false; 
if (mLeftGlow != null && !mLeftGlow.isFinished()) { 
final int restore = c.save(); 
c.rotate(270); 
c.translate(-getHeight() + getPaddingTop(), 0); 
needsInvalidate = mLeftGlow != null && mLeftGlow.draw(c); 
c.restoreToCount(restore); 
} 
if (mTopGlow != null && !mTopGlow.isFinished()) { 
c.translate(getPaddingLeft(), getPaddingTop()); 
needsInvalidate |= mTopGlow != null && mTopGlow.draw(c); 
} 
if (mRightGlow != null && !mRightGlow.isFinished()) { 
final int restore = c.save(); 
final int width = getWidth(); 
c.rotate(90); 
c.translate(-getPaddingTop(), -width); 
needsInvalidate |= mRightGlow != null && mRightGlow.draw(c); 
c.restoreToCount(restore); 
} 
if (mBottomGlow != null && !mBottomGlow.isFinished()) { 
final int restore = c.save(); 
c.rotate(180); 
c.translate(-getWidth() + getPaddingLeft(), -getHeight() + getPaddingTop()); 
needsInvalidate |= mBottomGlow != null && mBottomGlow.draw(c); 
c.restoreToCount(restore); 
} 
if (needsInvalidate) { 
ViewCompat.postInvalidateOnAnimation(this); 
} 
} 
@Override 
public void onDraw(Canvas c) { 
super.onDraw(c); 
final int count = mItemDecorations.size(); 
for (int i = 0; i < count; i++) { 
mItemDecorations.get(i).onDraw(c, this); 
} 
} 
@Override 
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { 
return p instanceof LayoutParams && mLayout.checkLayoutParams((LayoutParams) p); 
} 
@Override 
protected ViewGroup.LayoutParams generateDefaultLayoutParams() { 
if (mLayout == null) { 
throw new IllegalStateException("RecyclerView has no LayoutManager"); 
} 
return mLayout.generateDefaultLayoutParams(); 
} 
@Override 
public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) { 
if (mLayout == null) { 
throw new IllegalStateException("RecyclerView has no LayoutManager"); 
} 
return mLayout.generateLayoutParams(getContext(), attrs); 
} 
@Override 
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { 
if (mLayout == null) { 
throw new IllegalStateException("RecyclerView has no LayoutManager"); 
} 
return mLayout.generateLayoutParams(p); 
} 
private int findPositionOffset(int position) { 
int offset = 0; 
int count = mPendingLayoutUpdates.size(); 
for (int i = 0; i < count; ++i) { 
UpdateOp op = mPendingLayoutUpdates.get(i); 
if (op.positionStart <= position) { 
if (op.cmd == UpdateOp.REMOVE) { 
offset -= op.itemCount; 
} else if (op.cmd == UpdateOp.ADD) { 
off