我试图在我的应用程序中使用RecyclerView，其中包含大量数据，并希望快速滚动它，就像ListView一样。来自this answer的方法适用于ListView，但不适用于RecyclerView。即使我在true布局中快速滚动到RecyclerView，它仍然无效：
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fastScrollEnabled="true"
android:fastScrollAlwaysVisible="true" />
RecyclerView是否支持Android L中的快速滚动？在文档中找不到任何相关内容。
答案 0 :(得分：7)
您在RecyclerView中唯一能找到的就是回收逻辑的基本实现。它与ListView完全相反，它为您提供了最大的自定义性（您可以实现与ListView不同的任何独特布局），但它几乎没有内置它（与ListView不同，它具有快速滚动拇指等众多功能）
如果您想添加类似快速滚动功能的内容，您现在需要自己开发它。
RecyclerView的新 fastScrollEnabled 布尔标志。如果启用，则必须设置fastScrollHorizontalThumbDrawable，fastScrollHorizontalTrackDrawable，fastScrollVerticalThumbDrawable和fastScrollVerticalTrackDrawable。现在可在Support Library 26.0.0
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答案 1 :(得分：3)
我使用https://github.com/woozzu/IndexableListView/tree/master/src/com/woozzu/android/widget
为自己制作了一个并将ListView更改为RecylerView
public class IndexableRecylerView extends RecyclerView implements RecyclerView.OnItemTouchListener{
public IndexScroller mScroller = null;
public IndexableRecylerView(Context context) {
super(context);
init();
}
public IndexableRecylerView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public IndexableRecylerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public void init() {
addOnItemTouchListener(this);
}
public void setFastScrollEnabled(boolean enable) {
if (enable) {
if (mScroller == null)
mScroller = new IndexScroller(getContext(), this);
} else {
if (mScroller != null) {
mScroller.hide();
mScroller = null;
}
}
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
// Overlay index bar
if (mScroller != null)
mScroller.draw(canvas);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (mScroller != null)
mScroller.show();
// Intercept ListView's touch event
if (mScroller != null && mScroller.onTouchEvent(ev))
return true;
return super.onTouchEvent(ev);
}
public void setIndexAdapter(List<String> sectionName, List<Integer> sectionPosition) {
if (mScroller != null)
mScroller.notifyChanges(sectionName, sectionPosition);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (mScroller != null)
mScroller.onSizeChanged(w, h, oldw, oldh);
}
@Override
public void stopScroll()
{
try
{
super.stopScroll();
}
catch( NullPointerException exception )
{
Log.i("RecyclerView", "NPE caught in stopScroll");
}
}
@Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
if (mScroller != null && mScroller.contains(e.getX(), e.getY())) {
mScroller.show();
return true;
}else{
return false;
}
}
@Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) {
}
}
此类在侧面绘制索引器，并允许您滚动它们并滚动recylerview ..
public class IndexScroller {
private float mIndexbarWidth;
private float mIndexbarMargin;
private float mPreviewPadding;
private float mDensity;
private float mScaledDensity;
private float mAlphaRate;
private int mState = STATE_HIDDEN;
private int mListViewWidth;
private int mListViewHeight;
private int mCurrentSection = -1;
private boolean mIsIndexing = false;
private RecyclerView recyclerView = null;
public List<String> mSections = new ArrayList<>();
public List<Integer> mSectionPosition = new ArrayList<>();
private RectF mIndexbarRect;
private static final int STATE_HIDDEN = 0;
private static final int STATE_SHOWING = 1;
private static final int STATE_SHOWN = 2;
private static final int STATE_HIDING = 3;
public IndexScroller(Context context, RecyclerView lv) {
mDensity = context.getResources().getDisplayMetrics().density;
mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
recyclerView = lv;
mIndexbarWidth = 20 * mDensity;
mIndexbarMargin = 10 * mDensity;
mPreviewPadding = 5 * mDensity;
}
public void draw(Canvas canvas) {
if (mState == STATE_HIDDEN)
return;
// mAlphaRate determines the rate of opacity
Paint indexbarPaint = new Paint();
indexbarPaint.setColor(Color.BLACK);
indexbarPaint.setAlpha((int) (64 * mAlphaRate));
indexbarPaint.setAntiAlias(true);
canvas.drawRoundRect(mIndexbarRect, 5 * mDensity, 5 * mDensity, indexbarPaint);
if (mSections != null && mSections.size() > 0) {
// Preview is shown when mCurrentSection is set
if (mCurrentSection >= 0) {
Paint previewPaint = new Paint();
previewPaint.setColor(Color.BLACK);
previewPaint.setAlpha(96);
previewPaint.setAntiAlias(true);
previewPaint.setShadowLayer(3, 0, 0, Color.argb(64, 0, 0, 0));
Paint previewTextPaint = new Paint();
previewTextPaint.setColor(Color.WHITE);
previewTextPaint.setAntiAlias(true);
previewTextPaint.setTextSize(50 * mScaledDensity);
float previewTextWidth = previewTextPaint.measureText(mSections.get(mCurrentSection));
float previewSize = 2 * mPreviewPadding + previewTextPaint.descent() - previewTextPaint.ascent();
RectF previewRect = new RectF((mListViewWidth - previewSize) / 2
, (mListViewHeight - previewSize) / 2
, (mListViewWidth - previewSize) / 2 + previewSize
, (mListViewHeight - previewSize) / 2 + previewSize);
canvas.drawRoundRect(previewRect, 5 * mDensity, 5 * mDensity, previewPaint);
canvas.drawText(mSections.get(mCurrentSection), previewRect.left + (previewSize - previewTextWidth) / 2 - 1
, previewRect.top + mPreviewPadding - previewTextPaint.ascent() + 1, previewTextPaint);
}
Paint indexPaint = new Paint();
indexPaint.setColor(Color.WHITE);
indexPaint.setAlpha((int) (255 * mAlphaRate));
indexPaint.setAntiAlias(true);
indexPaint.setTextSize(12 * mScaledDensity);
float sectionHeight = (mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.size();
float paddingTop = (sectionHeight - (indexPaint.descent() - indexPaint.ascent())) / 2;
for (int i = 0; i < mSections.size(); i++) {
float paddingLeft = (mIndexbarWidth - indexPaint.measureText(mSections.get(i))) / 2;
canvas.drawText(mSections.get(i), mIndexbarRect.left + paddingLeft
, mIndexbarRect.top + mIndexbarMargin + sectionHeight * i + paddingTop - indexPaint.ascent(), indexPaint);
}
}
}
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
// If down event occurs inside index bar region, start indexing
if (mState != STATE_HIDDEN && contains(ev.getX(), ev.getY())) {
setState(STATE_SHOWN);
// It demonstrates that the motion event started from index bar
mIsIndexing = true;
// Determine which section the point is in, and move the list to that section
mCurrentSection = getSectionByPoint(ev.getY());
recyclerView.scrollToPosition(mSectionPosition.get(mCurrentSection));
return true;
}
break;
case MotionEvent.ACTION_MOVE:
if (mIsIndexing) {
// If this event moves inside index bar
if (contains(ev.getX(), ev.getY())) {
// Determine which section the point is in, and move the list to that section
mCurrentSection = getSectionByPoint(ev.getY());
recyclerView.scrollToPosition(mSectionPosition.get(mCurrentSection));
}
return true;
}
break;
case MotionEvent.ACTION_UP:
if (mIsIndexing) {
mIsIndexing = false;
mCurrentSection = -1;
}
if (mState == STATE_SHOWN) {
setState(STATE_HIDING);
}
break;
}
return false;
}
public void onSizeChanged(int w, int h, int oldw, int oldh) {
mListViewWidth = w;
mListViewHeight = h;
mIndexbarRect = new RectF(w - mIndexbarMargin - mIndexbarWidth
, mIndexbarMargin
, w - mIndexbarMargin
, h - mIndexbarMargin);
}
public void show() {
if (mState == STATE_HIDDEN)
setState(STATE_SHOWING);
else if (mState == STATE_HIDING)
setState(STATE_HIDING);
}
public void hide() {
if (mState == STATE_SHOWN)
setState(STATE_HIDING);
}
private void setState(int state) {
if (state < STATE_HIDDEN || state > STATE_HIDING)
return;
mState = state;
switch (mState) {
case STATE_HIDDEN:
// Cancel any fade effect
mHandler.removeMessages(0);
break;
case STATE_SHOWING:
// Start to fade in
mAlphaRate = 0;
fade(0);
break;
case STATE_SHOWN:
// Cancel any fade effect
mHandler.removeMessages(0);
break;
case STATE_HIDING:
// Start to fade out after three seconds
mAlphaRate = 1;
fade(3000);
break;
}
}
public boolean contains(float x, float y) {
// Determine if the point is in index bar region, which includes the right margin of the bar
return (x >= mIndexbarRect.left && y >= mIndexbarRect.top && y <= mIndexbarRect.top + mIndexbarRect.height());
}
private int getSectionByPoint(float y) {
if (mSections == null || mSections.size() == 0)
return 0;
if (y < mIndexbarRect.top + mIndexbarMargin)
return 0;
if (y >= mIndexbarRect.top + mIndexbarRect.height() - mIndexbarMargin)
return mSections.size() - 1;
return (int) ((y - mIndexbarRect.top - mIndexbarMargin) / ((mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.size()));
}
private void fade(long delay) {
mHandler.removeMessages(0);
mHandler.sendEmptyMessageAtTime(0, SystemClock.uptimeMillis() + delay);
}
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (mState) {
case STATE_SHOWING:
// Fade in effect
mAlphaRate += (1 - mAlphaRate) * 0.2;
if (mAlphaRate > 0.9) {
mAlphaRate = 1;
setState(STATE_SHOWN);
}
recyclerView.invalidate();
fade(10);
break;
case STATE_SHOWN:
// If no action, hide automatically
setState(STATE_HIDING);
break;
case STATE_HIDING:
// Fade out effect
mAlphaRate -= mAlphaRate * 0.2;
if (mAlphaRate < 0.1) {
mAlphaRate = 0;
setState(STATE_HIDDEN);
}
recyclerView.invalidate();
fade(10);
break;
}
}
};
public void notifyChanges(List<String> sectionName, List<Integer> sectionPosition) {
// Pre-calculate and pass your section header and position
mSections = sectionNames;
mSectionPosition = sectionPosition;
}}
这只是我修改的快速修复程序来测试它。似乎为我工作，列出了3100项。将项目设置为适配器时，需要计算节标题和位置。在我的情况下，我遍历我的预排序列表并获取每个字符的第一个项目的位置并放入列表并传递给public void notifyChanges（List sectionName，List sectionPosition）。希望它有所帮助。
答案 2 :(得分：2)
我发现的一个更好的解决方案是关于如何为RecyclerView实现自定义快速滚动的好article by Mark Allison中描述的。值得一试。
答案 3 :(得分：1)
有一个library here（“RecyclerViewFastScroller”），可能会有所帮助。
有人在我写的一篇类似的帖子中发表了它，here
答案 4 :(得分：1)
我做了一个library来解决这个问题。现在有很多自定义选项。