是一个仿写百度外卖的app，我在菜品的列表使用了PinnedHeaderListView这个开源库，列表生成已经没问题了(下图，关于流食也是牛肉大葱的bug已经修复，就不换图了)，左边会有一排菜品分类的按钮:"面点"、"流食"、"凉菜"（暂时还没写，假设已经写好了），我想实现像Android电话本一样，比如我点击左边"流食"按钮，那么右边列表上"流食"就会上滚到顶端位置，应该怎么做呢？新手看不太懂源码。
地址是：https://github.com/JimiSmith/PinnedHeaderListView
library中一共只有两个类，
其中PinnedHeaderListVie.java我觉得应该是这个功能相关的
public class PinnedHeaderListView extends ListView implements OnScrollListener {
private OnScrollListener mOnScrollListener;
public static interface PinnedSectionedHeaderAdapter {
public boolean isSectionHeader(int position);
public int getSectionForPosition(int position);
public View getSectionHeaderView(int section, View convertView, ViewGroup parent);
public int getSectionHeaderViewType(int section);
public int getCount();
}
private PinnedSectionedHeaderAdapter mAdapter;
private View mCurrentHeader;
private int mCurrentHeaderViewType = 0;
private float mHeaderOffset;
private boolean mShouldPin = true;
private int mCurrentSection = 0;
private int mWidthMode;
private int mHeightMode;
public PinnedHeaderListView(Context context) {
super(context);
super.setOnScrollListener(this);
}
public PinnedHeaderListView(Context context, AttributeSet attrs) {
super(context, attrs);
super.setOnScrollListener(this);
}
public PinnedHeaderListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
super.setOnScrollListener(this);
}
public void setPinHeaders(boolean shouldPin) {
mShouldPin = shouldPin;
}
@Override
public void setAdapter(ListAdapter adapter) {
mCurrentHeader = null;
mAdapter = (PinnedSectionedHeaderAdapter) adapter;
super.setAdapter(adapter);
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (mOnScrollListener != null) {
mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
}
if (mAdapter == null || mAdapter.getCount() == 0 || !mShouldPin || (firstVisibleItem < getHeaderViewsCount())) {
mCurrentHeader = null;
mHeaderOffset = 0.0f;
for (int i = firstVisibleItem; i < firstVisibleItem + visibleItemCount; i++) {
View header = getChildAt(i);
if (header != null) {
header.setVisibility(VISIBLE);
}
}
return;
}
firstVisibleItem -= getHeaderViewsCount();
int section = mAdapter.getSectionForPosition(firstVisibleItem);
int viewType = mAdapter.getSectionHeaderViewType(section);
mCurrentHeader = getSectionHeaderView(section, mCurrentHeaderViewType != viewType ? null : mCurrentHeader);
ensurePinnedHeaderLayout(mCurrentHeader);
mCurrentHeaderViewType = viewType;
mHeaderOffset = 0.0f;
for (int i = firstVisibleItem; i < firstVisibleItem + visibleItemCount; i++) {
if (mAdapter.isSectionHeader(i)) {
View header = getChildAt(i - firstVisibleItem);
float headerTop = header.getTop();
float pinnedHeaderHeight = mCurrentHeader.getMeasuredHeight();
header.setVisibility(VISIBLE);
if (pinnedHeaderHeight >= headerTop && headerTop > 0) {
mHeaderOffset = headerTop - header.getHeight();
} else if (headerTop <= 0) {
header.setVisibility(INVISIBLE);
}
}
}
invalidate();
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (mOnScrollListener != null) {
mOnScrollListener.onScrollStateChanged(view, scrollState);
}
}
private View getSectionHeaderView(int section, View oldView) {
boolean shouldLayout = section != mCurrentSection || oldView == null;
View view = mAdapter.getSectionHeaderView(section, oldView, this);
if (shouldLayout) {
// a new section, thus a new header. We should lay it out again
ensurePinnedHeaderLayout(view);
mCurrentSection = section;
}
return view;
}
private void ensurePinnedHeaderLayout(View header) {
if (header.isLayoutRequested()) {
int widthSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth(), mWidthMode);
int heightSpec;
ViewGroup.LayoutParams layoutParams = header.getLayoutParams();
if (layoutParams != null && layoutParams.height > 0) {
heightSpec = MeasureSpec.makeMeasureSpec(layoutParams.height, MeasureSpec.EXACTLY);
} else {
heightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
}
header.measure(widthSpec, heightSpec);
header.layout(0, 0, header.getMeasuredWidth(), header.getMeasuredHeight());
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mAdapter == null || !mShouldPin || mCurrentHeader == null)
return;
int saveCount = canvas.save();
canvas.translate(0, mHeaderOffset);
canvas.clipRect(0, 0, getWidth(), mCurrentHeader.getMeasuredHeight()); // needed
// for
// <
// HONEYCOMB
mCurrentHeader.draw(canvas);
canvas.restoreToCount(saveCount);
}
@Override
public void setOnScrollListener(OnScrollListener l) {
mOnScrollListener = l;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mWidthMode = MeasureSpec.getMode(widthMeasureSpec);
mHeightMode = MeasureSpec.getMode(heightMeasureSpec);
}
public void setOnItemClickListener(PinnedHeaderListView.OnItemClickListener listener) {
super.setOnItemClickListener(listener);
}
public static abstract class OnItemClickListener implements AdapterView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int rawPosition, long id) {
SectionedBaseAdapter adapter;
if (adapterView.getAdapter().getClass().equals(HeaderViewListAdapter.class)) {
HeaderViewListAdapter wrapperAdapter = (HeaderViewListAdapter) adapterView.getAdapter();
adapter = (SectionedBaseAdapter) wrapperAdapter.getWrappedAdapter();
} else {
adapter = (SectionedBaseAdapter) adapterView.getAdapter();
}
int section = adapter.getSectionForPosition(rawPosition);
int position = adapter.getPositionInSectionForPosition(rawPosition);
if (position == -1) {
onSectionClick(adapterView, view, section, id);
} else {
onItemClick(adapterView, view, section, position, id);
}
}
public abstract void onItemClick(AdapterView<?> adapterView, View view, int section, int position, long id);
public abstract void onSectionClick(AdapterView<?> adapterView, View view, int section, long id);
}
}
基本算是解决了吧，由于PinnedHeaderListView是继承自ListView的，ListView里有个setSelection方法。
解决办法：
遍历数据源List<Dish>，对应PinnedHeaderListView的结构生成一个ArrayList<Integer> positionList（为了区分，可以当为section时positionList.add(1),当为普通list元素时positionList.add(0)），然后将数据为"1"的位置添加到另一个ArrayList<Integer> sectionPositions中，在菜品列表的onClick()事件调用(你的ListView名称).setSelection(sectionPositions.get(i))。
滑动的动画效果没有实现，这方面还不太了解。