Android - NullPointerException SimpleAdapter - 固定部分ListView？
我创建了ListView pinned，效果很好。但是当我到达ListView崩溃的最新项目时，我会说NullPointerException。
当我到达最新项目时，我需要获得下一个项目。
MainActivity.java：
public class PinnedSectionListActivity extends ListActivity implements OnClickListener {
public static Context context;
public static Context _context;
public static SQLiteDatabase sql;
public Cursor cursor;
public Cursor cursorA;
public boolean flag = false;
public Integer count = 0;
public List<Items> result;
public List<ItemsT> resultT;
static class SimpleAdapter extends ArrayAdapter<Item> implements PinnedSectionListView.PinnedSectionListAdapter {
private List<Items> Results;
private List<ItemsT> ResultsT;
private Integer counts;
private static final int[] COLORS = new int[] {
R.color.green_light, R.color.orange_light,
R.color.blue_light, R.color.red_light };
public SimpleAdapter(Context context,List<Items> MResults,List<ItemsT> MresultT,Integer count , int resource, int textViewResourceId) {
super(context, resource, textViewResourceId);
this.Results = MResults;
this.ResultsT = MresultT;
this.counts = count;
generateDataset(false);
}
public void generateDataset(boolean clear) {
int y = 0;
if (clear) clear();
prepareSections(counts);
int sectionPosition = 0, listPosition = 0;
for (char i=0; i<counts; i++) {
final Items ci = Results.get(i);
Item section = new Item(Item.SECTION, ci.WTitleO);
section.sectionPosition = sectionPosition;
section.listPosition = listPosition++;
onSectionAdded(section, sectionPosition);
add(section);
for (int j=0;j<ci.count;j++) {
final ItemsT xx = ResultsT.get(y);
Item item = new Item(Item.ITEM, xx.WTitleT);
item.sectionPosition = sectionPosition;
item.listPosition = listPosition++;
y++;
add(item);
}
sectionPosition++;
}
}
protected void prepareSections(int sectionsNumber) { }
protected void onSectionAdded(Item section, int sectionPosition) { }
@Override public View getView(int position, View convertView, ViewGroup parent) {
TextView view = (TextView) super.getView(position, convertView, parent);
view.setTextColor(Color.DKGRAY);
view.setTag("" + position);
Item item = getItem(position);
if (item.type == Item.SECTION) {
view.setBackgroundColor(parent.getResources().getColor(COLORS[item.sectionPosition % COLORS.length]));
}
return view;
}
@Override public int getViewTypeCount() {
return 2;
}
@Override public int getItemViewType(int position) {
return getItem(position).type;
}
@Override
public boolean isItemViewTypePinned(int viewType) {
return viewType == Item.SECTION;
}
}
static class Items {
public int conO ;
public String WTitleO;
public int count;
}
static class ItemsT {
public String WTitleT;
}
static class Item {
public static final int ITEM = 0;
public static final int SECTION = 1;
public final int type;
public final String text;
public int sectionPosition;
public int listPosition;
public Item(int type, String text) {
this.type = type;
this.text = text;
}
@Override public String toString() {
return text;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = getApplicationContext();
_context = this;
DB db = new DB(context);
db.CreateFile();
try {
db.CreateandOpenDataBase();
} catch (IOException e) {
e.printStackTrace();
}
sql = db.openDataBase();
test();
}
public void test(){
result = new ArrayList<Items>();
resultT = new ArrayList<ItemsT>();
try {
cursor = sql.rawQuery("SELECT (select count() as number from WebSite_BookPageDB22 as b where b.ParentID = a.ContentID) as count" +
" ,ContentID,Title" +
" FROM WebSite_BookPageDB22 as a" +
" WHERE ArticleID = '" + 61799 + "' AND ParentID = '" + 0 + "'order by PageID ASC LIMIT 5", null);
if (cursor != null) {
if (cursor.moveToFirst()) {
do {
Items ci = new Items();
ci.conO = cursor.getInt(cursor.getColumnIndex("ContentID"));
ci.WTitleO = cursor.getString(cursor.getColumnIndex("Title"));
ci.count = cursor.getInt(cursor.getColumnIndex("count"));
if(flag == false) {
count = cursor.getCount();
flag = true;
}
cursorA = sql.rawQuery("select Title from WebSite_BookPageDB22 where ParentID = '" + ci.conO +"' order by PageID ASC", null);
try {
if (cursorA != null && cursorA.moveToFirst()) {
do {
ItemsT cty = new ItemsT();
cty.WTitleT = cursorA.getString(cursorA.getColumnIndex("Title"));
resultT.add(cty);
} while (cursorA.moveToNext());
}
}catch (Exception e){
Log.i("xxx", "You have an error");
}finally {
if (cursorA != null) {
cursorA.close();
}
}
result.add(ci);
} while (cursor.moveToNext());
}
}
} catch (Exception e) {
} finally {
cursor.close();
}
SimpleAdapter adapt = new SimpleAdapter(_context, result, resultT, count, android.R.layout.simple_list_item_1, android.R.id.text1);
setListAdapter(adapt);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
Item item = (Item) getListView().getAdapter().getItem(position);
if (item != null) {
Toast.makeText(this, "Item " + position + ": " + item.text, Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "Item " + position, Toast.LENGTH_SHORT).show();
}
}
@Override
public void onClick(View v) {
Toast.makeText(this, "Item: " + v.getTag() , Toast.LENGTH_SHORT).show();
}
}
PinnedSectionListView.java：
public class PinnedSectionListView extends ListView {
//-- inner classes
/** List adapter to be implemented for being used with PinnedSectionListView adapter. */
public static interface PinnedSectionListAdapter extends ListAdapter {
/** This method shall return 'true' if views of given type has to be pinned. */
boolean isItemViewTypePinned(int viewType);
}
/** Wrapper class for pinned section view and its position in the list. */
static class PinnedSection {
public View view;
public int position;
public long id;
}
//-- class fields
// fields used for handling touch events
private final Rect mTouchRect = new Rect();
private final PointF mTouchPoint = new PointF();
private int mTouchSlop;
private View mTouchTarget;
private MotionEvent mDownEvent;
// fields used for drawing shadow under a pinned section
private GradientDrawable mShadowDrawable;
private int mSectionsDistanceY;
private int mShadowHeight;
/** Delegating listener, can be null. */
OnScrollListener mDelegateOnScrollListener;
/** Shadow for being recycled, can be null. */
PinnedSection mRecycleSection;
/** shadow instance with a pinned view, can be null. */
PinnedSection mPinnedSection;
/** Pinned view Y-translation. We use it to stick pinned view to the next section. */
int mTranslateY;
/** Scroll listener which does the magic */
private final OnScrollListener mOnScrollListener = new OnScrollListener() {
@Override public void onScrollStateChanged(AbsListView view, int scrollState) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScrollStateChanged(view, scrollState);
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
}
if(firstVisibleItem+visibleItemCount == totalItemCount && totalItemCount!=0)
{
PinnedSectionListActivity xx = new PinnedSectionListActivity();
xx.flag = false;
xx.test();
/*Intent refresh = new Intent(PinnedSectionListActivity._context, PinnedSectionListActivity.class);
PinnedSectionListActivity._context.startActivity(refresh);*/
}
// get expected adapter or fail fast
ListAdapter adapter = getAdapter();
if (adapter == null || visibleItemCount == 0) return; // nothing to do
final boolean isFirstVisibleItemSection =
isItemViewTypePinned(adapter, adapter.getItemViewType(firstVisibleItem));
if (isFirstVisibleItemSection) {
View sectionView = getChildAt(0);
if (sectionView.getTop() == getPaddingTop()) { // view sticks to the top, no need for pinned shadow
destroyPinnedShadow();
} else { // section doesn't stick to the top, make sure we have a pinned shadow
ensureShadowForPosition(firstVisibleItem, firstVisibleItem, visibleItemCount);
}
} else { // section is not at the first visible position
int sectionPosition = findCurrentSectionPosition(firstVisibleItem);
if (sectionPosition > -1) { // we have section position
ensureShadowForPosition(sectionPosition, firstVisibleItem, visibleItemCount);
} else { // there is no section for the first visible item, destroy shadow
destroyPinnedShadow();
}
}
};
};
/** Default change observer. */
private final DataSetObserver mDataSetObserver = new DataSetObserver() {
@Override public void onChanged() {
recreatePinnedShadow();
};
@Override public void onInvalidated() {
recreatePinnedShadow();
}
};
//-- constructors
public PinnedSectionListView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
public PinnedSectionListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
private void initView() {
setOnScrollListener(mOnScrollListener);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
initShadow(true);
}
//-- public API methods
public void setShadowVisible(boolean visible) {
initShadow(visible);
if (mPinnedSection != null) {
View v = mPinnedSection.view;
invalidate(v.getLeft(), v.getTop(), v.getRight(), v.getBottom() + mShadowHeight);
}
}
//-- pinned section drawing methods
public void initShadow(boolean visible) {
if (visible) {
if (mShadowDrawable == null) {
mShadowDrawable = new GradientDrawable(Orientation.TOP_BOTTOM,
new int[] { Color.parseColor("#ffa0a0a0"), Color.parseColor("#50a0a0a0"), Color.parseColor("#00a0a0a0")});
mShadowHeight = (int) (8 * getResources().getDisplayMetrics().density);
}
} else {
if (mShadowDrawable != null) {
mShadowDrawable = null;
mShadowHeight = 0;
}
}
}
/** Create shadow wrapper with a pinned view for a view at given position */
void createPinnedShadow(int position) {
// try to recycle shadow
PinnedSection pinnedShadow = mRecycleSection;
mRecycleSection = null;
// create new shadow, if needed
if (pinnedShadow == null) pinnedShadow = new PinnedSection();
// request new view using recycled view, if such
View pinnedView = getAdapter().getView(position, pinnedShadow.view, PinnedSectionListView.this);
// read layout parameters
LayoutParams layoutParams = (LayoutParams) pinnedView.getLayoutParams();
if (layoutParams == null) {
layoutParams = (LayoutParams) generateDefaultLayoutParams();
pinnedView.setLayoutParams(layoutParams);
}
int heightMode = MeasureSpec.getMode(layoutParams.height);
int heightSize = MeasureSpec.getSize(layoutParams.height);
if (heightMode == MeasureSpec.UNSPECIFIED) heightMode = MeasureSpec.EXACTLY;
int maxHeight = getHeight() - getListPaddingTop() - getListPaddingBottom();
if (heightSize > maxHeight) heightSize = maxHeight;
// measure & layout
int ws = MeasureSpec.makeMeasureSpec(getWidth() - getListPaddingLeft() - getListPaddingRight(), MeasureSpec.EXACTLY);
int hs = MeasureSpec.makeMeasureSpec(heightSize, heightMode);
pinnedView.measure(ws, hs);
pinnedView.layout(0, 0, pinnedView.getMeasuredWidth(), pinnedView.getMeasuredHeight());
mTranslateY = 0;
// initialize pinned shadow
pinnedShadow.view = pinnedView;
pinnedShadow.position = position;
pinnedShadow.id = getAdapter().getItemId(position);
// store pinned shadow
mPinnedSection = pinnedShadow;
}
/** Destroy shadow wrapper for currently pinned view */
void destroyPinnedShadow() {
if (mPinnedSection != null) {
// keep shadow for being recycled later
mRecycleSection = mPinnedSection;
mPinnedSection = null;
}
}
/** Makes sure we have an actual pinned shadow for given position. */
void ensureShadowForPosition(int sectionPosition, int firstVisibleItem, int visibleItemCount) {
if (visibleItemCount < 2) { // no need for creating shadow at all, we have a single visible item
destroyPinnedShadow();
return;
}
if (mPinnedSection != null
&& mPinnedSection.position != sectionPosition) { // invalidate shadow, if required
destroyPinnedShadow();
}
if (mPinnedSection == null) { // create shadow, if empty
createPinnedShadow(sectionPosition);
}
// align shadow according to next section position, if needed
int nextPosition = sectionPosition + 1;
if (nextPosition < getCount()) {
int nextSectionPosition = findFirstVisibleSectionPosition(nextPosition,
visibleItemCount - (nextPosition - firstVisibleItem));
if (nextSectionPosition > -1) {
View nextSectionView = getChildAt(nextSectionPosition - firstVisibleItem);
final int bottom = mPinnedSection.view.getBottom() + getPaddingTop();
mSectionsDistanceY = nextSectionView.getTop() - bottom;
if (mSectionsDistanceY < 0) {
// next section overlaps pinned shadow, move it up
mTranslateY = mSectionsDistanceY;
} else {
// next section does not overlap with pinned, stick to top
mTranslateY = 0;
}
} else {
// no other sections are visible, stick to top
mTranslateY = 0;
mSectionsDistanceY = Integer.MAX_VALUE;
}
}
}
int findFirstVisibleSectionPosition(int firstVisibleItem, int visibleItemCount) {
ListAdapter adapter = getAdapter();
int adapterDataCount = adapter.getCount();
if (getLastVisiblePosition() >= adapterDataCount) return -1; // dataset has changed, no candidate
if (firstVisibleItem+visibleItemCount >= adapterDataCount){//added to prevent index Outofbound (in case)
visibleItemCount = adapterDataCount-firstVisibleItem;
}
for (int childIndex = 0; childIndex < visibleItemCount; childIndex++) {
int position = firstVisibleItem + childIndex;
int viewType = adapter.getItemViewType(position);
if (isItemViewTypePinned(adapter, viewType)) return position;
}
return -1;
}
int findCurrentSectionPosition(int fromPosition) {
ListAdapter adapter = getAdapter();
if (fromPosition >= adapter.getCount()) return -1; // dataset has changed, no candidate
if (adapter instanceof SectionIndexer) {
// try fast way by asking section indexer
SectionIndexer indexer = (SectionIndexer) adapter;
int sectionPosition = indexer.getSectionForPosition(fromPosition);
int itemPosition = indexer.getPositionForSection(sectionPosition);
int typeView = adapter.getItemViewType(itemPosition);
if (isItemViewTypePinned(adapter, typeView)) {
return itemPosition;
} // else, no luck
}
// try slow way by looking through to the next section item above
for (int position=fromPosition; position>=0; position--) {
int viewType = adapter.getItemViewType(position);
if (isItemViewTypePinned(adapter, viewType)) return position;
}
return -1; // no candidate found
}
void recreatePinnedShadow() {
destroyPinnedShadow();
ListAdapter adapter = getAdapter();
if (adapter != null && adapter.getCount() > 0) {
int firstVisiblePosition = getFirstVisiblePosition();
int sectionPosition = findCurrentSectionPosition(firstVisiblePosition);
if (sectionPosition == -1) return; // no views to pin, exit
ensureShadowForPosition(sectionPosition,
firstVisiblePosition, getLastVisiblePosition() - firstVisiblePosition);
}
}
@Override
public void setOnScrollListener(OnScrollListener listener) {
if (listener == mOnScrollListener) {
super.setOnScrollListener(listener);
} else {
mDelegateOnScrollListener = listener;
}
}
@Override
public void onRestoreInstanceState(Parcelable state) {
super.onRestoreInstanceState(state);
post(new Runnable() {
@Override public void run() { // restore pinned view after configuration change
recreatePinnedShadow();
}
});
}
@Override
public void setAdapter(ListAdapter adapter) {
// assert adapter in debug mode
if (BuildConfig.DEBUG && adapter != null) {
if (!(adapter instanceof PinnedSectionListAdapter))
throw new IllegalArgumentException("Does your adapter implement PinnedSectionListAdapter?");
if (adapter.getViewTypeCount() < 2)
throw new IllegalArgumentException("Does your adapter handle at least two types" +
" of views in getViewTypeCount() method: items and sections?");
}
// unregister observer at old adapter and register on new one
ListAdapter oldAdapter = getAdapter();
if (oldAdapter != null) oldAdapter.unregisterDataSetObserver(mDataSetObserver);
if (adapter != null) adapter.registerDataSetObserver(mDataSetObserver);
// destroy pinned shadow, if new adapter is not same as old one
if (oldAdapter != adapter) destroyPinnedShadow();
super.setAdapter(adapter);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (mPinnedSection != null) {
int parentWidth = r - l - getPaddingLeft() - getPaddingRight();
int shadowWidth = mPinnedSection.view.getWidth();
if (parentWidth != shadowWidth) {
recreatePinnedShadow();
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mPinnedSection != null) {
// prepare variables
int pLeft = getListPaddingLeft();
int pTop = getListPaddingTop();
View view = mPinnedSection.view;
// draw child
canvas.save();
int clipHeight = view.getHeight() +
(mShadowDrawable == null ? 0 : Math.min(mShadowHeight, mSectionsDistanceY));
canvas.clipRect(pLeft, pTop, pLeft + view.getWidth(), pTop + clipHeight);
canvas.translate(pLeft, pTop + mTranslateY);
drawChild(canvas, mPinnedSection.view, getDrawingTime());
if (mShadowDrawable != null && mSectionsDistanceY > 0) {
mShadowDrawable.setBounds(mPinnedSection.view.getLeft(),
mPinnedSection.view.getBottom(),
mPinnedSection.view.getRight(),
mPinnedSection.view.getBottom() + mShadowHeight);
mShadowDrawable.draw(canvas);
}
canvas.restore();
}
}
//-- touch handling methods
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
final float x = ev.getX();
final float y = ev.getY();
final int action = ev.getAction();
if (action == MotionEvent.ACTION_DOWN
&& mTouchTarget == null
&& mPinnedSection != null
&& isPinnedViewTouched(mPinnedSection.view, x, y)) { // create touch target
// user touched pinned view
mTouchTarget = mPinnedSection.view;
mTouchPoint.x = x;
mTouchPoint.y = y;
// copy down event for eventually be used later
mDownEvent = MotionEvent.obtain(ev);
}
if (mTouchTarget != null) {
if (isPinnedViewTouched(mTouchTarget, x, y)) { // forward event to pinned view
mTouchTarget.dispatchTouchEvent(ev);
}
if (action == MotionEvent.ACTION_UP) { // perform onClick on pinned view
super.dispatchTouchEvent(ev);
performPinnedItemClick();
clearTouchTarget();
} else if (action == MotionEvent.ACTION_CANCEL) { // cancel
clearTouchTarget();
} else if (action == MotionEvent.ACTION_MOVE) {
if (Math.abs(y - mTouchPoint.y) > mTouchSlop) {
// cancel sequence on touch target
MotionEvent event = MotionEvent.obtain(ev);
event.setAction(MotionEvent.ACTION_CANCEL);
mTouchTarget.dispatchTouchEvent(event);
event.recycle();
// provide correct sequence to super class for further handling
super.dispatchTouchEvent(mDownEvent);
super.dispatchTouchEvent(ev);
clearTouchTarget();
}
}
return true;
}
// call super if this was not our pinned view
return super.dispatchTouchEvent(ev);
}
private boolean isPinnedViewTouched(View view, float x, float y) {
view.getHitRect(mTouchRect);
// by taping top or bottom padding, the list performs on click on a border item.
// we don't add top padding here to keep behavior consistent.
mTouchRect.top += mTranslateY;
mTouchRect.bottom += mTranslateY + getPaddingTop();
mTouchRect.left += getPaddingLeft();
mTouchRect.right -= getPaddingRight();
return mTouchRect.contains((int)x, (int)y);
}
private void clearTouchTarget() {
mTouchTarget = null;
if (mDownEvent != null) {
mDownEvent.recycle();
mDownEvent = null;
}
}
private boolean performPinnedItemClick() {
if (mPinnedSection == null) return false;
OnItemClickListener listener = getOnItemClickListener();
if (listener != null && getAdapter().isEnabled(mPinnedSection.position)) {
View view = mPinnedSection.view;
playSoundEffect(SoundEffectConstants.CLICK);
if (view != null) {
view.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
}
listener.onItemClick(this, view, mPinnedSection.position, mPinnedSection.id);
return true;
}
return false;
}
public static boolean isItemViewTypePinned(ListAdapter adapter, int viewType) {
if (adapter instanceof HeaderViewListAdapter) {
adapter = ((HeaderViewListAdapter)adapter).getWrappedAdapter();
}
return ((PinnedSectionListAdapter) adapter).isItemViewTypePinned(viewType);
}
}
第二次在这里弄错误：
SimpleAdapter adapt = new SimpleAdapter(_context, result, resultT, count, android.R.layout.simple_list_item_1, android.R.id.text1);
setListAdapter(adapt);
1 个答案:
答案 0 :(得分：0)
你没有正确使用PinnedSectionListActivity当前参考，如果你想在任何其他类中访问当前的公共函数，那么你必须传递当前的活动参考：
<强>声明
私有上下文上下文;
获取当前活动参考
public PinnedSectionListView(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
initView();
}
public PinnedSectionListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.context = context;
initView();
}
在onScroll（）中使用当前活动参考：
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
}
if(firstVisibleItem+visibleItemCount == totalItemCount && totalItemCount!=0)
{
if(context!=null){
((PinnedSectionListActivity)context).cleans();
}
}else {
// get expected adapter or fail fast
ListAdapter adapter = getAdapter();
if (adapter == null || visibleItemCount == 0) return; // nothing to do
final boolean isFirstVisibleItemSection = isItemViewTypePinned(adapter, adapter.getItemViewType(firstVisibleItem));
if (isFirstVisibleItemSection) {
View sectionView = getChildAt(0);
if (sectionView.getTop() == getPaddingTop()) { // view sticks to the top, no need for pinned shadow
destroyPinnedShadow();
} else { // section doesn't stick to the top, make sure we have a pinned shadow
ensureShadowForPosition(firstVisibleItem, firstVisibleItem, visibleItemCount);
}
} else { // section is not at the first visible position
int sectionPosition = findCurrentSectionPosition(firstVisibleItem);
if (sectionPosition > -1) { // we have section position
ensureShadowForPosition(sectionPosition, firstVisibleItem, visibleItemCount);
} else { // there is no section for the first visible item, destroy shadow
destroyPinnedShadow();
}
}
}
};
PinnedSectionListView完整活动代码：
public class PinnedSectionListView extends ListView {
//-- inner classes
/** List adapter to be implemented for being used with PinnedSectionListView adapter. */
public static interface PinnedSectionListAdapter extends ListAdapter {
/** This method shall return 'true' if views of given type has to be pinned. */
boolean isItemViewTypePinned(int viewType);
}
/** Wrapper class for pinned section view and its position in the list. */
static class PinnedSection {
public View view;
public int position;
public long id;
}
//-- class fields
// fields used for handling touch events
private final Rect mTouchRect = new Rect();
private final PointF mTouchPoint = new PointF();
private int mTouchSlop;
private View mTouchTarget;
private MotionEvent mDownEvent;
// fields used for drawing shadow under a pinned section
private GradientDrawable mShadowDrawable;
private int mSectionsDistanceY;
private int mShadowHeight;
/** Delegating listener, can be null. */
OnScrollListener mDelegateOnScrollListener;
/** Shadow for being recycled, can be null. */
PinnedSection mRecycleSection;
/** shadow instance with a pinned view, can be null. */
PinnedSection mPinnedSection;
/** Pinned view Y-translation. We use it to stick pinned view to the next section. */
int mTranslateY;
private Context context;
/** Scroll listener which does the magic */
private final OnScrollListener mOnScrollListener = new OnScrollListener() {
@Override public void onScrollStateChanged(AbsListView view, int scrollState) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScrollStateChanged(view, scrollState);
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
}
if(firstVisibleItem+visibleItemCount == totalItemCount && totalItemCount!=0)
{
if(context!=null){
((PinnedSectionListActivity)context).cleans();
}
}else {
// get expected adapter or fail fast
ListAdapter adapter = getAdapter();
if (adapter == null || visibleItemCount == 0) return; // nothing to do
final boolean isFirstVisibleItemSection = isItemViewTypePinned(adapter, adapter.getItemViewType(firstVisibleItem));
if (isFirstVisibleItemSection) {
View sectionView = getChildAt(0);
if (sectionView.getTop() == getPaddingTop()) { // view sticks to the top, no need for pinned shadow
destroyPinnedShadow();
} else { // section doesn't stick to the top, make sure we have a pinned shadow
ensureShadowForPosition(firstVisibleItem, firstVisibleItem, visibleItemCount);
}
} else { // section is not at the first visible position
int sectionPosition = findCurrentSectionPosition(firstVisibleItem);
if (sectionPosition > -1) { // we have section position
ensureShadowForPosition(sectionPosition, firstVisibleItem, visibleItemCount);
} else { // there is no section for the first visible item, destroy shadow
destroyPinnedShadow();
}
}
}
};
};
/** Default change observer. */
private final DataSetObserver mDataSetObserver = new DataSetObserver() {
@Override public void onChanged() {
recreatePinnedShadow();
};
@Override public void onInvalidated() {
recreatePinnedShadow();
}
};
//-- constructors
public PinnedSectionListView(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
initView();
}
public PinnedSectionListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.context = context;
initView();
}
private void initView() {
setOnScrollListener(mOnScrollListener);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
initShadow(true);
}
//-- public API methods
public void setShadowVisible(boolean visible) {
initShadow(visible);
if (mPinnedSection != null) {
View v = mPinnedSection.view;
invalidate(v.getLeft(), v.getTop(), v.getRight(), v.getBottom() + mShadowHeight);
}
}
//-- pinned section drawing methods
public void initShadow(boolean visible) {
if (visible) {
if (mShadowDrawable == null) {
mShadowDrawable = new GradientDrawable(Orientation.TOP_BOTTOM,
new int[] { Color.parseColor("#ffa0a0a0"), Color.parseColor("#50a0a0a0"), Color.parseColor("#00a0a0a0")});
mShadowHeight = (int) (8 * getResources().getDisplayMetrics().density);
}
} else {
if (mShadowDrawable != null) {
mShadowDrawable = null;
mShadowHeight = 0;
}
}
}
/** Create shadow wrapper with a pinned view for a view at given position */
void createPinnedShadow(int position) {
// try to recycle shadow
PinnedSection pinnedShadow = mRecycleSection;
mRecycleSection = null;
// create new shadow, if needed
if (pinnedShadow == null) pinnedShadow = new PinnedSection();
// request new view using recycled view, if such
View pinnedView = getAdapter().getView(position, pinnedShadow.view, PinnedSectionListView.this);
// read layout parameters
LayoutParams layoutParams = (LayoutParams) pinnedView.getLayoutParams();
if (layoutParams == null) {
layoutParams = (LayoutParams) generateDefaultLayoutParams();
pinnedView.setLayoutParams(layoutParams);
}
int heightMode = MeasureSpec.getMode(layoutParams.height);
int heightSize = MeasureSpec.getSize(layoutParams.height);
if (heightMode == MeasureSpec.UNSPECIFIED) heightMode = MeasureSpec.EXACTLY;
int maxHeight = getHeight() - getListPaddingTop() - getListPaddingBottom();
if (heightSize > maxHeight) heightSize = maxHeight;
// measure & layout
int ws = MeasureSpec.makeMeasureSpec(getWidth() - getListPaddingLeft() - getListPaddingRight(), MeasureSpec.EXACTLY);
int hs = MeasureSpec.makeMeasureSpec(heightSize, heightMode);
pinnedView.measure(ws, hs);
pinnedView.layout(0, 0, pinnedView.getMeasuredWidth(), pinnedView.getMeasuredHeight());
mTranslateY = 0;
// initialize pinned shadow
pinnedShadow.view = pinnedView;
pinnedShadow.position = position;
pinnedShadow.id = getAdapter().getItemId(position);
// store pinned shadow
mPinnedSection = pinnedShadow;
}
/** Destroy shadow wrapper for currently pinned view */
void destroyPinnedShadow() {
if (mPinnedSection != null) {
// keep shadow for being recycled later
mRecycleSection = mPinnedSection;
mPinnedSection = null;
}
}
/** Makes sure we have an actual pinned shadow for given position. */
void ensureShadowForPosition(int sectionPosition, int firstVisibleItem, int visibleItemCount) {
if (visibleItemCount < 2) { // no need for creating shadow at all, we have a single visible item
destroyPinnedShadow();
return;
}
if (mPinnedSection != null
&& mPinnedSection.position != sectionPosition) { // invalidate shadow, if required
destroyPinnedShadow();
}
if (mPinnedSection == null) { // create shadow, if empty
createPinnedShadow(sectionPosition);
}
// align shadow according to next section position, if needed
int nextPosition = sectionPosition + 1;
if (nextPosition < getCount()) {
int nextSectionPosition = findFirstVisibleSectionPosition(nextPosition,
visibleItemCount - (nextPosition - firstVisibleItem));
if (nextSectionPosition > -1) {
View nextSectionView = getChildAt(nextSectionPosition - firstVisibleItem);
final int bottom = mPinnedSection.view.getBottom() + getPaddingTop();
mSectionsDistanceY = nextSectionView.getTop() - bottom;
if (mSectionsDistanceY < 0) {
// next section overlaps pinned shadow, move it up
mTranslateY = mSectionsDistanceY;
} else {
// next section does not overlap with pinned, stick to top
mTranslateY = 0;
}
} else {
// no other sections are visible, stick to top
mTranslateY = 0;
mSectionsDistanceY = Integer.MAX_VALUE;
}
}
}
int findFirstVisibleSectionPosition(int firstVisibleItem, int visibleItemCount) {
ListAdapter adapter = getAdapter();
int adapterDataCount = adapter.getCount();
if (getLastVisiblePosition() >= adapterDataCount) return -1; // dataset has changed, no candidate
if (firstVisibleItem+visibleItemCount >= adapterDataCount){//added to prevent index Outofbound (in case)
visibleItemCount = adapterDataCount-firstVisibleItem;
}
for (int childIndex = 0; childIndex < visibleItemCount; childIndex++) {
int position = firstVisibleItem + childIndex;
int viewType = adapter.getItemViewType(position);
if (isItemViewTypePinned(adapter, viewType)) return position;
}
return -1;
}
int findCurrentSectionPosition(int fromPosition) {
ListAdapter adapter = getAdapter();
if (fromPosition >= adapter.getCount()) return -1; // dataset has changed, no candidate
if (adapter instanceof SectionIndexer) {
// try fast way by asking section indexer
SectionIndexer indexer = (SectionIndexer) adapter;
int sectionPosition = indexer.getSectionForPosition(fromPosition);
int itemPosition = indexer.getPositionForSection(sectionPosition);
int typeView = adapter.getItemViewType(itemPosition);
if (isItemViewTypePinned(adapter, typeView)) {
return itemPosition;
} // else, no luck
}
// try slow way by looking through to the next section item above
for (int position=fromPosition; position>=0; position--) {
int viewType = adapter.getItemViewType(position);
if (isItemViewTypePinned(adapter, viewType)) return position;
}
return -1; // no candidate found
}
void recreatePinnedShadow() {
destroyPinnedShadow();
ListAdapter adapter = getAdapter();
if (adapter != null && adapter.getCount() > 0) {
int firstVisiblePosition = getFirstVisiblePosition();
int sectionPosition = findCurrentSectionPosition(firstVisiblePosition);
if (sectionPosition == -1) return; // no views to pin, exit
ensureShadowForPosition(sectionPosition,
firstVisiblePosition, getLastVisiblePosition() - firstVisiblePosition);
}
}
@Override
public void setOnScrollListener(OnScrollListener listener) {
if (listener == mOnScrollListener) {
super.setOnScrollListener(listener);
} else {
mDelegateOnScrollListener = listener;
}
}
@Override
public void onRestoreInstanceState(Parcelable state) {
super.onRestoreInstanceState(state);
post(new Runnable() {
@Override public void run() { // restore pinned view after configuration change
recreatePinnedShadow();
}
});
}
@Override
public void setAdapter(ListAdapter adapter) {
// assert adapter in debug mode
if (BuildConfig.DEBUG && adapter != null) {
if (!(adapter instanceof PinnedSectionListAdapter))
throw new IllegalArgumentException("Does your adapter implement PinnedSectionListAdapter?");
if (adapter.getViewTypeCount() < 2)
throw new IllegalArgumentException("Does your adapter handle at least two types" +
" of views in getViewTypeCount() method: items and sections?");
}
// unregister observer at old adapter and register on new one
ListAdapter oldAdapter = getAdapter();
if (oldAdapter != null) oldAdapter.unregisterDataSetObserver(mDataSetObserver);
if (adapter != null) adapter.registerDataSetObserver(mDataSetObserver);
// destroy pinned shadow, if new adapter is not same as old one
if (oldAdapter != adapter) destroyPinnedShadow();
super.setAdapter(adapter);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (mPinnedSection != null) {
int parentWidth = r - l - getPaddingLeft() - getPaddingRight();
int shadowWidth = mPinnedSection.view.getWidth();
if (parentWidth != shadowWidth) {
recreatePinnedShadow();
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mPinnedSection != null) {
// prepare variables
int pLeft = getListPaddingLeft();
int pTop = getListPaddingTop();
View view = mPinnedSection.view;
// draw child
canvas.save();
int clipHeight = view.getHeight() +
(mShadowDrawable == null ? 0 : Math.min(mShadowHeight, mSectionsDistanceY));
canvas.clipRect(pLeft, pTop, pLeft + view.getWidth(), pTop + clipHeight);
canvas.translate(pLeft, pTop + mTranslateY);
drawChild(canvas, mPinnedSection.view, getDrawingTime());
if (mShadowDrawable != null && mSectionsDistanceY > 0) {
mShadowDrawable.setBounds(mPinnedSection.view.getLeft(),
mPinnedSection.view.getBottom(),
mPinnedSection.view.getRight(),
mPinnedSection.view.getBottom() + mShadowHeight);
mShadowDrawable.draw(canvas);
}
canvas.restore();
}
}
//-- touch handling methods
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
final float x = ev.getX();
final float y = ev.getY();
final int action = ev.getAction();
if (action == MotionEvent.ACTION_DOWN
&& mTouchTarget == null
&& mPinnedSection != null
&& isPinnedViewTouched(mPinnedSection.view, x, y)) { // create touch target
// user touched pinned view
mTouchTarget = mPinnedSection.view;
mTouchPoint.x = x;
mTouchPoint.y = y;
// copy down event for eventually be used later
mDownEvent = MotionEvent.obtain(ev);
}
if (mTouchTarget != null) {
if (isPinnedViewTouched(mTouchTarget, x, y)) { // forward event to pinned view
mTouchTarget.dispatchTouchEvent(ev);
}
if (action == MotionEvent.ACTION_UP) { // perform onClick on pinned view
super.dispatchTouchEvent(ev);
performPinnedItemClick();
clearTouchTarget();
} else if (action == MotionEvent.ACTION_CANCEL) { // cancel
clearTouchTarget();
} else if (action == MotionEvent.ACTION_MOVE) {
if (Math.abs(y - mTouchPoint.y) > mTouchSlop) {
// cancel sequence on touch target
MotionEvent event = MotionEvent.obtain(ev);
event.setAction(MotionEvent.ACTION_CANCEL);
mTouchTarget.dispatchTouchEvent(event);
event.recycle();
// provide correct sequence to super class for further handling
super.dispatchTouchEvent(mDownEvent);
super.dispatchTouchEvent(ev);
clearTouchTarget();
}
}
return true;
}
// call super if this was not our pinned view
return super.dispatchTouchEvent(ev);
}
private boolean isPinnedViewTouched(View view, float x, float y) {
view.getHitRect(mTouchRect);
// by taping top or bottom padding, the list performs on click on a border item.
// we don't add top padding here to keep behavior consistent.
mTouchRect.top += mTranslateY;
mTouchRect.bottom += mTranslateY + getPaddingTop();
mTouchRect.left += getPaddingLeft();
mTouchRect.right -= getPaddingRight();
return mTouchRect.contains((int)x, (int)y);
}
private void clearTouchTarget() {
mTouchTarget = null;
if (mDownEvent != null) {
mDownEvent.recycle();
mDownEvent = null;
}
}
private boolean performPinnedItemClick() {
if (mPinnedSection == null) return false;
OnItemClickListener listener = getOnItemClickListener();
if (listener != null && getAdapter().isEnabled(mPinnedSection.position)) {
View view = mPinnedSection.view;
playSoundEffect(SoundEffectConstants.CLICK);
if (view != null) {
view.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
}
listener.onItemClick(this, view, mPinnedSection.position, mPinnedSection.id);
return true;
}
return false;
}
public static boolean isItemViewTypePinned(ListAdapter adapter, int viewType) {
if (adapter instanceof HeaderViewListAdapter) {
adapter = ((HeaderViewListAdapter)adapter).getWrappedAdapter();
}
return ((PinnedSectionListAdapter) adapter).isItemViewTypePinned(viewType);
}
}
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