下面列出了android.widget.ListAdapter#getCount ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
/**
* This method is by no means accurate, and Will only work to any degree of accuracy if your list items
* are the same height.
* Otherwise it becomes vastly more difficult to calculate the correct height.
*
* @param listView listView to get height of, if no adapter is attached then nothing will happen.
* @return 0 for failure.
*/
public static int calculateApproximateHeight(AbsListView listView) {
final ListAdapter adapter = listView.getAdapter();
int onScreenHeight = 0, totalHeight = 0;
final int totalCount = adapter.getCount();
final int visibleCount = listView.getLastVisiblePosition() - listView.getFirstVisiblePosition();
if (totalCount > 0) {
View view;
for (int i = 0; i < visibleCount; i++) {
// final View view = adapter.getView(0, null, listView);
view = listView.getChildAt(i);
// view.measure(
// View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
// View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
onScreenHeight += view.getMeasuredHeight();
}
// Get the average on screen height, then multiply it up.
totalHeight = (onScreenHeight / visibleCount) * totalCount;
// Add the divider height.
if (listView instanceof ListView) {
totalHeight += ((ListView) listView).getDividerHeight() * (totalCount - 1);
}
}
return totalHeight;
}
public static void setListViewHeightBasedOnChildren(ListView listView) {
ListAdapter listAdapter = listView.getAdapter();
if (listAdapter == null) {
// pre-condition
return;
}
int totalHeight = 0;
for (int i = 0; i < listAdapter.getCount(); i++) {
View listItem = listAdapter.getView(i, null, listView);
listItem.measure(0, 0);
totalHeight += listItem.getMeasuredHeight();
}
ViewGroup.LayoutParams params = listView.getLayoutParams();
params.height = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount() - 1));
listView.setLayoutParams(params);
if(listView.isInLayout() == false){
listView.requestLayout();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = getMeasuredWidth();
int height = 0;
ListAdapter adapter = getAdapter();
int count = adapter.getCount();
for (int i = 0; i < count; i++) {
View childView = adapter.getView(i, null, this);
childView.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),
MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
height += childView.getMeasuredHeight();
}
Rect bgPadding = new Rect();
getBackground().getPadding(bgPadding);
height += (count - 1) * getDividerHeight() + bgPadding.top + bgPadding.bottom;
setMeasuredDimension(width, height);
}
/**
* ListView转换成bitmap
*
* @param listView
* @return List<Bitmap>
*/
public static List<BitmapWithHeight> getWholeListViewItemsToBitmap(final ListView listView) {
List<BitmapWithHeight> list = new ArrayList<>();
if (listView == null || listView.getAdapter() == null) {
return list;
}
ListAdapter adapter = listView.getAdapter();
int count = adapter.getCount();
for (int i = 0; i < count; i++) {
View childView = adapter.getView(i, null, listView);
list.add(getSimpleViewToBitmap(childView, listView.getMeasuredWidth()));
}
return list;
}
public void setListViewHeightBasedOnChildren(ListView listView) {
// 获取ListView对应的Adapter
ListAdapter listAdapter = listView.getAdapter();
if (listAdapter == null) {
return;
}
int totalHeight = 0;
for (int i = 0, len = listAdapter.getCount(); i < len; i++) {
// listAdapter.getCount()返回数据项的数目
View listItem = listAdapter.getView(i, null, listView);
// 计算子项View 的宽高
listItem.measure(0, 0);
// 统计所有子项的总高度
totalHeight += listItem.getMeasuredHeight();
}
ViewGroup.LayoutParams params = listView.getLayoutParams();
params.height = totalHeight+ (listView.getDividerHeight() * (listAdapter.getCount() - 1));
// listView.getDividerHeight()获取子项间分隔符占用的高度
// params.height最后得到整个ListView完整显示需要的高度
listView.setLayoutParams(params);
}
@Override
public int getSectionForPosition(int position) {
int section=0;
for (ListAdapter piece : getPieces()) {
int size=piece.getCount();
if (position < size) {
if (piece instanceof SectionIndexer) {
return(section + ((SectionIndexer)piece).getSectionForPosition(position));
}
return(0);
}
else {
if (piece instanceof SectionIndexer) {
Object[] sections=((SectionIndexer)piece).getSections();
if (sections != null) {
section+=sections.length;
}
}
}
position-=size;
}
return(0);
}
public long getItemId(int position) {
int size;
for (Iterator i$ = this.getPieces().iterator(); i$.hasNext(); position -= size) {
ListAdapter piece = (ListAdapter) i$.next();
size = piece.getCount();
if (position < size) {
return piece.getItemId(position);
}
}
return -1L;
}
final int[] measureWithLargeChildren(int heightMeasureSpec, int startPosition, int endPosition, int maxWidth, int maxHeight, int disallowPartialChildPosition) {
ListAdapter adapter = this.mAdapter;
if (adapter == null) {
return new int[]{this.mListPadding.left + this.mListPadding.right, this.mListPadding.top + this.mListPadding.bottom};
}
int returnedWidth = this.mListPadding.left + this.mListPadding.right;
int returnedHeight = this.mListPadding.top + this.mListPadding.bottom;
int dividerWidth = (this.mDividerWidth <= 0 || this.mDivider == null) ? 0 : this.mDividerWidth;
int childWidth = 0;
int childHeight = 0;
if (endPosition == -1) {
endPosition = adapter.getCount() - 1;
}
RecycleBin recycleBin = this.mRecycler;
boolean recyle = recycleOnMeasure();
boolean[] isScrap = this.mIsScrap;
for (int i = startPosition; i <= endPosition; i++) {
View child = obtainView(i, isScrap);
measureScrapChildWidth(child, i, heightMeasureSpec);
if (recyle && recycleBin.shouldRecycleViewType(((LayoutParams) child.getLayoutParams()).viewType)) {
recycleBin.addScrapView(child, -1);
}
childWidth = Math.max(childWidth, child.getMeasuredWidth() + dividerWidth);
childHeight = Math.max(childHeight, child.getMeasuredHeight());
}
returnedHeight += childHeight;
return new int[]{Math.min(returnedWidth + childWidth, maxWidth), Math.min(returnedHeight, maxHeight)};
}
/**
* How many items are in the data set represented by this Adapter.
*/
@Override
public int getCount() {
int total = 0;
for (ListAdapter piece : pieces) {
total += piece.getCount();
}
return (total);
}
public static void setListViewHeightBasedOnChildren(GridView listView) {
// 获取listview的adapter
ListAdapter listAdapter = listView.getAdapter();
if (listAdapter == null) {
return;
}
// 固定列宽，有多少列
int col = 3;// listView.getNumColumns();
int totalHeight = 0;
// i每次加4，相当于listAdapter.getCount()小于等于4时 循环一次，计算一次item的高度，
// listAdapter.getCount()小于等于8时计算两次高度相加
for (int i = 0; i < listAdapter.getCount(); i += col) {
// 获取listview的每一个item
View listItem = listAdapter.getView(i, null, listView);
listItem.measure(0, 0);
// 获取item的高度和
totalHeight += listItem.getMeasuredHeight();
}
// 获取listview的布局参数
ViewGroup.LayoutParams params = listView.getLayoutParams();
// 设置高度
params.height = totalHeight;
// 设置margin
((MarginLayoutParams) params).setMargins(10, 10, 10, 10);
// 设置参数
listView.setLayoutParams(params);
}
public ListAdapter getAdapter(int position) {
int size;
for (Iterator i$ = this.getPieces().iterator(); i$.hasNext(); position -= size) {
ListAdapter piece = (ListAdapter) i$.next();
size = piece.getCount();
if (position < size) {
return piece;
}
}
return null;
}
/**
* Get the data item associated with the specified position in the data set.
*
* @param position Position of the item whose data we want
*/
@Override
public Object getItem(int position) {
for (ListAdapter piece : pieces) {
int size = piece.getCount();
if (position < size) {
return (piece.getItem(position));
}
position -= size;
}
return (null);
}
/**
* Get the data item associated with the specified position in the data set.
*
* @param position Position of the item whose data we want
*/
public Object getItem(int position) {
for (ListAdapter piece : pieces) {
int size = piece.getCount();
if (position < size) {
return piece.getItem(position);
}
position -= size;
}
return null;
}
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 setListAdapter(ListAdapter adapter) {
int count = adapter.getCount();
List<Header> headers = new ArrayList<>(count);
for (int i = 0; i < count; ++i) {
headers.add((Header) adapter.getItem(i));
}
super.setListAdapter(new HeaderAdapter(this, headers, R.layout.item_preference_header, true));
}
public void run() {
// The data has changed since we posted this action in the event queue,
// bail out before bad things happen
if (mDataChanged) return;
final ListAdapter adapter = mAdapter;
final int motionPosition = mClickMotionPosition;
if (adapter != null && mItemCount > 0 &&
motionPosition != INVALID_POSITION &&
motionPosition < adapter.getCount() && sameWindow()) {
performItemClick(mChild, motionPosition, adapter.getItemId(motionPosition));
}
}
@Override
protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
final ListAdapter adapter = mAdapter;
if (adapter != null && gainFocus && previouslyFocusedRect != null) {
previouslyFocusedRect.offset(getScrollX(), getScrollY());
// Don't cache the result of getChildCount or mFirstPosition here,
// it could change in layoutChildren.
if (adapter.getCount() < getChildCount() + mFirstPosition) {
mLayoutMode = LAYOUT_NORMAL;
layoutChildren();
}
// figure out which item should be selected based on previously
// focused rect
Rect otherRect = mTempRect;
int minDistance = Integer.MAX_VALUE;
final int childCount = getChildCount();
final int firstPosition = mFirstPosition;
for (int i = 0; i < childCount; i++) {
// only consider selectable views
if (!adapter.isEnabled(firstPosition + i)) {
continue;
}
View other = getChildAt(i);
other.getDrawingRect(otherRect);
offsetDescendantRectToMyCoords(other, otherRect);
int distance = getDistance(previouslyFocusedRect, otherRect, direction);
if (distance < minDistance) {
minDistance = distance;
}
}
}
requestLayout();
}
/**
* Filter key down events. By forwarding key down events to this function,
* views using non-modal ListPopupWindow can have it handle key selection of items.
*
* @param keyCode keyCode param passed to the host view's onKeyDown
* @param event event param passed to the host view's onKeyDown
* @return true if the event was handled, false if it was ignored.
*
* @see #setModal(boolean)
*/
public boolean onKeyDown(int keyCode, KeyEvent event) {
// when the drop down is shown, we drive it directly
if (isShowing()) {
// the key events are forwarded to the list in the drop down view
// note that ListView handles space but we don't want that to happen
// also if selection is not currently in the drop down, then don't
// let center or enter presses go there since that would cause it
// to select one of its items
if (keyCode != KeyEvent.KEYCODE_SPACE
&& (mDropDownList.getSelectedItemPosition() >= 0
|| !isConfirmKey(keyCode))) {
int curIndex = mDropDownList.getSelectedItemPosition();
boolean consumed;
final boolean below = !mPopup.isAboveAnchor();
final ListAdapter adapter = mAdapter;
boolean allEnabled;
int firstItem = Integer.MAX_VALUE;
int lastItem = Integer.MIN_VALUE;
if (adapter != null) {
allEnabled = adapter.areAllItemsEnabled();
firstItem = allEnabled ? 0 :
mDropDownList.lookForSelectablePosition(0, true);
lastItem = allEnabled ? adapter.getCount() - 1 :
mDropDownList.lookForSelectablePosition(adapter.getCount() - 1, false);
}
if ((below && keyCode == KeyEvent.KEYCODE_DPAD_UP && curIndex <= firstItem) ||
(!below && keyCode == KeyEvent.KEYCODE_DPAD_DOWN && curIndex >= lastItem)) {
// When the selection is at the top, we block the key
// event to prevent focus from moving.
clearListSelection();
mPopup.setInputMethodMode(PopupWindow.INPUT_METHOD_NEEDED);
show();
return true;
} else {
// WARNING: Please read the comment where mListSelectionHidden
// is declared
mDropDownList.mListSelectionHidden = false;
}
consumed = mDropDownList.onKeyDown(keyCode, event);
if (DEBUG) Log.v(TAG, "Key down: code=" + keyCode + " list consumed=" + consumed);
if (consumed) {
// If it handled the key event, then the user is
// navigating in the list, so we should put it in front.
mPopup.setInputMethodMode(PopupWindow.INPUT_METHOD_NOT_NEEDED);
// Here's a little trick we need to do to make sure that
// the list view is actually showing its focus indicator,
// by ensuring it has focus and getting its window out
// of touch mode.
mDropDownList.requestFocusFromTouch();
show();
switch (keyCode) {
// avoid passing the focus from the text view to the
// next component
case KeyEvent.KEYCODE_ENTER:
case KeyEvent.KEYCODE_DPAD_CENTER:
case KeyEvent.KEYCODE_DPAD_DOWN:
case KeyEvent.KEYCODE_DPAD_UP:
return true;
}
} else {
if (below && keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
// when the selection is at the bottom, we block the
// event to avoid going to the next focusable widget
if (curIndex == lastItem) {
return true;
}
} else if (!below && keyCode == KeyEvent.KEYCODE_DPAD_UP &&
curIndex == firstItem) {
return true;
}
}
}
}
return false;
}
public void setHeightofListViewBasedOnContent(ListView listView) {
ListAdapter mAdapter = listView.getAdapter();
int totalHeight = 0;
for (int i = 0; i < mAdapter.getCount(); i++) {
totalHeight += getResources().getDimension(R.dimen.item_list_height);
Log.w("HEIGHT" + i, String.valueOf(totalHeight));
}
totalHeight = totalHeight + (listView.getDividerHeight() * (mAdapter.getCount() - 1)) + listView.getPaddingTop();
ViewGroup.LayoutParams params = listView.getLayoutParams();
params.height = totalHeight;
listView.setLayoutParams(params);
listView.requestLayout();
}
private int getItemsCount(ActivityTestRule<SnippetListActivity> snippetListActivityRule){
SnippetListActivity snippetListActivity = snippetListActivityRule.launchActivity(null);
ListAdapter listAdapter = getListAdapter(snippetListActivity);
int numItems = listAdapter.getCount();
snippetListActivity.finish();
return numItems;
}