我有一个列表视图和一个自定义适配器，它可以容纳10个项目并一次显示6个项目，直到用户向下滚动显示最后几个项目。由于我的代码正在选择项目，我将一个接一个地更改每个特定项目的背景颜色，并且它工作正常，直到我点击最后一项并使用：
mailList.smoothScrollToPosition(0);
向上滚动到列表顶部。当发生这种情况时，项目0的背景颜色不会改变，然后一旦我选择了下一个项目，背景颜色会发生变化并继续完美地工作。
要更改我使用此方法的每个项目的背景颜色：
public void selectRow(int position){
// Get the row
View row = getViewByPosition(position, mailList);
// Highlight background colour
row.setBackgroundColor(ContextCompat.getColor(activity, R.color.Pallette_Peach_CC));
// For every other row apart from 'position'
// Check if read/unread and set background colour
View v;
for(int i = 0; i < mailList.getCount(); i++){
if(i != position){
v = getViewByPosition(i, mailList);
if(Consts.mailBox.get(i).isRead()){
v.setBackgroundColor(ContextCompat.getColor(activity, R.color.Ivory_Transparent_55));
}else{
v.setBackgroundColor(ContextCompat.getColor(activity, R.color.Ivory_Transparent_77));
}
}
}
}
使用方法getViewByPosition（）返回视图，以便我可以设置它的颜色：
// returns a specific row
private View getViewByPosition(int pos, ListView listView) {
final int firstListItemPosition = listView.getFirstVisiblePosition();
final int lastListItemPosition = firstListItemPosition + listView.getChildCount() - 1;
if (pos < firstListItemPosition || pos > lastListItemPosition ) {
return listView.getAdapter().getView(pos, null, listView);
} else {
final int childIndex = pos - firstListItemPosition;
return listView.getChildAt(childIndex);
}
}
在第一次迭代时，项目0会改变颜色，但是一旦我到达列表的末尾（其中列表位置9（列表的末尾）最多可见3）并且smoothScroll到第一个（0）位置，项目0的颜色不会改变。要调用selectRow方法，我使用：
if(position == 0) {
mailList.smoothScrollToPosition(0);
selectRow(0);
}
因此它应该向上滚动到列表的顶部，调用selectRow（0）并像第一次迭代那样工作，但它似乎并没有这样做。谁能帮我吗？感谢。
编辑：
这是我的适配器类的getView方法：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
if(view == null){
view = inflater.inflate(R.layout.fragment_mail_row, null);
}
LinearLayout rowContainer = (LinearLayout) view.findViewById(R.id.mailRowContainer);
ImageView mailIcon = (ImageView) view.findViewById(R.id.mailRowImage);
TextView mailTitle = (TextView) view.findViewById(R.id.mailRowTitleText);
TextView mailDate = (TextView) view.findViewById(R.id.mailRowTimeText);
MailItem mMailItem = mail.get(position);
String title = mMailItem.getTitle();
String timestamp;
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
Date today = new Date();
Date messageDate = mMailItem.getDate();
if(sdf.format(today).equals(sdf.format(messageDate))){
// If date of message is today then display the time
SimpleDateFormat tf = new SimpleDateFormat("kk:mm");
timestamp = tf.format(messageDate);
}else{
SimpleDateFormat df = new SimpleDateFormat("dd/MM/yy");
timestamp = df.format(messageDate);
}
// If mail is already opened, re-set the background colour
if(mMailItem.isRead()){
rowContainer.setBackgroundColor(ContextCompat.getColor(activity, R.color.Ivory_Transparent_55));
}else{
rowContainer.setBackgroundColor(ContextCompat.getColor(activity, R.color.Ivory_Transparent_77));
}
// Set the title and time
mailTitle.setText(title);
mailDate.setText(timestamp);
if(mMailItem.getType().equals(Consts.MAIL_TYPE_AUDIO)){
if(mMailItem.isRead()){
mailIcon.setImageResource(R.mipmap.ic_mail_audio_open);
}else{
mailIcon.setImageResource(R.mipmap.ic_mail_audio_closed);
}
}else{
if(mMailItem.isRead()){
mailIcon.setImageResource(R.mipmap.ic_mail_opened);
}else{
mailIcon.setImageResource(R.mipmap.ic_mail_closed);
}
}
return view;
}
编辑2：
为了进一步说明，selectRow方法是从一个名为MailSelector的单独类中调用的，该类完整地在这里：
public class MailSelector {
double noOfItems;
double noOfItemsPerPage;
int noOfPages;
int noOfItemsOnLastPage;
private ListView mailList;
private Activity activity;
public MailSelector(Activity a, ListView list){
this.activity = a;
this.mailList = list;
noOfItemsPerPage = mailList.getLastVisiblePosition() - mailList.getFirstVisiblePosition();
}
public int nextRow(int position){
// Calculate item/page info
noOfItems = mailList.getCount();
if(noOfItems <= noOfItemsPerPage ){
// Only one page so iterate and return to start position
// If only one item or if after last item, select position 0
if(mailList.getChildCount() == 1 || position >= mailList.getCount()){
selectRow(0);
return 0;
}
}else{
// More than one page so handle scrolling
noOfPages = (int) Math.ceil(noOfItems / noOfItemsPerPage);
// Calculate current page. Round down and + 1, as page 1 is actually 0
int currentPage = getCurrentPage(position);
int curPageStartPos = (int) ((int) (noOfItemsPerPage * currentPage) - noOfItemsPerPage);
int curPageEndPos = curPageStartPos + ((int) noOfItemsPerPage - 1);
noOfItemsOnLastPage = (int)(noOfItems % noOfItemsPerPage);
// Scrolling if on last item of page
if(position == curPageEndPos){
// Check if last page
if(currentPage == noOfPages){
// Scroll back to position 0
mailList.smoothScrollToPosition(0);
selectRow(0);
return 0;
}else if(currentPage == noOfPages - 1){
// If page before last
// Get last position of last page
int lastPosOfNextPage = mailList.getCount() - 1;
mailList.smoothScrollToPosition(lastPosOfNextPage);
position = (int) ((position + 1) % noOfItems);
selectRow(position);
}else{
int lastPosOfNextPage = (int) (position + noOfItemsPerPage);
mailList.smoothScrollToPosition(lastPosOfNextPage);
position = (int) ((position + 1) % noOfItems);
selectRow(position);
}
}else{
position = (int) ((position + 1) % noOfItems);
selectRow(position);
}
}
if(position == 0) {
mailList.smoothScrollToPosition(0);
selectRow(0);
}
return position;
}
public void selectRow(int position){
// Get the row
View row = getViewByPosition(position, mailList);
// Highlight background colour
row.setBackgroundColor(ContextCompat.getColor(activity, R.color.Pallette_Peach_CC));
// For every other row apart from 'position'
// Check if read/unread and set background colour
View v;
for(int i = 0; i < mailList.getCount(); i++){
if(i != position){
v = getViewByPosition(i, mailList);
if(Consts.mailBox.get(i).isRead()){
v.setBackgroundColor(ContextCompat.getColor(activity, R.color.Ivory_Transparent_55));
}else{
v.setBackgroundColor(ContextCompat.getColor(activity, R.color.Ivory_Transparent_77));
}
}
}
}
// returns a specific row
private View getViewByPosition(int pos, ListView listView) {
final int firstListItemPosition = listView.getFirstVisiblePosition();
final int lastListItemPosition = firstListItemPosition + listView.getChildCount() - 1;
if (pos < firstListItemPosition || pos > lastListItemPosition ) {
return listView.getAdapter().getView(pos, null, listView);
} else {
final int childIndex = pos - firstListItemPosition;
return listView.getChildAt(childIndex);
}
}
private int getCurrentPage(int position){
return ((int) Math.floor(position / (double) noOfItemsPerPage)) + 1;
}
}