我一直在使用适配器，并尝试使用notifydatasetchanged更新它。但我面临的问题是，在我成功更新适配器后，我可以看到列表视图中已经进行了更改，然后在从其他片段返回后，它将更改回以前的数据。我听说适配器将重用转换视图和导致问题的相同数据，但我不知道如何解决这个问题。我已经搜索了答案，但找不到类似的东西，因为大多数答案都是关于声明一个新的适配器。 以下是我的代码的一部分：
1.片段中的刷新方法
public void toggleRefreshInBackground(ArrayList<HashMap<String, Object>> list) {
dialog_list.clear();
dialog_list.addAll(list);
adapter.update(list);
}
我的适配器的2.getView（）
public class DialogListAdapter extends BaseAdapter {
Context context;
private ImageLoader imageLoader;
private static LayoutInflater inflater;
private ArrayList<HashMap<String, Object>> member_list;
private ArrayList<HashMap<String, Object>> member_list2;
private SparseBooleanArray mSelectedItemsIds;
private ArrayList<Integer> selectedItemPosition;
//private static final int droidGreen = Color.parseColor("#A4C639");
//private BadgeView badge;
Resources res;
String sorting;
public DialogListAdapter(Context c,
ArrayList<HashMap<String, Object>>content, String temp_sorting) {
inflater=(LayoutInflater)c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
this.context=c;
this.member_list = content;
this.member_list2 = new ArrayList<>();
this.member_list2.addAll(this.member_list);
res=c.getResources();
this.sorting = temp_sorting;
mSelectedItemsIds = new SparseBooleanArray();
selectedItemPosition = new ArrayList<>();
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return member_list.size();
}
@Override
public HashMap<String, Object> getItem(int position) {
// TODO Auto-generated method stub
return member_list.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
public void update(ArrayList<HashMap<String,Object>> obj) {
member_list2.clear();
member_list2.addAll(obj);
notifyDataSetChanged();
}
public final class DialogListItem{ // view holder
public TextView read_count;
public TextView nameView;
public TextView numberView;
public TextView statusView;
public ImageView thumb_image;
public TextView timeView;
public TextView senderView;
public ImageView tick;
//public BadgeView badge;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
int index;
if(sorting.equals("D")){
index = member_list.size()-position-1;
}else{
index = position;
}
View row = convertView;
DialogListItem dialogItem=null;
String textbuff_time = null;
String textbuff_mess = null;
String textbuff_sender = null;
if (convertView==null){
row=inflater.inflate(R.layout.dialog_list_single, null);
dialogItem=new DialogListItem();
dialogItem.read_count=(TextView)row.findViewById(R.id.readcount);
dialogItem.nameView=(TextView)row.findViewById(R.id.member_name);
dialogItem.numberView=(TextView)row.findViewById(R.id.tab2number);
dialogItem.statusView=(TextView)row.findViewById(R.id.tab2status);
dialogItem.thumb_image=(ImageView)row.findViewById(R.id.tab2image);
dialogItem.timeView=(TextView) row.findViewById(R.id.tab2date);
dialogItem.senderView=(TextView) row.findViewById(R.id.tab2sender);
dialogItem.tick = (ImageView) row.findViewById(R.id.tick);
row.setTag(dialogItem);
}
else{
dialogItem=(DialogListItem) row.getTag();
}
if (mSelectedItemsIds.get(position)) {
row.setBackgroundColor(context.getResources().getColor(R.color.item_selected));
} else {
row.setBackgroundColor(context.getResources().getColor(R.color.item_unselected));
}
HashMap<String,Object>items;
items=member_list.get(index);
dialogItem.nameView.setText((String)items.get(DBhelper.MEMBER_NAME));
dialogItem.nameView.setTypeface(null,Typeface.BOLD);
dialogItem.nameView.setSingleLine(true);
dialogItem.nameView.setMaxLines(1);
dialogItem.nameView.setEms(13);
dialogItem.nameView.setEllipsize(TruncateAt.END);
dialogItem.numberView.setText((String)items.get(DBhelper.MEMBER_NUMBER));
String textbuff=(String)items.get(DBhelper.MEMBER_LMESSAGE);
if (!TextUtils.isEmpty(textbuff)){
textbuff_time=textbuff.substring(0, 19);
textbuff_mess=textbuff.substring(20);
int bound=textbuff_mess.indexOf("½");
if(bound!=-1){
textbuff_sender=textbuff_mess.substring(0,bound);
textbuff_mess=textbuff_mess.substring(bound+2);
}
else
textbuff_sender="";
dialogItem.statusView.setText(textbuff_mess);
if (textbuff_sender.equals(context.getResources().getString(R.string.myself))) {
dialogItem.senderView.setVisibility(View.GONE);
dialogItem.tick.setVisibility(View.VISIBLE);
} else {
textbuff_sender = textbuff_sender + ": ";
dialogItem.senderView.setVisibility(View.VISIBLE);
dialogItem.senderView.setText(textbuff_sender);
dialogItem.tick.setVisibility(View.GONE);
}
try {
dialogItem.timeView.setText(Utility.relativeTime(row.getContext(), textbuff_time));
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else{
dialogItem.statusView.setText("");
dialogItem.senderView.setText("");
dialogItem.timeView.setText("---");
}
dialogItem.statusView.setTextColor(Color.GRAY);
dialogItem.statusView.setTypeface(null,Typeface.NORMAL);
dialogItem.timeView.setTextColor(Color.GRAY);
dialogItem.timeView.setTypeface(null,Typeface.NORMAL);
dialogItem.senderView.setTextColor(Color.GRAY);
dialogItem.senderView.setTypeface(null,Typeface.NORMAL);
dialogItem.senderView.getPaint().setTextSkewX(-0.25f);
String sformat=" "+String.valueOf(items.get(DBhelper.MEMBER_SIZE))+" ";
dialogItem.read_count.setText(sformat);
int badge_number=(Integer)items.get(DBhelper.MEMBER_SIZE);
if(badge_number>0){
dialogItem.read_count.setVisibility(View.VISIBLE);
dialogItem.statusView.setTextColor(Color.BLACK);
dialogItem.statusView.setTypeface(null,Typeface.BOLD);
dialogItem.timeView.setTextColor(Color.BLACK);
dialogItem.timeView.setTypeface(null,Typeface.BOLD);
dialogItem.senderView.setTextColor(Color.BLACK);
dialogItem.senderView.setTypeface(null,Typeface.BOLD);
dialogItem.senderView.getPaint().setTextSkewX(-0.25f);
}
else{
dialogItem.read_count.setVisibility(View.GONE);
}
StringBuffer link=new StringBuffer(Register.get_current_server_address());
if(items.get(DBhelper.MEMBER_TYPE).equals(res.getString(R.string.broadcast_chat))){
dialogItem.nameView.setTextColor(row.getResources().getColor(R.color.tab4_title));
link.append("uniappSystemFile.asp");
link.append("?file=").append("broadcast.png");
//imageLoader.DisplayImage(link.toString(), dialogItem.thumb_image);
Picasso.with(context).load(link.toString()).transform(new CircleTransform()).resize(200,200).into(dialogItem.thumb_image);
dialogItem.read_count.setVisibility(View.GONE); // disable broadcast badge
}
Picasso.with(context).load(R.drawable.ic_contact).resize(200,200).into(dialogItem.thumb_image);
Picasso.with(context).load(R.drawable.ic_notif).resize(200, 200).into(dialogItem.thumb_image);
}else{
link2 = new IMService(context.getApplicationContext()).group_image_thumb_get(tab2.myphone, (String) items.get(DBhelper.MEMBER_NUMBER));
dialogItem.nameView.setTextColor(row.getResources().getColor(R.color.tab3_title));
//imageLoader.DisplayImage(link2, dialogItem.thumb_image);
Picasso.with(context).load(link2).transform(new CircleTransform()).resize(200, 200).placeholder(R.drawable.ic_group_circle_black_48dp).error(R.drawable.ic_group_circle_black_48dp).into(dialogItem.thumb_image);
}
}
public void setSearchPattern(String pattern) {
filterListByPattern(pattern.trim());
this.notifyDataSetChanged();
}
private void filterListByPattern(String searchPattern) {
member_list.clear();
for (HashMap<String,Object> info : member_list2) {
boolean add = true;
do {
if (searchPattern == null || searchPattern.equals("")) {
break;
}
if (info.get(DBhelper.MEMBER_NAME).toString().toLowerCase().contains(searchPattern)) {
break;
}
add = false;
} while (false);
if (add) {
member_list.add(info);
}
}
}
public void resetList() {
this.member_list2 = new ArrayList<HashMap<String,Object>>();
this.member_list2.addAll(this.member_list);
this.notifyDataSetChanged();
}
public void remove(Object object) {
member_list.remove(object);
notifyDataSetChanged();
}
public void toggleSelection(int position) {
selectView(position, !mSelectedItemsIds.get(position));
}
public void removeSelection() {
mSelectedItemsIds = new SparseBooleanArray();
selectedItemPosition = new ArrayList<>();
notifyDataSetChanged();
}
public void selectView(int position, boolean value) {
if (value) {
mSelectedItemsIds.put(position, value);
selectedItemPosition.add(position);
} else {
mSelectedItemsIds.delete(position);
selectedItemPosition.remove(selectedItemPosition.indexOf(position));
}
notifyDataSetChanged();
}
public int getSelectedCount() {
return mSelectedItemsIds.size();
}
public SparseBooleanArray getSelectedIds() {
return mSelectedItemsIds;
}
public ArrayList<Integer> getItemPosition() {
return selectedItemPosition;
}
}
所以，我的问题是为什么我的适配器和listview在从其他片段返回到此片段后显示旧数据，以及如何解决这个问题？
P.S。请不要告诉我申报这样的新适配器
adapter = new MyAdapter(list);
adapter.notifyDataSetChanged();
我知道它有效，但它不是一个好的和适当的方法，因为它是一个繁重的操作，你甚至不需要在声明一个新的适配器后使用notifyDataSetChanged。
非常感谢
答案 0 :(得分：0)
尝试放setRetainInstance(true);
在你的片段里面。
如果以上操作不起作用，请尝试使用onSaveInstanceState()，如下所示 -
在顶部声明Parcelable state;
在片段的onpause（）内部保存列表视图状态，state = listview.onSaveInstanceState();或在更改片段时手动保存。
然后在onCreateView中检查state是否为空。如果为null，则设置适配器/获取数据，如果没有则设置
listview.onRestoreInstanceState(state);
另一方面，每次加载片段时，ArrayList都将从空开始。所以你需要小心保存数据。