可用ListViewAdapter基于BaseAdapter：
public class ContactsListAdapter extends BaseAdapter{
private LayoutInflater inflater;
private ArrayList<ContactsListItems> mContactsList = new ArrayList<>();
ContactsListAdapter(Context context, ArrayList<ContactsListItems> users){
mContactsList = users;
inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
return mContactsList.size();
}
@Override
public Object getItem(int i) {
return mContactsList.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int i, View convertView, ViewGroup viewGroup) {
View view = convertView;
ViewHolder holder;
ContactsListItems user = getUser(i);
if (view == null){
holder = new ViewHolder();
if (user.getUIN() == -9){
view = inflater.inflate(R.layout.contacts_list_header, viewGroup, false);
//((TextView)view.findViewById(R.id.twGroupName_header)).setText(user.getGroupName());
holder.twGroupName_header = (TextView)view.findViewById(R.id.twGroupName_header);
holder.twGroupName_header.setText(user.getGroupName());
view.setTag(R.id.group_id_contacts_listview, -1);
view.setTag(R.id.parent_group_id_contacts_lisview, user.getParentId());
}else {
if (!user.ismIsGroup()) {
view = inflater.inflate(R.layout.item_people_in_contacts, viewGroup, false);
// ((TextView) view.findViewById(R.id.twContactName)).setText(user.getDisplayName());
// ((TextView) view.findViewById(R.id.twUIN)).setText("UIN:" + user.getUIN().toString());
holder.twContactName = (TextView)view.findViewById(R.id.twContactName);
holder.twContactName.setText(user.getDisplayName());
holder.twUIN = (TextView)view.findViewById(R.id.twUIN);
holder.twUIN.setText("UIN:" + user.getUIN().toString());
view.setTag(R.id.group_id_contacts_listview, user.getGroupId());
} else {
view = inflater.inflate(R.layout.item_group_in_contacts, viewGroup, false);
//((TextView) view.findViewById(R.id.twGroupName_contacts)).setText((user.getGroupName()));
holder.twGroupName_contacts = (TextView)view.findViewById(R.id.twGroupName_contacts);
holder.twGroupName_contacts.setText(user.getGroupName());
view.setTag(R.id.group_id_contacts_listview, user.getGroupId());
}
}
view.setTag(holder);
} else {
holder = (ViewHolder)view.getTag();
}
return view;
}
private ContactsListItems getUser(int position) {
return ((ContactsListItems) getItem(position));
}
private static class ViewHolder{
TextView twContactName;
TextView twUIN;
TextView twGroupName_contacts;
TextView twGroupName_header;
}
}
以及 ListView 中填充数据的片段：
public class Contacts extends Fragment {
public ContactsListAdapter adapter;
ArrayList<ContactsListItems> items = new ArrayList<>();
String CONTACTS_LIST = "contacts_list";
@Override
public View onCreateView(final LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.fragment_contacts, container, false);
SharedPreferences spref = MainPage.contextOfApplication.getSharedPreferences(Consts.APP_PREFERENCES, MainPage.MODE_PRIVATE);
final String sData = spref.getString(CONTACTS_LIST, "");
ContactsListItems Item;
try {
JSONArray contactsListJson = new JSONArray(sData);
for (int i=0; i<contactsListJson.length(); i++){
JSONObject user = contactsListJson.getJSONObject(i);
if (user.getBoolean("IsGroup") && user.getInt("ParentID") == 0) {
Item = new ContactsListItems(user.getInt("UIN"),
user.getInt("Sex"),
user.getInt("ParentID"),
user.getInt("ID"),
user.getString("DisplayName"),
user.getString("GroupName"),
user.getBoolean("TeamLead"),
user.getBoolean("IsGroup"),
user.getInt("GroupID"));
items.add(Item);
}
}
}catch (JSONException e){
}
adapter = new ContactsListAdapter(getActivity(), items);
final ListView listView = (ListView)view.findViewById(R.id.lwContacts);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
Integer GroupId = (Integer) view.getTag(R.id.group_id_contacts_listview);
Integer parentGroupId = (Integer) view.getTag(R.id.parent_group_id_contacts_lisview);
ContactsListItems ItemsOnClick;
ArrayList<ContactsListItems> itemsOnClick = new ArrayList<>();
//------------------------------Обработка нажатия на группу-------------------------------------
if (GroupId > 0) {
try {
JSONArray contactsListJson = new JSONArray(sData);
for (int j = 0; j < contactsListJson.length(); j++) {
JSONObject user = contactsListJson.getJSONObject(j);
if (user.getInt("GroupID") == GroupId){
ContactsListItems headerItem = new ContactsListItems(-9,0,user.getInt("ParentID"),0,"", user.getString("GroupName"), false, false, user.getInt("GroupID"));
itemsOnClick.add(headerItem);
}
if (user.getInt("ParentID") == GroupId) {
ItemsOnClick = new ContactsListItems(user.getInt("UIN"),
user.getInt("Sex"),
user.getInt("ParentID"),
user.getInt("ID"),
user.getString("DisplayName"),
user.getString("GroupName"),
user.getBoolean("TeamLead"),
user.getBoolean("IsGroup"),
user.getInt("GroupID"));
itemsOnClick.add(ItemsOnClick);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
ContactsListAdapter onClickAdapter = new ContactsListAdapter(getActivity(), itemsOnClick);
listView.setAdapter(onClickAdapter);
//------------------------------Обработка нажатия на группу-------------------------------------
} else
//------------------------------Обработка нажатия на контакт-------------------------------------
if (GroupId == 0){
Toast t = Toast.makeText(getActivity(), "Contact", Toast.LENGTH_SHORT);
t.show();
//------------------------------Обработка нажатия на контакт-------------------------------------
} else
//------------------------------Обработка нажатия на header--------------------------------------
if (GroupId == -1){
ArrayList<ContactsListItems> itemsOnBackClick = new ArrayList<>();
try {
JSONArray backJson = new JSONArray(sData);
ContactsListItems ItemsOnBackClick;
for (int k=0; k<backJson.length(); k++){
JSONObject backUser = backJson.getJSONObject(k);
if ((backUser.getInt("GroupID") == parentGroupId) && parentGroupId != 0){
ContactsListItems headerItem = new ContactsListItems(-9,0,backUser.getInt("ParentID"),0,"", backUser.getString("GroupName"), false, false, backUser.getInt("GroupID"));
itemsOnBackClick.add(headerItem);
}
if (backUser.getInt("ParentID") == parentGroupId) {
ItemsOnBackClick = new ContactsListItems(backUser.getInt("UIN"),
backUser.getInt("Sex"),
backUser.getInt("ParentID"),
backUser.getInt("ID"),
backUser.getString("DisplayName"),
backUser.getString("GroupName"),
backUser.getBoolean("TeamLead"),
backUser.getBoolean("IsGroup"),
backUser.getInt("GroupID"));
itemsOnBackClick.add(ItemsOnBackClick);
}
ContactsListAdapter onBackClickAdapter = new ContactsListAdapter(getActivity(), itemsOnBackClick);
listView.setAdapter(onBackClickAdapter);
}
}catch (JSONException e){
e.printStackTrace();
}
}
//------------------------------Обработка нажатия на header--------------------------------------
}
});
return view;
}
}
我正在尝试实现一个多级列表。使用少量元素，一切正常，但一旦元素多于手机屏幕上显示的内容，当滚动 ListView 时，元素开始打乱。嵌套在其中的功能会保留，但顺序不会。
有没有人猜到为什么？
像这样更改了 getView() 方法：
public View getView(int i, View convertView, ViewGroup viewGroup) {
View view = convertView;
ViewHolder holder;
ContactsListItems user = getUser(i);
if (view == null){
holder = new ViewHolder();
if (user.getUIN() == -9){
view = inflater.inflate(R.layout.contacts_list_header, viewGroup, false);
holder.twGroupName_header = (TextView)view.findViewById(R.id.twGroupName_header);
view.setTag(R.id.group_id_contacts_listview, -1);
view.setTag(R.id.parent_group_id_contacts_lisview, user.getParentId());
}else {
if (!user.ismIsGroup()) {
view = inflater.inflate(R.layout.item_people_in_contacts, viewGroup, false);
holder.twContactName = (TextView)view.findViewById(R.id.twContactName);
holder.twUIN = (TextView)view.findViewById(R.id.twUIN);
view.setTag(R.id.group_id_contacts_listview, user.getGroupId());
} else {
view = inflater.inflate(R.layout.item_group_in_contacts, viewGroup, false);
holder.twGroupName_contacts = (TextView)view.findViewById(R.id.twGroupName_contacts);
view.setTag(R.id.group_id_contacts_listview, user.getGroupId());
}
}
view.setTag(holder);
} else {
holder = (ViewHolder)view.getTag();
}
if (user.getUIN() == -9){
holder.twGroupName_header.setText(user.getGroupName());
}else {
if (!user.ismIsGroup()) {
holder.twContactName.setText(user.getDisplayName());
holder.twUIN.setText("UIN:" + user.getUIN().toString());
} else {
holder.twGroupName_contacts.setText(user.getGroupName());
}
}
return view;
}
但是现在，滚动时，当我到达列表末尾时，会发生错误：
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
虽然我很可能会放弃 \u200b\u200busing 的想法而
ListView支持RecyclerView，但我仍然找到了解决方案。感谢@post_zeew 提供的提示和信息。ListView适配器代码：
Основными изменениями стало переопределение методов
getItemViewType()иgetViewTypeCount(). В первый я вынес логику сортировки данных, во втором указал количество разных layout-ов. Причем пока не переопределилgetViewTypeCount(), ничего не работало.