所以基本上我是从 ListView 中的 json url 收集数据。这是一种聊天室类型的应用程序，在列表中我想将聊天室联系人列表与最新消息和时间戳同步。
当 json 更新时，我将调用该函数。
public void addGroupAdapter() {
Firebase jsonurl = new Firebase("firebase url");
jsonurl.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
ContactListAdapter adapter = new ContactListAdapter(getContext(),dataSnapshot);
try {
Log.i("Response Array fire",new JSONArray(dataSnapshot.getValue(String.class)).toString());
if (!adapted){
chatLists.setAdapter(adapter);
adapted = true;
}else {
Log.i("update",dataSnapshot.getValue(String.class));
adapter.setContactList(dataSnapshot);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
该 Json 数据存储在 firebase 数据库中。
chatLists.setAdapter(adapter) 效果很好。
但是当我尝试更新时。 notifyDataSetChanged(); 不起作用。
new ContactListAdapter(getContext(),dataSnapshot).notifyDataSetChanged();
我也尝试过invalidateviews方法并得到相同的结果。那么我哪里做错了？
阅读答案后我尝试了这个。现在这是我的适配器类，
class ContactListAdapter extends BaseAdapter {
Context c;
List lists;
Type type = new TypeToken<List<ChatroomLists>>(){}.getType();
JsonParser parser = new JsonParser();
ArrayList<ChatroomLists> ob1 = new ArrayList<ChatroomLists>();
public void setContactList(DataSnapshot dataSnapshot) {
Type listType = new TypeToken<ArrayList<ChatroomLists>>() {
}.getType();
ob1 = new Gson().fromJson((JsonArray)parser.parse(dataSnapshot.getValue(String.class)),listType);
Log.i("setContactList",dataSnapshot.getValue(String.class));
notifyDataSetChanged();
}
ContactListAdapter(Context c, DataSnapshot group_name) {
this.c = c;
this.groupids = group_name;
Type listType = new TypeToken<ArrayList<ChatroomLists>>() {
}.getType();
ob1 = new Gson().fromJson((JsonArray)parser.parse(group_name.getValue(String.class)),listType);
}
@Override
public int getCount() {
return ob1.size();
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
View row = convertView;
GroupChat.viewHolder holder = null;
if (row == null) {
LayoutInflater inflater = (LayoutInflater) c.getSystemService (Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate (R.layout.chat_list_style, parent, false);
holder = new GroupChat.viewHolder(row);
row.setTag (holder);
} else {
holder = (GroupChat.viewHolder) row.getTag ();
}
ChatroomLists chatroomLists = ob1.get(position);
Iterator<ChatroomLists> iter = ob1.iterator();
String id = chatroomLists.getId();
String time = chatroomLists.getTimestamp();
Log.i("updated data",id + time);
viewHolder finalHolder = holder;
Firebase chatlink = new Firebase ("firebase link");
chatlink.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot d: dataSnapshot.getChildren()){
finalHolder.user_message.setText (dataSnapshot.child(d.getKey()).child("message").getValue(String.class));
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
Firebase imageurl = new Firebase("firebase link");
imageurl.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
Glide.with (getActivity ())
.load (dataSnapshot.getValue(String.class))
.error (R.drawable.man)
.into (finalHolder.user_img);
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
holder.user_name.setText (id);
row.setOnClickListener (new View.OnClickListener () {
@Override
public void onClick(View v) {
Intent intent = new Intent (getActivity (), ChatRoom.class);
intent.putExtra ("group_name", id);
startActivity (intent);
}
});
registerForContextMenu (row);
return row;
}
}
但它仍然没有更新..:(
更新:Listview 在这种情况下是如此错误。然后我就改成Recyclerview了。现在一切都很顺利。
最佳答案
这是因为您正在创建新的适配器实例，而不是更新在 list/recyclerview 上设置的现有适配器上的数据。
private ContactListAdapter mAdatper;
public void addGroupAdapter() {
Firebase jsonurl = new Firebase("firebase url");
jsonurl.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
try {
Log.i("Response Array fire",new JSONArray(dataSnapshot.getValue(String.class)).toString());
if (!adapted){
mAdatper = new ContactListAdapter(getContext(),dataSnapshot);
chatLists.setAdapter(mAdapter);
adapted = true;
}else {
Log.i("update",dataSnapshot.getValue(String.class));
mAdatper.setContactList(dataSnapshot);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
}
在您的适配器中，添加 setter 方法。
public void setContactList(DataSnapshot dataSnapshot) {
// set contactList here
notifyDataSetChanged();
}
希望对您有帮助。
关于java - 更新 ListView 不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43591955/