Android聊天應用程序：消息適配器不正確更新列表視圖中的項目

Question

這是我在Stack Overflow中的第一個問題，我一直在Android上構建一個簡單的聊天應用程序，它從在線數據庫加載聊天記錄，它將會使用自定義消息適配器以列表視圖顯示。

這裏是程序的當前狀態：

Demo

然而，列表項的佈局不下來數組列表中的第六聊天消息後正確的，下面所有的聊天消息重複前6條消息的佈局。

這裏是我的適配器代碼：

public class messageAdapter extends ArrayAdapter<chatMessage> { 

private Activity activity; 
private List<chatMessage> messages; 

public messageAdapter(Activity context, int resource, List<chatMessage> objects) { 
    super(context, resource, objects); 
    this.activity = context; 
    this.messages = objects; 
} 

@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
    ViewHolder holder; 
    LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE); 

    int layoutResource = 0; // determined by view type 
    chatMessage chatMessage = getItem(position); 
    int viewType = getItemViewType(position); 

    if (chatMessage.isMine()) { 
     layoutResource = R.layout.chat_bubble_right; 
    } else { 
     layoutResource = R.layout.chat_bubble_left; 
    } 

    if (convertView != null) { 
     holder = (ViewHolder) convertView.getTag(); 
    } else { 
     convertView = inflater.inflate(layoutResource, parent, false); 
     holder = new ViewHolder(convertView); 
     convertView.setTag(holder); 
     Log.d("ViewID", "generated"); 
    } 

    //set message content 
    holder.message.setText(chatMessage.getContent()); 

    return convertView; 
} 

@Override 
public int getViewTypeCount() { 
    // return the total number of view types. this value should never change 
    // at runtime 
    return 2; 
} 

@Override 
public int getItemViewType(int position) { 
    // return a value between 0 and (getViewTypeCount - 1) 
    return position % 2; 
} 

private class ViewHolder { 
    private TextView message; 

    public ViewHolder(View v) { 
     message = (TextView) v.findViewById(R.id.txt_msg); 
    } 
} 

這是我的聊天消息加載到數組列表的方法：

private class getChatHistory extends AsyncTask<DBConnection,Long,JSONArray> { 
    @Override 
    protected JSONArray doInBackground(DBConnection... params) { 
     return params[0].getChatHistory(userID); 
    } 

    @Override 
    protected void onPostExecute(JSONArray jsonArray) { 

     chatData = jsonArray; 

     if (chatData != null) 
     { 
      for (int i = 0; i < chatData.length(); i++) 
      { 
       JSONObject currentItem = null; 

       try 
       { 
        currentItem = chatData.getJSONObject(i); 
        int msgID = currentItem.getInt("MessageID"); 
        String currentText = currentItem.getString("MessageContent"); 
        int senderID = currentItem.getInt("SenderID"); 
        int receiverID = currentItem.getInt("ReceiverID"); 
        chatMessage currentMessage = new chatMessage(currentText, senderID, userID); 
        Log.d("Is Mine", Boolean.toString(currentMessage.isMine())); 
        messageHistory.add(currentMessage); 
        DBAdapter.notifyDataSetChanged(); 

       } catch (JSONException e) { 
        e.printStackTrace(); 
       } 
      } 
     } 
    } 
} 

這裏是我從所獲得的JSONArray我跑的PHP文件：

[{"MessageID":"1","SenderID":"1","ReceiverID":"8","Duration":"2.4","MessageContent":"agnblean liajiaj vliwv fla","MessageLength":"26","Status":"received","Date":"2016-04-04 14:00:00"}, 
{"MessageID":"2","SenderID":"8","ReceiverID":"1","Duration":"3.1","MessageContent":"akwuehrgeubwfcofawve","MessageLength":"20","Status":"received","Date":"2016-04-04 17:00:00"}, 
{"MessageID":"3","SenderID":"8","ReceiverID":"1","Duration":"3.1","MessageContent":"akwuehrgeubwfjurawve","MessageLength":"20","Status":"received","Date":"2016-04-04 17:00:05"}, 
{"MessageID":"4","SenderID":"8","ReceiverID":"1","Duration":"3.1","MessageContent":"akwuehrgeubwalwrawve","MessageLength":"20","Status":"received","Date":"2016-04-04 17:00:10"}, 
{"MessageID":"5","SenderID":"1","ReceiverID":"8","Duration":"3.1","MessageContent":"akwuehrgeubwalwrawve","MessageLength":"20","Status":"received","Date":"2016-04-04 17:01:10"}, 
{"MessageID":"8","SenderID":"1","ReceiverID":"8","Duration":"4.6","MessageContent":"vsjkgkgredjegwhkaga","MessageLength":"23","Status":"received","Date":"2016-04-05 05:00:00"}, 
{"MessageID":"9","SenderID":"8","ReceiverID":"1","Duration":"5.2","MessageContent":"agrlanwligna","MessageLength":"21","Status":"received","Date":"2016-04-06 00:00:00"}, 
{"MessageID":"10","SenderID":"8","ReceiverID":"1","Duration":"7.2","MessageContent":"akewgaughurawaarg","MessageLength":"12","Status":"received","Date":"2016-04-12 00:00:00"}, 
{"MessageID":"11","SenderID":"1","ReceiverID":"8","Duration":"7.2","MessageContent":"wgkakjrgnjange","MessageLength":"41","Status":"received","Date":"2016-04-15 00:00:00"}, 
{"MessageID":"12","SenderID":"1","ReceiverID":"8","Duration":"4.67","MessageContent":"yikes","MessageLength":"5","Status":"received","Date":"2016-04-21 00:00:00"}, 
{"MessageID":"13","SenderID":"8","ReceiverID":"1","Duration":"8.2","MessageContent":"iobanoine","MessageLength":"4","Status":"received","Date":"2016-04-30 00:00:00"}] 

所以我認爲這會產生正確的佈局聊天曆史，其中活性用戶是用戶ID = 1，並且所有與發送者ID的消息= 1應在列表視圖的右手側，而是我得到這個：

screenshot

這是列表視圖中第5-8個元素的截圖，但第7個元素位於右側而不是左側，後面的元素繼續重複之前的6元素的模式。我檢查了轉換視圖的日誌，它只顯示了6次，是否與這個錯誤有關呢？我該如何解決適配器沒有正確定位列表項資源的問題？

EDIT：我已經改變了getItemViewType（）的覆蓋到這個

@Override 
public int getItemViewType(int position) { 
    chatMessage chatMessage = getItem(position); 
    if (chatMessage.isMine()) { 
     return 0; 
    } else { 
     return 1; 
    } 
} 

我也已刪除了重寫方法爲getViewTypeCount，並在getView改變條件的位（）方法：

int viewType = getItemViewType(position); 

    if (viewType==0) { 
     layoutResource = R.layout.chat_bubble_right; 
    } else { 
     layoutResource = R.layout.chat_bubble_left; 
    } 

現在聊天消息列表按正常順序排列到第8個元素，然後順序再次變得不正確。

EDIT 2

我有跟蹤日誌列表項的產生（即新項目）的數量，這是結果向下滾動到列表視圖底部後，我得到：

04-06 19:23:54.894 11202-11202/com.example.user.normalinterface D/ViewID: generated 
04-06 19:23:54.907 11202-11202/com.example.user.normalinterface D/ViewID: generated 
04-06 19:23:54.912 11202-11202/com.example.user.normalinterface D/ViewID: generated 
04-06 19:23:54.914 11202-11202/com.example.user.normalinterface D/ViewID: generated 
04-06 19:23:56.850 11202-11202/com.example.user.normalinterface D/ViewID: generated 

這是在反正與我的問題？它看到列表視圖中的所有後續記錄都從列表中的前5個項目重複該模式。

Answer 1

我認爲它來自於getViewTypeCount()方法。在這裏你說你有兩種不同的佈局。用方法getItemViewType()你說，不同的類型是2條消息中的一條。但是你不要使用getView方法中的類型。

顯然，你不需要這些2種類型，所以我建議你只是刪除了2種方法： getViewTypeCount()和 getItemViewType()

我不認爲你需要他們在你的情況。

編輯： 你實際上需要這些方法，但你嚴重凌駕getItemViewType。

@Override 
public int getItemViewType(int position) { 
    chatMessage chatMessage = getItem(position); 
    if (chatMessage.isMine()) { 
     return 0; 
    } else { 
     return 1; 
    } 
} 

Answer 2

以我的經驗，但未必是有關這一點，你需要調用notifyDataSetChanged（）的適配器，所以成立了一個名爲refreshData方法的適配器是這樣的：

public void refreshData(ArrayList<yourList> data) { 
    mValues.clear(); 
    mValues.addAll(data); 
    notifyDataSetChanged(); 
} 

並致電您的活動：

mAdapter.refreshData(newData) 

以新數據爲參數。

此外，請確保您引用適配器類正確，所以嘗試添加到您的類的開頭：

private final DBAdapter mAdapter; 

然後在getChaHistory補充：

mAdapter = DBAdapter 

的想法是，你有正確引用的適配器的句柄。請注意，您現在調用mAdapter.refreshData（newData）而不是DBAdapter.refreshData（newdata）的前一個答案的更改。真的，我認爲你應該把適配器傳給班上，這正是我所做的，但你可以試試這種方式，看看你怎麼樣？

Answer 3

這會正常工作，但不會一樣快。如果「isMine（）」爲true，那麼它決定實例化哪個佈局取決於值。如果「isMine（）」爲true，那麼包含右對齊的TextView的佈局被實例化，否則其他佈局被實例化（TextView左對齊）

@Override 
public View getView(int position, View convertView, ViewGroup parent){ 

    if(messages.get(position).isMine()){ 
     item = ((Activity)context).getLayoutInflater().inflate(R.layout.chat_bubble_right,null); 
    } 
    else{ 
     item = ((Activity)context).getLayoutInflater().inflate(R.layout.chat_bubble_left,null); 
    } 
    // set the text in the view. 
    ((TextView) item.findViewById(R.id.chat_text)).setText(data.get(position).getMessage()); 
    return item; 
} 

的chat_text id表示TextView的實例化佈局內（兩個佈局包含具有ID chat_text一個TextView）
我用這個谷歌IO事件作爲一種資源：。
https://www.youtube.com/watch?v=wDBM6wVEO70