Android - Saving Objects to List of Object

Question

I am learning how to retrieve data stored in Parse.I am able to retrieve data from parse and bind it to simple ListView. Now I am trying to mock a simple chat app. I have two column in my parse class to store senders name and Chat message. I have made a Custom ListView to show the senders name and message as shown below

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/UserNameTxt"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5sp"
    android:textColor="@color/material_blue_grey_900"
    android:textSize="15sp" />
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/UserMessageTxt"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5sp"
    android:textColor="@color/material_blue_grey_900"
    android:textSize="25sp" />
</LinearLayout>

And An Adapter Class to bind the data

public class ChatAdapter extends ArrayAdapter<Chat> {
Context context;
int layoutResourceId;
Chat data[] = null;
public ChatAdapter(Context context, int resource, Chat[] objects) {
    super(context, resource, objects);
    this.layoutResourceId=resource;
    this.context=context;
    this.data=objects;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View row=convertView;
    ChatHolder holder=null;
    if(row==null)
    {
        LayoutInflater inflater=((Activity)context).getLayoutInflater();
        row=inflater.inflate(layoutResourceId,parent,false);
        holder= new ChatHolder();
        holder.UserName=(TextView)row.findViewById(R.id.UserNameTxt);
        holder.UserMessage=(TextView)row.findViewById(R.id.UserMessageTxt);
        row.setTag(holder);
    }
    else
    {
        holder=(ChatHolder)row.getTag();
    }
    Chat chat=data[position];
    holder.UserName.setText(Chat.UserName);
    holder.UserMessage.setText(Chat.UserMessage);
    return row;
}
static class ChatHolder
{
    TextView UserName;
    TextView UserMessage;
}
}

And the chat class is

public class Chat {
public static String UserName;
public static String UserMessage;
public Chat()
{
    super();
}
public Chat(String _UserName,String _UserMessage)
{
    super();
    UserName=_UserName;
    UserMessage=_UserMessage;
}
public String getName()
{
    return UserName;
}
}

Code for Main Activity is (I have just included the Important parts)

List<Chat> chatData=new ArrayList<Chat>();

@Override
protected Void doInBackground(Void... params) {
        ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
                "Chat");
        try {
            ob = query.find();
        } catch (ParseException e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

@Override
protected void onPostExecute(Void result) {
        Chat c;
        listview = (ListView) findViewById(R.id.listView);
        for (ParseObject country : ob) {
            chatData.add(new Chat((String) country.get("Sender"),(String) country.get("ChatMessage")));
        }
        String name01=chatData.get(0).getName(); //for debugging
        String name02=chatData.get(1).getName(); //for debugging
        String name03=chatData.get(2).getName(); //for debugging

        Chat chatArray[]=chatData.toArray(new Chat[chatData.size()]);

        String name=chatArray[0].getName(); //for debugging
        String name1=chatArray[1].getName(); //for debugging
        String name2=chatArray[2].getName(); //for debugging

        ChatAdapter cAdapter=new ChatAdapter(MainActivity.this,R.layout.listview_item,chatArray);

        listview.setAdapter(cAdapter);
        mProgressDialog.dismiss();
    }

Screenshot of the output https://i.sstatic.net/bxnto.png

I have three rows of data in my Parse class. As an output I am getting the last inserted row only three times. Here is the screenshot of debugging Windows https://i.sstatic.net/l7CAs.png

Inside for loop I am getting the proper values from the parse but After adding it to the chatData list something wrong happens.

This is my first question here. I am extremely sorry for the big post and if I am not clear with the question. Thank You

Answer 1

It seems to me that static UserName and UserMessage in your Chat class are the cause of your problem. Change them to

public String UserName;    //from  public static String UserName;
public String UserMessage; //from  public static String UserMessage;

and also change this part in your adapter:

holder.UserName.setText(chat.UserName);       // from Chat.UserName
holder.UserMessage.setText(chat.UserMessage); // from Chat.UserMessage