添加新的ListView项目的问题

Question

I am facing a problem with ListView in Android. I tried to make a simulation of chat application with some dummy data (first few messages in conversation added in Java code).

After dummy messages, the user may append message list by entering one explicitly. I used boolean to separate sent messages from received, but somehow messages I send to the list appears as received message until I add a new message.

The first one I added appears like a sent message, but the new one appears as received and so on... I guess it has something with focus but cannot understand well. There are screenshots of problem and source code.

adapter class

public class MessageAdapter extends BaseAdapter {
    private Context mContext;
    private ArrayList<MessageClass> messagesThreadView;
    private MessageClass msg;
    public MessageAdapter(Context context) {
        this.mContext = context;
        this.messagesThreadView = new ArrayList<MessageClass>();
    }

public void addMessageToThread(MessageClass messageClass) {
    this.messagesThreadView.add(messageClass);
    notifyDataSetChanged();
}

public void removeMessageFromThread (int position) {
    this.messagesThreadView.remove(position);
    notifyDataSetChanged();
}

@Override
public int getCount() {
    return messagesThreadView.size();
}

@Override
public Object getItem(int i) {
    return messagesThreadView.get(i);
}

@Override
public long getItemId(int i) {
    return i;
}

@Override
public View getView(int i, View view, ViewGroup viewGroup) {
    View view1 = view;
    MessageClass tempMessageClass = (MessageClass) getItem(i);

    if (view1==null) {
        LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view1 = inflater.inflate(R.layout.thread_message_layout, null);
        ViewHolder viewHolder = new ViewHolder();
        viewHolder.message = (TextView) view1.findViewById(R.id.messageContent);
        view1.setTag(viewHolder);
    }

    ViewHolder vh = new ViewHolder();
    vh.message=view1.findViewById(R.id.messageContent);
    if (tempMessageClass.isSentFromMyDevice()) {
        vh.message.setPadding(20,20,50,20);
        vh.message.setGravity(Gravity.END);
    //            vh.message.setTextColor(Color.argb(255, 253,227,17));           
    // converted from colors.xml
        vh.message.setTextColor(Color.argb(255,255,255,255));
        vh.message.setBackgroundColor(Color.argb(255, 114,114,114));    // --||--
        notifyDataSetChanged();
    } else {
        vh.message.setPadding(50,20,20,20);
        vh.message.setGravity(Gravity.START);
        vh.message.setBackgroundColor(Color.argb(175, 253, 227, 17));   // converted from colors.xml @colors/foreground
        notifyDataSetChanged();
    }

    //final ViewHolder viewHolder = (ViewHolder) view1.getTag();
    vh.message.setText(tempMessageClass.text);
    return view1;
}

private class ViewHolder {
    public TextView message = null;
}
}

EDIT: Everything working fine, until I decided to have 2 text colors, one for received messages, second for sent messages. Now after scrolling up-down, received messages text color has been overwritten by sent message text color. Any help?

Answer 1

Add data to adapter first , thn call

notifyDataSetChanged 

On your adapter

Answer 2

Thanks people, changes accepted, and works almost perfect. There is no more left-right moving unexpectedly. Now I have one more problem. After incoming messages, reach out of visibility field (when I add new message, focus is always on the newest, and old ones goes on the top). Messages that moved up somehow lose their text, and I only can see background color. After few more messages added, text is shown. It's not working predictably.

New adapter code is here:

    public View getView(int i, View view, ViewGroup viewGroup) {
    View view1 = view;
    MessageUserDefinedClass tempMessageUserDefinedClass = (MessageUserDefinedClass) getItem(i);

    if (view1 == null) {
        LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view1 = inflater.inflate(R.layout.thread_message_layout, null);
        ViewHolder viewHolder = new ViewHolder();
        viewHolder.message = (TextView) view1.findViewById(R.id.messageContent);
        view1.setTag(viewHolder);
    }
    ViewHolder vh = new ViewHolder();
    view1.setTag(vh);
    if (tempMessageUserDefinedClass.isSentFromMyDevice()) {
        vh.message.setPadding(0, 0, 20, 0);
        vh.message.setGravity(Gravity.END);
        vh.message.setTextColor(Color.argb(255, 253, 227, 17));
        vh.message.setBackgroundColor(Color.argb(255, 114, 114, 114));
        notifyDataSetChanged();
    } else {
        vh.message.setPadding(20, 0, 0, 0);
        vh.message.setGravity(Gravity.START);
        vh.message.setBackgroundColor(Color.argb(255, 253, 227, 17)); // converted from colors.xml @colors/foreground
        notifyDataSetChanged();
    }

    final ViewHolder viewHolder = (ViewHolder) view1.getTag();
    viewHolder.message.setText(tempMessageUserDefinedClass.text);
    return view1;
}

I guess it has something with new ViewHolder I added, because first one is created in if statement. Thanks a lot. :)