Error adding new data to ListView using ArrayAdapter

Question

I am trying to create a simple chat application. On the chat conversation screen, I use a ListView with an ArrayAdapter to store and display the message, but when I receive or send a new message, the entire last message changes to.

This is my adapter code:

public class MessageAdapter extends ArrayAdapter<Message> { private Context context; private ArrayList<Message> messages; private DatabaseHelper databaseHelper; private Message message; @Override public void add(Message object) { messages.add(object); super.add(object); } public MessageAdapter(Context context, int textViewResouceId, ArrayList<Message> messages) { super(context, textViewResouceId); this.context = context; this.messages = messages; databaseHelper = DatabaseHelper.getInstance(context); } public int getCount() { return messages.size(); } public Message getItem(int index) { return messages.get(index); } public long getItemId(int position) { return position; } @Override public int getPosition(Message item) { return super.getPosition(item); } @Override public View getView(int position, View convertView, ViewGroup parent) { MessageViewHolder messageViewHolder; if (convertView == null) { LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE); convertView = inflater.inflate(R.layout.chat_item, parent, false); messageViewHolder = new MessageViewHolder(); messageViewHolder.tv_userName = (TextView) convertView.findViewById(R.id.tv_chatName); messageViewHolder.tv_message = (TextView) convertView.findViewById(R.id.tv_messageContent); convertView.setTag(messageViewHolder); } else { messageViewHolder = (MessageViewHolder) convertView.getTag(); } message = messages.get(position); String username = databaseHelper.getUserByUserId(message.getUserId()).getUserName(); if (message.getUserId() == AppConfig.USER_ID) { messageViewHolder.tv_message.setTextColor(Color.parseColor("#0066ff")); messageViewHolder.tv_userName.setTextColor(Color.parseColor("#0066ff")); } else { messageViewHolder.tv_message.setTextColor(Color.parseColor("#000000")); messageViewHolder.tv_userName.setTextColor(Color.parseColor("#000000")); } messageViewHolder.tv_userName.setText(username); messageViewHolder.tv_message.setText(message.getMessage()); return convertView; } static class MessageViewHolder { TextView tv_message; TextView tv_userName; } } 

This is my ListView layout code:

 <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <android.support.design.widget.AppBarLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:theme="@style/AppTheme.AppBarOverlay"> <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" /> </android.support.design.widget.AppBarLayout> <ScrollView android:id="@+id/scroll_chat" android:layout_width="match_parent" android:layout_height="380dp"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent"> <ListView android:id="@+id/listMessage" android:layout_width="match_parent" android:layout_height="380dp" android:background="@null" android:divider="@null" android:stackFromBottom="true" android:drawSelectorOnTop="false" android:transcriptMode="alwaysScroll" /> </LinearLayout> </ScrollView> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal" android:weightSum="1"> <EditText android:id="@+id/txt_chat" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_weight="0.92" /> <Button android:id="@+id/btn_send" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_marginLeft="30dp" android:text="@string/btn_send" /> </LinearLayout> </LinearLayout> 

And this is an error when sending two messages (the same error occurs when I receive a message)

I think the problem is how to set the data in the View, but I cannot solve it. Can anyone help me solve this problem.

This is the chat screen when I close and reopen an action. He showed the correct message.

This is the Chatactivity code:

 public class ChatActivity extends AppCompatActivity implements View.OnClickListener { private Button btn_send; private static EditText txt_chat; private String registId; private Bundle bundle; private String chatTitle; private MessageSender mgsSender; private int userId; private DatabaseHelper databaseHelper; private TimeUtil timeUtil; private MessageAdapter messageAdapter; private ListView lv_message; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_chat); Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(toolbar); if (getSupportActionBar() != null) { getSupportActionBar().setDisplayHomeAsUpEnabled(true); } btn_send = (Button) findViewById(R.id.btn_send); txt_chat = (EditText) findViewById(R.id.txt_chat); lv_message = (ListView) findViewById(R.id.listMessage); // lv_message.setTranscriptMode(ListView.TRANSCRIPT_MODE_ALWAYS_SCROLL); timeUtil = new TimeUtil(); databaseHelper = DatabaseHelper.getInstance(getApplicationContext()); btn_send.setOnClickListener(this); bundle = getIntent().getExtras(); chatTitle = bundle.getString("titleName"); if (getIntent().getBundleExtra("INFO") != null) { chatTitle = getIntent().getBundleExtra("INFO").getString("name"); this.setTitle(chatTitle); } else { this.setTitle(chatTitle); } registId = bundle.getString("regId"); userId = databaseHelper.getUser(chatTitle).getUserId(); List<Message> messages = databaseHelper.getMessges(AppConfig.USER_ID, databaseHelper.getUser(chatTitle).getUserId()); messageAdapter = new MessageAdapter(getApplicationContext(), R.layout.chat_item, (ArrayList<Message>) messages); LocalBroadcastManager.getInstance(this).registerReceiver(onNotice, new IntentFilter("Msg")); if (messages.size() > 0) lv_message.setAdapter(messageAdapter); } private BroadcastReceiver onNotice = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { String message = intent.getStringExtra("message"); try { Message messageObj = Message.getInstance(); messageObj.setMessage(message); messageObj.setUserId(userId); messageObj.setSender_id(AppConfig.USER_ID); messageObj.setExpiresTime(timeUtil.formatDateTime(timeUtil.getCurrentTime())); messageAdapter.add(messageObj); } catch (ParseException e) { e.printStackTrace(); } messageAdapter.notifyDataSetChanged(); } }; @Override public void onBackPressed() { super.onBackPressed(); finish(); } @Override protected void onDestroy() { LocalBroadcastManager.getInstance(this).unregisterReceiver(onNotice); super.onDestroy(); } private static MessageSenderContent createMegContent(String regId, String title) { String message = txt_chat.getText().toString(); MessageSenderContent mgsContent = new MessageSenderContent(); mgsContent.addRegId(regId); mgsContent.createData(title, message); return mgsContent; } @Override public void onClick(View v) { switch (v.getId()) { case R.id.btn_send: String message = txt_chat.getText().toString(); databaseHelper = DatabaseHelper.getInstance(getApplicationContext()); mgsSender = new MessageSender(); new AsyncTask<Void, Void, Void>() { @Override protected Void doInBackground(Void... params) { MessageSenderContent mgsContent = createMegContent(registId, AppConfig.USER_NAME); mgsSender.sendPost(mgsContent); return null; } }.execute(); databaseHelper.addMessage(message, timeUtil.getCurrentTime(), userId, AppConfig.USER_ID); txt_chat.setText(""); try { Message messageObj = Message.getInstance(); messageObj.setMessage(message); messageObj.setUserId(AppConfig.USER_ID); messageObj.setSender_id(userId); messageObj.setExpiresTime(timeUtil.formatDateTime(timeUtil.getCurrentTime())); messageAdapter.add(messageObj); } catch (ParseException e) { e.printStackTrace(); } messageAdapter.notifyDataSetChanged(); break; } } } 

Answer 1

In your ChatActivity . In onClickEvent
Try to change

 Message messageObj = Message.getInstance(); 

to

 Message messageObj = new Message(); 

You can read more about Singleton Pattern here.