如何获取arraylist中的所有项目并将其显示在列表视图中

Question

public class ChatBubbleActivity extends AppCompatActivity {
private static final String TAG = "ChatActivity";
Toolbar toolbar;
TextView tv_name;
List<ListData> dataList;
int user_id;
int msg_type = 1;
DatabaseHelper databaseHelper;
private ListView listView;
private EditText chatText;
private ImageButton buttonSend;
private String name, message, time;
private ChatArrayAdapter chatArrayAdapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_chat);
    name = getIntent().getStringExtra("name");
    user_id = getIntent().getIntExtra("user_id", 0);
    databaseHelper = new DatabaseHelper(this);

    toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_back);
    toolbar.setTitleTextColor(getResources().getColor(R.color.white));
    toolbar.setSubtitleTextColor(getResources().getColor(R.color.white));
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    receiveMessage();
    tv_name = findViewById(R.id.tv_name);
    buttonSend = findViewById(R.id.buttonSend);
    listView = findViewById(R.id.listView1);
    chatText = findViewById(R.id.chatText);
    listView.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
    listView.setAdapter(chatArrayAdapter);
    chatArrayAdapter.registerDataSetObserver(new DataSetObserver() {
        @Override
        public void onChanged() {
            super.onChanged();
            listView.setSelection(chatArrayAdapter.getCount() - 1);
        }
    });
    tv_name.setText(name);
}

private void receiveMessage() {
    dataList = new ArrayList<>();
    dataList = databaseHelper.getSingleUserMsg(user_id);
    for (int i = 0; i < dataList.size(); i++) {
        ListData listData=dataList.get(i);
        message = listData.getMessage();
        time = listData.getCreated_at();
        msg_type = listData.getMsg_type();
        Log.d("Message",message);
        Date dateTime = null;
        try {
            dateTime = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss a").parse(time);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(dateTime);
        DateFormat timeFormatter = new SimpleDateFormat("h:mm a");
        int layout_resource;
        if (dataList.get(i).getMsg_type() == 0) {
            layout_resource = R.layout.item_chat_left;
        } else {
            layout_resource = R.layout.item_chat_right;
        }
        chatArrayAdapter = new ChatArrayAdapter(getApplicationContext(), layout_resource, dataList, msg_type);
        chatArrayAdapter.add(new ChatMessage(message, timeFormatter.format(dateTime)));
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.conversation_menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            onBackPressed();
            return true;
    }
    return super.onOptionsItemSelected(item);
}

}

This is my Chat screen activity.I retrieve the values from the sqlite database and store it in a arraylist. When i try to get the data from the arraylist and show in the listview it also shows last item in the arraylist. How to get all the items in arraylist and load it in the listview. How to do this? Please help to do this

public List<ListData> getSingleUserMsg(int user_id) {
    List<ListData> listData = new ArrayList<>();
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery("select message,created_at,msg_type from " + TABLE_MSG + " WHERE " + USER_ID + " = " + user_id + " ORDER BY " + CREATED_AT + ";", null);
    ListData listData1;
    while (cursor.moveToNext()) {
        listData1 = new ListData();
        String message = cursor.getString(cursor.getColumnIndexOrThrow("message"));
        String created_at = cursor.getString(cursor.getColumnIndexOrThrow("created_at"));
        String msg_type = cursor.getString(cursor.getColumnIndexOrThrow("msg_type"));
        listData1.setMessage(message);
        listData1.setMsg_type(Integer.parseInt(msg_type));
        listData1.setCreated_at(created_at);
        listData.add(listData1);
    }
    return listData;
}

The above code is the method of database helper.

Answer 1

Write this lines outside your for loop.

chatArrayAdapter = new ChatArrayAdapter(getApplicationContext(), layout_resource, dataList, msg_type);
        chatArrayAdapter.add(new ChatMessage(message, timeFormatter.format(dateTime)));

Answer 2

Add adapter code in outside of the loop and refresh the list.Because your calling receiveMessage() after that only your setting adapter that is the issue

1.Main Activity call method like this after listView initialization call receiveMessage()

tv_name = findViewById(R.id.tv_name);
buttonSend = findViewById(R.id.buttonSend);
listView = findViewById(R.id.listView1);
chatText = findViewById(R.id.chatText);
listView.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
receiveMessage();

  private void receiveMessage() {
    dataList = new ArrayList<>();
    dataList = databaseHelper.getSingleUserMsg(user_id);
    for (int i = 0; i < dataList.size(); i++) {
        ListData listData=dataList.get(i);
        message = listData.getMessage();
        time = listData.getCreated_at();
        msg_type = listData.getMsg_type();
        Log.d("Message",message);
        Date dateTime = null;
        try {
            dateTime = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss a").parse(time);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(dateTime);
        DateFormat timeFormatter = new SimpleDateFormat("h:mm a");
        int layout_resource;
        if (dataList.get(i).getMsg_type() == 0) {
            layout_resource = R.layout.item_chat_left;
        } else {
            layout_resource = R.layout.item_chat_right;
        }

    }
    chatArrayAdapter = new ChatArrayAdapter(getApplicationContext(), layout_resource, dataList, msg_type);
    chatArrayAdapter.add(new ChatMessage(message, timeFormatter.format(dateTime)));
    listView.setAdapter(chatArrayAdapter);
}