Qt - Add item from a second window to ListWidget in MainWindow

Question

I have a QDialog where I can enter a Text and add it to a ListWidget inside the MainWindow after I clicked OK. Therefore I created a Method in the MainWindow class AddMessageToList(message) where the entered message is added to the ListWidget. I call the Method inside my ListAdder class (2nd Window). However nothing gets added to the ListWidget.

Here are the codes:

listadder.cpp

#include "listadder.h"
#include "ui_listadder.h"
#include "mainwindow.h"
#include "ui_mainwindow.h"

ListAdder::ListAdder(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::ListAdder)
{
    ui->setupUi(this);
}

ListAdder::~ListAdder()
{
    delete ui;
}

void ListAdder::on_buttonBox_accepted()
{
    MainWindow mw;
    QString message = ui->lnText->text();
    mw.AddMessageToList(message);
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "listadder.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pbt_Edit_clicked()
{
    ListAdder lsadd;
    lsadd.exec();
}

void MainWindow::AddMessageToList(QString message)
{
    ui->lsItems->addItem(message);
}

Answer 1

Fixed it!

I created a QString method GetMessage() where I return the entered text. In the MainWindow I call the method and add the text to the ListWidget.

listadder.cpp:

#include "listadder.h"
#include "ui_listadder.h"
#include "mainwindow.h"
#include "ui_mainwindow.h"

ListAdder::ListAdder(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::ListAdder)
{
    ui->setupUi(this);
}

ListAdder::~ListAdder()
{
    delete ui;
}

QString ListAdder::GetMessage()
{
    QString message = ui->lnText->text();
    return message;
}

void ListAdder::on_buttonBox_accepted()
{
    
}

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "listadder.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pbt_Edit_clicked()
{
    ListAdder lsadd;
    lsadd.exec();
    ui->lsItems->addItem(lsadd.GetMessage());
}