findChild never displays textBrowser - c++

Question

I trying to display some text to a textbrowser via: FindChild and it never displays it in the textbrowswer any help would be helpfull..
Here is my mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
namespace Ui
{
class MainWindow;
class TestWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
static MainWindow* GetInstance(QWidget* parent = 0);
signals:
public slots:
void on_pushButton_3_clicked();
void MainWindow_TextBrowser_String(const QString & newText);
private:
Ui::MainWindow *ui;
static MainWindow* mainInstance;
};
Here is my mainwindow.cpp
// Constructor
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
// Destructor
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_3_clicked()
{
TestWindow mwindow;
mwindow.start();
}
MainWindow* MainWindow::mainInstance = 0;
MainWindow* MainWindow::GetInstance(QWidget *parent)
{
if (mainInstance == NULL)
{
mainInstance = new MainWindow(parent);
}
return mainInstance;
}
void MainWindow::MainWindow_TextBrowser_String(const QString & newText)
{
QString TextBrowser_String = QString(newText);
ui->textBrowser->append(TextBrowser_String);
}
I create the testwindow object in the pushbutton send the start function to call the findchild window to send a string to the textbrowser window
Here is my testwindow.cpp
void testwindow::start()
{
// Create a new mainwindow on the heap.
MainWindow* instance = MainWindow::GetInstance();
// Or I can call
// MainWindow instance; then point to findchild
QString Test_Window_String = QStringLiteral("Test Window String");
instance->findChild<QTextBrowser*>("textBrowser")->append(Test_Window_String);
}
I understand that you can use a singal and slot and simply just create a signal that sends the string to the append textbrowser
void testwindow::singalandslot()
{
MainWindow* instance = MainWindow::GetInstance();
connect(this, SIGNAL(TextBrowswer_String(const QString &)), instance , SLOT(MainWindow_TextBrowser_String(QString &)));
}
void testwindow::fireSignal()
{
emit TextBrowswer_String("sender is sending to receiver.");
}
Even with a signal or FindChild it seems that the object is already deleted or i'm doing something wrong.

Answer 1

Can you please share your Ui::MainWindow Class and setupUi implementation to get a clear view?
Hope you have created the instance for QTextBrowser* inside setupUi or in the constructor.
With the below setupUi implementation, both ur usecases are working.
namespace Ui
{
class MainWindow: public QWidget
{
Q_OBJECT
public:
QTextBrowser* textBrowser;
void setupUi(QWidget* parent)
{
setParent(parent);
textBrowser = new QTextBrowser(parent);
textBrowser->setObjectName("textBrowser");
textBrowser->setText("Hello");
}
};
}