QMainWindow Issue

[QT_QT_QT]

I have an issue over here, this is regarding to main window . Supposedly in the main window has a push button and that button will lead us to a new window . In other words, at the moment the user pressed the button , the user will see a new main window , and the previous window will be close. Below code keep providing these error : Ui::newwindow:no appropriate default constructor available, use of defined type 'Ui::newwindow' and left of '->setupUI' must point to class/struct/union/generic type;

***MainWindow.h***

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "newwindow.h"
#include <QWidget>

namespace Ui {
class MainWindow;
}


class MainWindow : public QMainWindow
{
     Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private slots:
    void on_pushButton_clicked();

    void on_pushButton_2_clicked();

    void on_pushButton_3_clicked();

    void on_pushButton_4_clicked();

    void openNewWindow();

private slots:
    void on_pushButton_5_clicked();

private:
    Ui::MainWindow *ui;
private:
    newwindow *MyNewWindow;


};

#endif // MAINWINDOW_H

***newwindow.h***
#ifndef NEWWINDOW_H
#define NEWWINDOW_H

#include <QMainWindow>

namespace Ui {
    class newwindow;
}

class newwindow : public QMainWindow
{
    Q_OBJECT
public:
    newwindow();
    explicit newwindow(QWidget *parent = 0);
    ~newwindow();
 private:
    Ui::newwindow *ui;
};

#endif // NEWWINDOW_H

***mainwindow.cpp***


#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QByteArray>
#include <QProcess>
#include <Windows.h>
#include <iostream>
#include <string>
#include <cstdlib>
#include <stdlib.h>
#include <QDebug>
#include <QString>
#include <QMessageBox>
#include "newwindow.h"
#include <QWidget>

using namespace std;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->pushButton_5,SIGNAL(click()),this, SLOT (openNewWindow()));
 }


MainWindow::~MainWindow()
{
    delete ui;


}

void MainWindow ::openNewWindow()
{
    MyNewWindow = new newwindow();
    MyNewWindow-> show();
}

void MainWindow::on_pushButton_5_clicked()
{
    openNewWindow();
}

***newwindow.cpp***


#include "newwindow.h"
#include "ui_mainwindow.h"

#include <QMainWindow>


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

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

Some one from here please tell what is problem that i m facing now . please....... I dont understand why i keep getting the error . Thank you

[mrjj]

Did you add this newwindow , via
File->New->Qt->QtDesigner Form Class
and then QMainwindow?

Also having multiple Main Windows is a rare design.
Are you sure this is how u want ? the user will see the window close and new one come.
Like app crashed and restarted.
If you need a design where u have pages ,
the QStackwidget is much better. (IMHO)