Не отображаются виджеты в окне

// main.cpp
#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

// mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui/QMainWindow>
class QPushButton;
class QLineEdit;
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
private:
    QPushButton *calc;
    QLineEdit *num1e;
    QLineEdit *num2e;
    QLineEdit *result;
 
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
};
 
#endif // MAINWINDOW_H

// mainwindow.cpp
#include "mainwindow.h"
#include <QtGui>
 
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    result=new QLineEdit;
    num1e=new QLineEdit;
    num2e=new QLineEdit;
    calc=new QPushButton(tr("Calc"));
    QVBoxLayout *LayoutL=new QVBoxLayout;
    LayoutL->addWidget(num1e);
    LayoutL->addWidget(num2e);
    LayoutL->addWidget(calc);
    QHBoxLayout *HLayoutL=new QHBoxLayout;
    HLayoutL->addLayout(LayoutL);
    HLayoutL->addWidget(result);
    setLayout(HLayoutL);
    setWindowTitle(tr("Simple numbers"));
}
 
MainWindow::~MainWindow()
{
 
}

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui>
 
class MainWindow:public QMainWindow
{
Q_OBJECT
 
public:
    MainWindow();
 
private:
 
    QWidget *centralWidget ;
    QWidget *layoutVW ;
    QVBoxLayout *layoutV ;
    QHBoxLayout *layoutH ;
    QPushButton *button ;
 
    QLineEdit *line1 ;
    QLineEdit *line2 ;
    QLineEdit *line3 ;
 
};
 
#endif // MAINWINDOW_H
 
#include <QtGui>
#include "mainwindow.h"
 
MainWindow::MainWindow()
{
 
    centralWidget = new QWidget (this) ;
    centralWidget->resize(2000,2000);
    layoutVW = new QWidget ( centralWidget );
    layoutV = new QVBoxLayout ( layoutVW ) ;
    layoutH = new QHBoxLayout ( ) ;
 
    line1 = new QLineEdit ;
    line2 = new QLineEdit ;
    line3 = new QLineEdit ;
    button = new QPushButton ;
 
    layoutV->addWidget (line2) ;
    layoutV->addWidget (line3) ;
    layoutV->addLayout ( layoutH ) ;
    line2->setText("2") ;
 
    layoutH->addWidget ( button ) ;
    layoutH->addWidget ( line1 ) ;
    line1->setText("1") ;
 
}