qt一个窗体怎样调用另一个窗体的控件
form1里面就一个按钮（pushButton）；
form2里面有 label，
当点击pushButton后在label现实图像

dialog1.h
#define DIALOG1_H

#include <QDialog>
#include "dialog2.h"


namespace Ui {
class Dialog1;
}

class Dialog1 : public QDialog{
Q_OBJECT
public:
Dialog1(QWidget *parent = 0);
~Dialog1();

protected:
void changeEvent(QEvent *e);

private:
Ui::Dialog1 *uii;


};

#endif // DIALOG1_H

dialog2.h
#define DIALOG2_H

#include <QDialog>
#include "dialog1.h"
#include "ui_dialog1.h"

namespace Ui {
class Dialog2;

}

class Dialog2 : public QDialog {
Q_OBJECT
public:
Dialog2(QWidget *parent = 0);
~Dialog2();

protected:
void changeEvent(QEvent *e);

private:
Ui::Dialog2 *ui;
Ui_Dialog1 *w2;

private slots:
void on_pushButton_clicked();
};

#endif // DIALOG2_H

dialog1.cpp
#include "dialog1.h"
#include "ui_dialog1.h"


Dialog1::Dialog1(QWidget *parent) :
QDialog(parent),
uii(new Ui::Dialog1)
{
uii->setupUi(this);
}

Dialog1::~Dialog1()
{
delete uii;
}

void Dialog1::changeEvent(QEvent *e)
{
QDialog::changeEvent(e);
switch (e->type()) {
case QEvent::LanguageChange:
uii->retranslateUi(this);
break;
default:
break;
}
}

dialog2.cpp
#include "dialog2.h"
#include "ui_dialog2.h"
#include "ui_dialog1.h"

Dialog2::Dialog2(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog2)
{
ui->setupUi(this);

}

Dialog2::~Dialog2()
{
delete ui;
}

void Dialog2::changeEvent(QEvent *e)
{
QDialog::changeEvent(e);
switch (e->type()) {
case QEvent::LanguageChange:
ui->retranslateUi(this);
break;
default:
break;
}
}

void Dialog2::on_pushButton_clicked()
{

w2->label_2->setText("ss");
}
当点击按钮后，会出现The program has unexpectedly finished.（程序异常结束）
问下应该怎样解决

[解决办法]
当点击按钮后，会出现The program has unexpectedly finished.（程序异常结束）
问下应该怎样解决

answer：
在Dialog2类中：
Ui_Dialog1 *w2; //此变量并没有new 对象

所以在
w2->label_2->setText("ss");//出现异常