单击QT按钮可更改明文外部编辑

我对QT完全陌生。我写了一个小表单，有4个单选按钮、点击按钮和纯文本编辑字段（在QT Creator中）。我的目标是按下按钮，在明文中更改文本（"此处有一些文本"）。不幸的是，我找不到连接按钮和文本字段的正确公式，所以我遇到了一个错误，我还不知道。以下是代码（我省略了GUI XML部分）：

主窗口.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QRadioButton>
#include <QPushButton>
#include <QPlainTextEdit>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
public slots:
    void on_pushButton_clicked();
private:
    Ui::MainWindow *ui;
    QRadioButton radioButton,radioButton_2,radioButton_3,radioButton_4;
    QPushButton pushButton;
    QPlainTextEdit plainTextEdit;
};
#endif // MAINWINDOW_H

main.cpp:

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

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
//#include <QPushButton>
//#include <QPlainTextEdit>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QObject::connect(pushButton,SIGNAL(clicked()),plainTextEdit,SLOT(on_pushButton_clicked()));
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::on_pushButton_clicked()
{
    plainTextEdit.setPlainText("Some text here");
}

以下是错误输出：

/home/user/workspace/ButtonRadio/mainwindow.cpp:-1: In constructor 'MainWindow::MainWindow(QWidget*)':
/home/user/workspace/ButtonRadio/mainwindow.cpp:11: error: no matching function for call to 'MainWindow::connect(QPushButton&, const char*, QPlainTextEdit&, const char*)'
/home/user/workspace/ButtonRadio/mainwindow.cpp:11: candidates are:
/usr/include/qt4/QtCore/qobject.h:204: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/usr/include/qt4/QtCore/qobject.h:204: note:   no known conversion for argument 1 from 'QPushButton' to 'const QObject*'
/usr/include/qt4/QtCore/qobject.h:217: static bool QObject::connect(const QObject*, const QMetaMethod&, const QObject*, const QMetaMethod&, Qt::ConnectionType)
/usr/include/qt4/QtCore/qobject.h:217: note:   no known conversion for argument 1 from 'QPushButton' to 'const QObject*'
/usr/include/qt4/QtCore/qobject.h:337: bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
/usr/include/qt4/QtCore/qobject.h:337: note:   no known conversion for argument 1 from 'QPushButton' to 'const QObject*'

如果我只写

QObject::connect(pushButton,SIGNAL(clicked()),SLOT(on_pushButton_clicked()));

然后错误输出略有变化，但本质仍然相同。我该如何解决这个问题？

--编辑--15.11.14-

主窗口.h：…

private:
    Ui::MainWindow *ui;
    QRadioButton *radioButton,*radioButton_2,*radioButton_3,*radioButton_4;
    QPushButton *pushButton;
    QPlainTextEdit *plainTextEdit;
};

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow),
    pushButton(new QPushButton(this)),
    plainTextEdit(new QPlainTextEdit(this))
{
    ui->setupUi(this);
    //pushButton = new QPushButton(this);
    //plainTextEdit = new QPlainTextEdit(this);
    QObject::connect(pushButton,SIGNAL(clicked()),plainTextEdit,SLOT(on_pushButton_clicked()));
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::on_pushButton_clicked()
{
    plainTextEdit->setPlainText("Some text here");
}

结果，我得到了具有以下输出的SIGSEGV：

amember "1on_pushButton_clicked()" char *
asender @0x2 QObject
asignal "2clicked()" char *
atype Qt::AutoConnection(0) Qt::ConnectionType
this @0x7fffffffe640 QObject

它还指向qobject.h中的以下行：

339 { return connect(asender, asignal, this, amember, atype); }
349 T qFindChild(const QObject *o, const QString &name = QString());
350 QList<T> qFindChildren(const QObject *oobj, const QString &name = QString());
351 QList<T> qFindChildren(const QObject *o, const QRegExp &re);