如何使用PushButton关闭Qdialog窗口？

Question

我目前正在从事这个GUI项目。我创建了一个设置窗口，但是在按下按钮后我无法将其关闭。我尝试使用self.close（），self.accept（），self.reject（）方法。当我单击按钮时，什么都不会发生。这是我的代码，它简化了：

from PyQt5.QtWidgets import (QLineEdit, QWidget, QMenu, QMenuBar, QAction, 
                            QMainWindow, QApplication, QDialog, QPushButton, QVBoxLayout)
from PyQt5.QtCore import QSize, QRect, QMetaObject, QCoreApplication, QObject, Qt


class Ui_Dialog(QDialog):
    def __init__(self):
        super(Ui_Dialog, self).__init__()


    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(100, 100)
        self.verticalLayout= QVBoxLayout(Dialog)

        self.lineEdit = QLineEdit(Dialog)
        self.lineEdit.setObjectName("lineEdit")        
        self.verticalLayout.addWidget(self.lineEdit)
        self.pushButton = QPushButton(Dialog)
        self.pushButton.setObjectName("pushButton")
        self.verticalLayout.addWidget(self.pushButton)
        self.pushButton_2 = QPushButton(Dialog)
        self.pushButton_2.setObjectName("pushButton_2")
        self.verticalLayout.addWidget(self.pushButton_2)


        self.pushButton.clicked.connect(self.close)
        self.pushButton_2.clicked.connect(self.save)
    

        self.retranslateUi(Dialog)
        QMetaObject.connectSlotsByName(Dialog)



    def save(self):
        global setting
        setting = self.lineEdit.text()
        self.done(1)
        self.accept()
        self.deleteLater()
        self.destroy()
        self.reject()
        self.close()



    def retranslateUi(self, Dialog):
        _translate = QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Settings"))
        self.pushButton_2.setText(_translate("Dialog", "Save"))
        self.pushButton.setText(_translate("Dialog", "Cancel"))



class Ui_MainWindow(QObject):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(1250, 609)
        MainWindow.setMinimumSize(QSize(833, 600))
        self.centralWidget = QWidget(MainWindow)
        MainWindow.setCentralWidget(self.centralWidget)
        self.centralWidget.setObjectName("centralwidget")

        self.menubar = QMenuBar(MainWindow)
        self.menubar.setGeometry(QRect(0, 0, 906, 21))
        self.menubar.setObjectName("menubar")
        self.menuOptions = QMenu(self.menubar)
        self.menuOptions.setObjectName("menuOptions")
        MainWindow.setMenuBar(self.menubar)
        self.actionSettings = QAction(MainWindow)       
        self.actionSettings.setObjectName("actionSettings")
        self.menuOptions.addAction(self.actionSettings)
        self.menubar.addAction(self.menuOptions.menuAction())

        self.actionSettings.triggered.connect(self.preferences)
       

        self.retranslateUi(MainWindow)
        QMetaObject.connectSlotsByName(MainWindow)



    def retranslateUi(self, MainWindow):
        _translate = QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "closinDialogSample"))
        self.menuOptions.setTitle(_translate("MainWindow", "Options"))
        self.actionSettings.setText(_translate("MainWindow", "Settings"))


    def preferences(self):
        self.preferences_dialog = QDialog()
        self.preferences_dialog.ui = Ui_Dialog()
        self.preferences_dialog.ui.setupUi(self.preferences_dialog)
        self.preferences_dialog.setAttribute(Qt.WA_DeleteOnClose)
        self.preferences_dialog.setModal(True)
        self.preferences_dialog.show()


if __name__ == "__main__":
    import sys
    app = QApplication(sys.argv)
    MainWindow = QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

谢谢您的阅读。