使用Qt Designer设计水平布局，加addStretch()不起作用，解决办法？

解决办法：
将main函数中的MainWindow.show()改为：ui.show()

if __name__=='__main__':app = QApplication(sys.argv)MainWindow = QMainWindow()ui = Ui_MainWindow()ui.setupUi(MainWindow)ui.show()app.exec()

完整代码：

import  sysfrom PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QWidget, QHBoxLayout, QPushButton,QMainWindowclass Ui_MainWindow(QWidget):def __init__(self):super().__init__()self.setupUi(MainWindow)def setupUi(self,MainWindow):MainWindow.setObjectName("MainWindow")MainWindow.resize(800, 600)self.centralwidget = QtWidgets.QWidget(MainWindow)self.centralwidget.setObjectName("centralwidget")self.horizontalLayoutWidget = QtWidgets.QWidget(self.centralwidget)self.horizontalLayoutWidget.setGeometry(QtCore.QRect(290, 160, 320, 80))self.horizontalLayoutWidget.setObjectName("horizontalLayoutWidget")self.horizontalLayout = QtWidgets.QHBoxLayout(self.horizontalLayoutWidget)self.horizontalLayout.setContentsMargins(0, 0, 0, 0)self.horizontalLayout.setObjectName("horizontalLayout")self.pushButton = QtWidgets.QPushButton(self.horizontalLayoutWidget)self.horizontalLayout.addStretch(1)self.pushButton.setObjectName("pushButton")self.horizontalLayout.addWidget(self.pushButton)self.pushButton_2 = QtWidgets.QPushButton(self.horizontalLayoutWidget)self.pushButton_2.setObjectName("pushButton_2")self.horizontalLayout.addStretch(2)self.horizontalLayout.addWidget(self.pushButton_2)self.pushButton_3 = QtWidgets.QPushButton(self.horizontalLayoutWidget)self.pushButton_3.setObjectName("pushButton_3")self.horizontalLayout.addStretch(1)self.horizontalLayout.addWidget(self.pushButton_3)self.pushButton_4 = QtWidgets.QPushButton(self.horizontalLayoutWidget)self.pushButton_4.setObjectName("pushButton_4")self.horizontalLayout.addStretch(1)self.horizontalLayout.addWidget(self.pushButton_4)MainWindow.setCentralWidget(self.centralwidget)self.menubar = QtWidgets.QMenuBar(MainWindow)self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 23))self.menubar.setObjectName("menubar")MainWindow.setMenuBar(self.menubar)self.statusbar = QtWidgets.QStatusBar(MainWindow)self.statusbar.setObjectName("statusbar")MainWindow.setStatusBar(self.statusbar)self.setLayout(self.horizontalLayout)self.retranslateUi(MainWindow)QtCore.QMetaObject.connectSlotsByName(MainWindow)def retranslateUi(self, MainWindow):_translate = QtCore.QCoreApplication.translateMainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))self.pushButton.setText(_translate("MainWindow", "按钮1"))self.pushButton_2.setText(_translate("MainWindow", "按钮2"))self.pushButton_3.setText(_translate("MainWindow", "按钮3"))self.pushButton_4.setText(_translate("MainWindow", "按钮4"))if __name__=='__main__':app = QApplication(sys.argv)MainWindow = QMainWindow()ui = Ui_MainWindow()ui.setupUi(MainWindow)ui.show()app.exec()