import sys
from PySide6.QtWidgets import QApplication, QWidget
from demo3 import Ui_Form

class Window(Ui_Form,QWidget):
    def __init__(self):
        super().__init__()
        self.setupUi(self)
        self.pushButton.clicked.connect(self.change_label)

    def change_label(self):
        str1="问渠那得清如许，唯有源头活水来。"
        self.label.setText(str1)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    win = Window()
    win.show()
    sys.exit(app.exec())