如何修复 python 中超出范围的列表索引

Question

i have a function that append item to a list then i want to print the each using .format()

If i try to print the self.checked[0] it will print the selected item but if it try self.checked[0],self.checked[1] system crash.

the problem is when i am trying to print each item the system display this error:

 self.display_event_mouhafaza.setText(" {} over {}".format(self.checked[0],self.checked[1]))
IndexError: list index out of range

where is the error in my code?

def selectionChanged(self):
        checked = []
        for row in range(self.header_list.count()):
            item = self.header_list.item(row)
            if item.checkState():
                checked.append(item)
        print("Checked items: ", ", ".join(i.text() for i in checked))
        self.checked = [i.text() for i in checked]
        self.display_event_person.setText("total of {} ".format(self.checked[0]))
        self.display_event_mouhafaza.setText(" {} over {}".format(self.checked[0],self.checked[1]))

#part that display items in the qlistWidget
        self.header_list.clear()
        savelist = list(self.df)
        for item in savelist:
            qitem = QtWidgets.QListWidgetItem ( ) 
            qitem.setText ( item ) 
            qitem.setCheckState ( QtCore.Qt.Unchecked ) 
            self.header_list.addItem ( qitem )

here the self.checked includes 3 items.

Answer 1

self.display_event_mouhafaza.setText(" {} over {}".format(self.checked[0],self.checked[1]))

To get rid of index out of range, you would need a default value, let print empty space "" if index out of range

if len(self.checked) < 2 :
    print( 'This is your self.checked does not have second value ', self.checked)
else:
    self.display_event_mouhafaza.setText(" {} over {}".format(
             self.checked[0]
             self.checked[1]
    ))