如何在列表框 py3 中设置默认光标选择

Question

这是我的代码，它工作正常 当程序启动时，列表框中没有选择，我想在列表框中设置默认选择，以防用户未进行选择。 请帮忙！

### frame_3 widgets.
frame_3 = Frame(frame_2)
label_1a = Label(frame_3, relief = 'solid', width = 17)
label_1a.configure(text = "Start of Period month")
### listbow_1 and static attributes.
listbox_1 = Listbox(frame_3, exportselection=0, width = 12, height = 12)
for item in ['January','Febuary','March',
'April','May','June',
'July','August','September',
'October','November','December']:
listbox_1.insert(END,item)
label_2a = Label(frame_3, relief = 'groove', width = 10)
label_2a.configure(text = "Start day")
entry_1 = Entry(frame_3, width = 2)
### geometry frame_3
label_1a.grid (column = 0, row = 2)
frame_3.grid  (column = 0, row = 2)
listbox_1.grid(column = 0, row = 3)
label_2a.grid (column = 0, row = 5)
entry_1.grid  (column = 1, row = 5)

Answer 1

您可以使用listbox.selection_set(0)选择列表中的第一项

文档中的更多内容： Listbox.selection_set

完整示例

import tkinter as tk
def test():
# here you can get selected element
print('previous:', listbox.get('active'))
print(' current:', listbox.get(listbox.curselection()))
# --- main ---
root = tk.Tk()
listbox = tk.Listbox(root)
listbox.pack()
listbox.insert(1, 'Hello 1')
listbox.insert(2, 'Hello 2')
listbox.insert(3, 'Hello 3')
listbox.insert(4, 'Hello 4')
listbox.selection_set(0)
button = tk.Button(root, text="Test", command=test)
button.pack()