从队列中获取消息时更新标签

Question

我正在尝试更新标签以显示当它通过队列接收到数字时正在倒计时的数字。我可以看到它正在控制台中打印，但标签没有改变。任何帮助或建议都会有所帮助！

这是我的代码：

import tkinter as tk
import time
import threading
import queue

class GUIApp:
    def __init__(self):
        self.root = tk.Tk()
        self.buttonCountDown = tk.Button(text='Count Down', command=self.countDownAction)
        self.buttonCountDown.pack()
        self.label = tk.Label(text='default')
        self.label.pack()
        self.queue = queue.Queue()
        self.root.mainloop()

    def countDown(self, seconds):
        for i in range(seconds, 0, -1):
            self.queue.put(i)
            time.sleep(1)

    def listenToQueue(self):
        while True:
            try:
                if self.queue.empty() == False:
                    print(self.queue.get(0))
                    self.label['text'] = self.queue.get(0)
                elif self.queue.empty() == True:
                    pass
            except queue.Empty:
                pass

    def countDownAction(self):
        listenThread = threading.Thread(target=self.listenToQueue)
        listenThread.start()
        thread = threading.Thread(target=self.countDown, args=(5,))
        thread.start()
        thread.join()

app = GUIApp()

Answer 1

您需要知道的第一件事是Queue.get() 删除项目并将其返回，类似于dict.pop()。因此，当您执行print(self.queue.get(0)) 时，该项目已从队列中删除。如果你想打印和配置它，你必须先将它分配给一个变量：

def listenToQueue(self):
    while True:
        try:
            if self.queue.empty() == False:
                s = self.queue.get(0)
                print (s)
                self.label['text'] = s
            elif self.queue.empty() == True:
                pass
        except queue.Empty:
            pass

接下来，调用thread.join() 将等待线程终止。在当前设置中，您根本不需要调用此方法。

def countDownAction(self):
    listenThread = threading.Thread(target=self.listenToQueue)
    listenThread.start()
    thread = threading.Thread(target=self.countDown, args=(5,))
    thread.start()
    #thread.join() #not required