Why Does My WPF App Throw a 'The calling thread cannot access this object' Exception When Accessing UI Elements?

WPF application throws out the cause of "calling threads cannot access this object" abnormal cause

The abnormal information appearing in the code is "The call cannot access this object, because another thread owns it". This error occurred when trying to access UI elements from non -embarrassing threads.

WPF framework restricts access to UI elements, and only the threads of creation can be accessed. This ensures the response ability of UI and prevent thread problems. In this example, the problem with problems is

.

txtSearchCountry.Text Background work thread and UI thread

Code seems to use background work threads to perform asynchronous operations, such as data retrieval. The background working threads run on different threads from the main UI thread. When visiting the UI element from the background workline, a certain mechanism must be used to ensure the security of the thread.

Dispatcher and cross -threaded call

To access the UI element safely from other threads, you need to use the class. provides a way to queue up to UI threads.

Code correction Dispatcher Dispatcher

In order to solve the exception, the method can be modified. The method is as follows:

By using , you can ensure that the code of

is executed on the main UI thread to avoid ownership. In addition, the empty value check was simplified in the code, and

instead of GetGridData. Finally, use

to specify the Dispatcher object to be used to avoid potential ambiguity.

<code class="language-csharp">private void GetGridData(object sender, int pageIndex)
{
    Standards.UDMCountryStandards objUDMCountryStandards = new Standards.UDMCountryStandards();
    objUDMCountryStandards.Operation = "SELECT";

    this.Dispatcher.Invoke(() => // 使用 this.Dispatcher 确保在正确的 Dispatcher 上调用
    {
        // 访问UI元素 (txtSearchCountry)
        objUDMCountryStandards.Country = string.IsNullOrWhiteSpace(txtSearchCountry.Text) ? null : txtSearchCountry.Text.Trim(); // 使用更简洁的空值检查
    });

    DataSet dsCountryStandards = objStandardsBusinessLayer.GetCountryStandards(objUDMCountryStandards);
    // ... 方法的其余部分保持不变
}</code>

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