多线程如何访问界面上的某一个控件，并返回控件的值！

Question

如题：例如我要获得ComboBox里的值。下面是代码
        private delegate string GetVersion(); 
        private string GetDataVersion()
        {
            string version ="";
            if (this.comboBoxDataVersion.InvokeRequired)  // 如果没有选择
            {
                GetVersion getversion = new GetVersion(GetDataVersion);
                this.comboBoxDataVersion.Invoke(getversion, new object[] {});                //return version;
            }
            else
            {
                if (this.comboBoxDataVersion.SelectedItem == null)
                {
                    return version;
                }
                Item selectedItem = this.comboBoxDataVersion.SelectedItem as Item;
                version = selectedItem.value.ToString();
                //return version;
            }
            return version;
        }
多线程中调用：            string version = GetDataVersion();
            if (version == "")
            {
                MessageBox.Show("请选择作者");
                return;
            }

Answer 1

private delegate void GetVersion(); 
        private string GetDataVersion()
        {
            string version ="";
            if (this.comboBoxDataVersion.InvokeRequired)  // 如果没有选择
            {
                GetVersion getversion = new GetVersion(delegate() {version =selectedItem.value.ToString(); });
                this.comboBoxDataVersion.Invoke(getversion, new object[] {});                //return version;
            }
            else
            {
                if (this.comboBoxDataVersion.SelectedItem == null)
                {
                    return version;
                }
                Item selectedItem = this.comboBoxDataVersion.SelectedItem as Item;
                version = selectedItem.value.ToString();
                //return version;
            }
            return version;
        }

Answer 2

楼上的，好像行。错误 1 “string DMSClient.PlanProjectTaskManage.Program.ProgramManageForm.GetDataVersion()”的返回类型错误 E:\network\DMSCLIENT\DMSClient.TaskManage\Program\ProgramManageForm.cs 119 41 DMSClient.PlanProjectTaskManage如果函数也定义成void型，那么我的返回值通过什么获得。谢谢！

Answer 3

private delegate string GetVersion(); 
        private string GetDataVersion()
        {
            string version ="";
            if (this.comboBoxDataVersion.InvokeRequired)  // 如果没有选择
            {
                GetVersion getversion = new GetVersion(GetDataVersion);
                version = this.comboBoxDataVersion.Invoke(getversion, new object[] {});//注意前面的=号                //return version;
            }
            else
            {
                if (this.comboBoxDataVersion.SelectedItem == null)
                {
                    return version;
                }
                Item selectedItem = this.comboBoxDataVersion.SelectedItem as Item;
                version = selectedItem.value.ToString();
                //return version;
            }
            return version;
        }

Answer 4

gisfarmer 说的 也存在 object 转换为 string 的问题啊？ 求答案！