为什么Application.Exit提示我两次？

Question

当我按下表单上的X时,如何阻止消息框显示两次？仅供参考,但是按钮点击工作正常,这是提示我两次的X.

   private void xGameForm_FormClosing(object sender, FormClosingEventArgs e)
   {
       //Yes or no message box to exit the application
       DialogResult Response;
       Response = MessageBox.Show("Are you sure you want to Exit?", "Exit", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
       if (Response == DialogResult.Yes)
           Application.Exit();

   }
   public void button1_Click(object sender, EventArgs e)
   {
       Application.Exit();
   }

Answer 1

在您进行Application.Exit调用时,表单仍处于打开状态(结束事件甚至尚未完成处理).Exit调用导致表单关闭.由于表单尚未关闭,因此它再次通过Closing路径并命中您的事件处理程序.

解决此问题的一种方法是记住实例变量中的决策

private bool m_isExiting;

   private void xGameForm_FormClosing(object sender, FormClosingEventArgs e)
   {
       if ( !m_isExiting ) {
         //Yes or no message box to exit the application
         DialogResult Response;
         Response = MessageBox.Show("Are you sure you want to Exit?", "Exit",   MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
         if (Response == DialogResult.Yes) {
           m_isExiting = true;
           Application.Exit();
         }
   }
   public void button1_Click(object sender, EventArgs e)
   {
       Application.Exit();
   }