組合框了selectedValue崩潰控制框在C＃

Question

當過我是從我的組合框中我的WinForms應用程序分配選定的值不會關閉通過controlBox（最小化，最大化工作，但關閉不！）

如果我註釋掉下面的代碼它似乎工作：

private void Form1_Load(object sender, EventArgs e) 
    { 
     // TODO: This line of code loads data into the 'dataSet1.NewSelectCommand' table. You can move, or remove it, as needed. 
     this.newSelectCommandTableAdapter.Fill(this.dataSet1.NewSelectCommand); 

    } 

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) 
    { 
     string databaseName = string.Empty; 
     databaseName = comboBox1.SelectedItem.ToString(); 
    } 

Answer 1

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    string databaseName = string.Empty; 
    if(comboBox1.SelectedItem != null) databaseName = comboBox1.SelectedItem.ToString(); 
}