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How to set SelectedItem to ComboBox?

I'm trying set a SelectedItem to a ComboBox. I have one class usuario and when I open the Form I want to usuario was setted to combobox.

How could I do this ?

trying.

//setting datasource to combobox
Usuario usuario1 = new Usuario("name", "lastname");
Usuario usuario2 = new Usuario("name", "lastname");
IList<Usuario> list = new List<Usuario>();
list.Add(usuario1);
list.Add(usuario2);
comboBox.DataSource = list;

//form is opened and display the last usuario that was selected
comboBox.SelectedItem = usuario;

If what you mean is to show the last item that was added, then you could try to use comboBox1.SelectedIndex = comboBox1.Items.Count - 1; :

//setting datasource to combobox
Usuario usuario1 = new Usuario("name", "lastname");
Usuario usuario2 = new Usuario("name", "lastname");
IList<Usuario> list = new List<Usuario>();
list.Add(usuario1);
list.Add(usuario2);
comboBox1.DataSource = list;

//form is opened and display the last usuario that was added
comboBox1.SelectedIndex = comboBox1.Items.Count - 1;

I tested using:

string usuario1 = "first";
string usuario2 = "last";
IList<string> list = new List<string>();
list.Add(usuario1);
list.Add(usuario2);
comboBox1.DataSource = list;

//form is opened and display the last usuario that was added
comboBox1.SelectedIndex = comboBox1.Items.Count - 1;

And this is the result:

在此处输入图片说明

The below works just fine. When the form loads the combo box has 3 items in total and usarioN pre selected. For the sake of better understanding I have given proper names to the instances of Usario.

Usuario usuario1 = new Usuario("name1", "lastname1");
Usuario usuario2 = new Usuario("name2", "lastname2");
Usuario usuarioN = new Usuario("nameN", "lastnameN");

IList<Usuario> list = new List<Usuario>();
list.Add(usuario1);
list.Add(usuario2);
list.Add(usuarioN);

cmbItems.DataSource = list;
//property names
cmbItems.DisplayMember = "name";
cmbItems.ValueMember = "lastname";

cmbItems.SelectedItem = usuarioN;

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