How to solve this problem with configuring the ComboBox component?

Question

This code does not set the correct value in the combo box. This is due to the fact that they are from different contexts.

Also, in my actual problem , neither overload == nor overriding Equals () in MyClass also works.

Any alternative way?

How to solve this problem?

Myclass.cs

public class MyClass
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public MyClass(int id, string name)
        {
            ID = id;
            Name = name;
        }

        public static List<MyClass> Get()
        {
            return new List<MyClass>
            {
                new MyClass(2, "AAA"),
                new MyClass(4, "BBB"),
                new MyClass(5, "CCC"),
                new MyClass(7, "DDD"),
                new MyClass(10, "EEE")
            };
        }
    }

ComboBoxForm.cs

public partial class ComboBoxForm : Form
    {
        public ComboBoxForm()
        {
            InitializeComponent();
        }

        private void Form1_Shown(object sender, EventArgs e)
        {
            LoadDataToComboBoxFromDatabase();
        }

        private void LoadDataToComboBoxFromDatabase()
        {
            comboBox1.Items.Clear();

            List<MyClass> list = MyClass.Get();

            foreach(MyClass mc in list)
            {
                comboBox1.Items.Add(mc);
            }

            comboBox1.DisplayMember = "Name";
            comboBox1.ValueMember = "ID";

            comboBox1.SelectedIndex = 0;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int ID = 5;//This is what I have.
            comboBox1.SelectedItem = .............how?
        }
    }

Answer 1

I believe your Equals comparison may be wrong. For NHibernate, I use the following method Equals():

public static class EntityUtil
{
    public static bool Equals(IEntity a, IEntity b)
    {
        // Transient entitys are never equal (unless they are ReferenceEquals)!

        return
            ReferenceEquals(a, b) || (
                !((object)a == null || (object)b == null) &&
                !(IsTransient(a) || IsTransient(b)) &&
                NHibernateProxyHelper.GetClassWithoutInitializingProxy(a) == NHibernateProxyHelper.GetClassWithoutInitializingProxy(b) &&
                a.Id.Equals(b.Id)
            );
    }

    public static bool IsTransient(IEntity entity)
    {
        return entity.Id == 0;
    }
}

I defined this method in a separate helper class and use it in my entity:

public class Entity : IEquatable<Entity>, IEquatable<IEntity>
{
    private int? _hashCode;

    public virtual int Id { get; protected set; }

    public override bool Equals(object obj)
    {
        return EntityUtil.Equals((IEntity)this, obj as IEntity);
    }

    public virtual bool Equals(Entity obj)
    {
        return EntityUtil.Equals((IEntity)this, (IEntity)obj);
    }

    public virtual bool Equals(IEntity obj)
    {
        return EntityUtil.Equals((IEntity)this, obj);
    }

    public static bool operator ==(Entity a, Entity b)
    {
        return EntityUtil.Equals((IEntity)a, (IEntity)b);
    }

    public static bool operator !=(Entity a, Entity b)
    {
        return !(a == b);
    }

    public override int GetHashCode()
    {
        // GetHashCode needs to return a stable value.

        if (!_hashCode.HasValue)
        {
            _hashCode =
                NHibernateProxyHelper.GetClassWithoutInitializingProxy(this).GetHashCode() ^
                ((IEntity)this).Id.GetHashCode();
        }

        return _hashCode.Value;
    }
}

NHibernate. , .