Xamarin.Android SQLite.NET

Question

我想创建一个显示数据库记录的应用程序，我可以添加新记录。我第一次在C＃中使用数据库，所以我在这个主题中完全不喜欢。当我点击按钮接受时，比编译器显示“发生未处理的异常。”。我不知道我做错了什么。 我的代码：

public class Person
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Address { get; set; }
    public string CellPhoneNumber { get; set; }
    public string EMailAddress { get; set; }

    public Person() { }

    public Person(string firstName, string lastName, string address, string cellPhoneNumber, string eMailAddress)
    {
        FirstName = firstName;
        LastName = lastName;
        Address = address;
        CellPhoneNumber = cellPhoneNumber;
        EMailAddress = eMailAddress;
    }
}

public class PersonDatabase
{
    public SQLiteConnection connection;

    static string baseName = "Person.db";
    static string basePath = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
    static string path = Path.Combine(basePath, baseName);

    public PersonDatabase()
    {
        // If database don't exist then, will created new file. Else open exist file.
        if (!File.Exists(path))
        {
            connection = new SQLiteConnection(path);
            connection.CreateTable<Person>();
        }
        connection = new SQLiteConnection(path);
    }

    public PersonDatabase(Person person) : base()
    {
        //person.Id = connection.Table<Person>().Count() + 1;

        connection.Insert(person);
        connection.Update(person);
    }
}

public class MainActivity : Activity
{
    public PersonDatabase database = new PersonDatabase();
    private List<Person> personList = new List<Person>();

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        var addButton = FindViewById<Button>(Resource.Id.addButton);

        var query = database.connection.Table<Person>();

        foreach (var person in query)
        {
            personList.Add(person);
        }

        var listView = FindViewById<ListView>(Resource.Id.listView);
        listView.Adapter = new ListViewAdapter(this, personList);

        addButton.Click += (object sender, EventArgs e) =>
        {
            StartActivity(typeof(FormActivity));
        };
    }
}

 [Activity(Label = "FormActivity")]
public class FormActivity : Activity
{
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Form);

        var firstName = FindViewById<EditText>(Resource.Id.editTextFirstName);
        var lastName = FindViewById<EditText>(Resource.Id.editTextLastName);
        var address = FindViewById<EditText>(Resource.Id.editTextAddress);
        var cellPhoneNumber = FindViewById<EditText>(Resource.Id.editTextCellNumber);
        var eMailAddress = FindViewById<EditText>(Resource.Id.editTextMail);

        var acceptButton = FindViewById<Button>(Resource.Id.acceptButton);

        acceptButton.Click += (object sender, EventArgs e) =>
        {
            Person newPerson = new Person(firstName.Text, lastName.Text, address.Text, cellPhoneNumber.Text, eMailAddress.Text);

            var personDatabase = new PersonDatabase(newPerson);                

            StartActivity(typeof(MainActivity));
            Finish();
        };
    }
}