Placing values into a dictionary and show them in textboxes

Question

I hope this is not a silly question but I'm trying to create a simple form which has 2 numeric updowns with a button I take the values and store them in a dictionary as two strings. Now I think this goes fine but I want to show the values after pressing the button also in separated textboxes.

namespace TestWayPointEditor
{
    public struct Coordinate
    {
    public string Latitude { get; set; }
    public string Longitude { get; set; }

    public Coordinate(string latitude, string longitude)
    {
    this.Latitude = latitude;
    this.Longitude = longitude;
    }

}
public partial class Form1 : Form
    {

    HashSet<Coordinate> WayPoints = new HashSet<Coordinate>();
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void btnAdd_Click(object sender, EventArgs e)
    {
        //Set lat and lon values in a string
        string Lat = LatUpDown.Value.ToString();
        string Lon = LongUpDown.Value.ToString();

        WayPoints.Add(new Coordinate(Lat, Lon));

    }
}
}

My form looks like this to give an idea of what I am doing

So if I have a latitude and longitude and press add it should appear in the textboxes and save it on the background. If I change the values and press add the second row should be filled and this should go on and on. Besides of that I want when I close this form (it is a second form of project) and open it again I did not loose my values.

I gues I have to make a class for this and it should be public. But I actually dont know where to start. I hope someone could guide.

Answer 1

The Dictionary is better for data with key-value structure when we might need to get the value using the key...

Obviously latitude isn't a key for longitude therefore the Dictionary collection isn't the best choice here unless the key would contain something meaningful.

We could create a custom struct Coordinate to store our values. An example of structure like this is System.Drawing.Point.

public struct Coordinate
{
    public string Latitude  { get; } 
    public string Longitude { get; }

    public Coordinate(string latitude, string longitude)
    {
        this.Latitude = latitude;
        this.Longitude = longitude;
    }
}

As we don't want our collection to allow adding the same value twice the List<T> isn't the best choice either.

We can benefit from using the HashSet<T> which has high-performance set operations and contains no duplicate elements:

HashSet<Coordinate> WayPoints = new HashSet<Coordinate>();

public Form1()
{
    InitializeComponent();
}

...

WayPoints.Add(new Coordinate(.. , ..));

Now if we need WayPoints to exist even after the form is closed we have to move it outside of the Form into some other object.

If WayPoints collection should have values after we restart the app - a use of persistent storage is required and we could serialize and save our values into database or into file.

An example of a very simple static storage:

public static class DataStorage
{
    public static HashSet<Coordinate> WayPoints { get; }

    static DataStorage()
    {
        WayPoints = new HashSet<Coordinate>();
    }

    public static Coordinate? TryGetCoordinate(string latitude, string longitude)
    {
        var coordinate = new Coordinate(latitude, longitude);
        return WayPoints.Contains(coordinate) ? (Coordinate?)coordinate : null;
    } 
}

P.S.

We could loop through all WayPoints using foreach and assign each coordinate to some Textbox.Text.

In case when we need to get certain Coordinate from WayPoints all we need to do is to create a new instance of Coordinate and check if it exists in WayPoints collection. We've implemented it in the method TryGetCoordinate.

Use it like so:

Coordinate? foundInStorage = DataStorage.TryGetCoordinate("123.5", "300");
if(foundInStorage != null)
{
    // something with foundInStorage.Value
}