Click item in listbox and View details in multiline textbox

问题

I would like to click on an item in a listbox and display the attributes that were passed into that listbox to a multiline textbox.

Below is the code I have written on form initialisation

public Form1()
    {
        InitializeComponent();
        ReadFromFile.Read("sample.GED");

        foreach (KeyValuePair<int, Individual> kvp in ReadFromFile.individuals)
        {
            listBox2.Items.Add("ID = " + kvp.Value.id + " Name = " + kvp.Value.name.givenName + " " + kvp.Value.name.surname + " DoB = " + kvp.Value.birth.date);
        }

        int testIndividual = 94;

        string genderOut = "";
        if (ReadFromFile.individuals[testIndividual].gender == "M")
        {
            genderOut = "MALE";
        }
        else if (ReadFromFile.individuals[testIndividual].gender == "F")
        {
            genderOut = "FEMALE";
        }

        try
        {
            textBox1.AppendText(
                "Name = " + ReadFromFile.individuals[testIndividual].name.givenName + " "
                + ReadFromFile.individuals[testIndividual].name.surname
                + Environment.NewLine + "Gender = " + genderOut
                + Environment.NewLine + "Birth date = " + ReadFromFile.individuals[testIndividual].birth.date
                + Environment.NewLine + "Birth place = " + ReadFromFile.individuals[testIndividual].birth.place
                + Environment.NewLine + "Death date = " + ReadFromFile.individuals[testIndividual].death.date
                + Environment.NewLine + "Death place = " + ReadFromFile.individuals[testIndividual].death.place);
        }
        catch
        {
            MessageBox.Show("This individual doesnt exist");
        }
    }
}

I would like to add more so I can click on a listbox item and the details for that item will be shown in the textbox

I get the feeling I may have to override the ToString() method or regex it. Im still quite a novice programmer so go easy on me :) THANK YOU

回答1:

You need to handle the SelectedIndexChanged event for your listbox.

One way to do this is to bring up Form1.cs[Design] and select the listbox. In the property grid (Alt+Enter) click the icon that looks like this:

Find the event SelectedIndexChanged and double click it. That will hook up an event handler for you in the auto generated Form1.cs.designer file.

Next, replace the code for your Form1 class with the following:

public partial class Form1 : Form
{
    private Dictionary<int, Individual> _individuals;

    public Form1()
    {
        InitializeComponent();
        ReadFromFile.Read("sample.GED");
        _individuals = ReadFromFile.individuals;

        listBox1.DataSource = _individuals.Select(individual => individual.Value).ToList();
        listBox1.DisplayMember = "name";
        listBox1.ValueMember = "id";  
    }

    private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
    {
        textBox1.Clear();
        var individual = listBox1.SelectedItem as Individual;
        string genderOut = (individual.Gender == "M") ? "MALE" : "FEMALE";
        var displayText 
            = String.Format("Name = {0} {1}\r\n" +
                            "Gender = {2}\r\n" +
                            "Birth date = {3}\r\n" +
                            "Birth place = {4}\r\n" +
                            "Death date = {5}\r\n" +
                            "Death place = {6}"
                            , individual.name.givenName
                            , individual.name.surname
                            , genderOut
                            , individual.birth.date
                            , individual.birth.place
                            , individual.death.date
                            , individual.death.place);
        textBox1.AppendText(displayText);
    }
}

A few notes about some of the things i've changed.

I've moved the code that was setting the textbox value into the SelectedIndexChanged event handler
I've refactored that code so that it's more readable by using the static String.Format method (all those Environment.NewLine repeats you had were messy).
I've setup the data for the list box using the DataSource property instead of your foreach loop.

Also, one thing you'll notice with this is that the list items in the listbox will not show the correct text. This is because you appear to be using some custom classes or structs for the name, birth and death of an Individual? To fix this, you need to add a new property to the Individual class like this:

public class Individual
{
    // ... your code
    public string DisplayName
    {
        get { return String.Format("{0} {1}), name.givenName, name.surname; }
    }
    // ... the rest of your code
}

Then you will need to change the line in my code above that looks like this:

listBox1.DisplayMember = "name";

to this:

listBox1.DisplayMember = "DisplayName";

Final note: You should probably be using "Upper Camel Case" for your property names. That means that they start with an upper case letter and then the first letter of each word is also upper case. For example, name.givenName should be Name.GivenName. This is a widely used convention.

来源：https://stackoverflow.com/questions/9856780/click-item-in-listbox-and-view-details-in-multiline-textbox

标签

textbox

listbox