How to consume List from another class-CodePudding

Whenever I give new when instantiating a class or list, will it be recreated? I'm having trouble consuming a list that I fed into another class. I'll give an example of my question to make it clearer:

I have the Customers class:


public class Clients
{
    public int id { get; set; }
    public string name { get; set; } 
}

and I have another class called:

public class CustomerList
{
    public List<Customers> dataCustomers;
}

these two are inside the same file or better same namespace.

Now I will feed this list through another Form1, so first I will instantiate it in this new form1:

CustomerList listCustomers = new CustomerList();

Now I'm going to feed the data into the class:

Customers customer = new Customers()
{
     id = 1,
     name = "Matthew"
}

and finally I will add the records inside the list:

listCustomer.dataCustomers.Add(customer);

Now I want to consume this list from another form/class, but I don't know how to do it. I tried instantiating it again in this new class. but it always returns saying that dataClientes was null, saying that the object is not being referenced. so well I couldn't understand this concept well, how to consume a list that I fed into another form/class.

In this form that I want to consume, I did it like this, I instantiated it:

CustomerList objCliente = new CustomerList();

and to test, I tried to play inside a message box, just to see the result.

MessageBox.Show(objCliente.dataCliente.ToString());

CodePudding user response：

To access the list of customers in the second form, you will need to pass a reference to the listCustomers object to the second form. You can do this by creating a constructor for the second form that accepts a CustomerList object as an argument, and then storing that object in a field of the second form. like that:

public class Form2
{
    private CustomerList listCustomers;

    public Form2(CustomerList listCustomers)
    {
        this.listCustomers = listCustomers;
    }
}

Then when you create an instance of "Form2" in your first form, you can pass a reference to the "listCustomers" object as an argument to the constructor:

Form2 form2 = new Form2(listCustomers);

You can then access the list of customers by calling the dataCustomers property on the listCustomers object.

CodePudding user response：

Make your property to be static, so that it can be accessed anywhere.

public class CustomerList
{
    static public List<Customers> dataCustomers;
}

The way to add new customer now become like this :

CustomerList.dataCustomers.Add(customer);

and to access it also same. You can access it using this way :

CustomerList.dataCustomers