如何从一种形式到另一种形式获得相同的价值两种不同的形式 [英] How to get same value from one form to another two difrent forms

问题描述

我有2个表格 novkontakt 和 novkontakt1 谁应该从 tipNaLice 表格获得相同的价值，

一个表单kontakt工作完美，但是当添加secound有错误时

I have 2 forms novkontakt and novkontakt1 who should get same value from tipNaLice form,
when is one form kontakt work perfect, but when add secound have error

System.NullReferenceException: 'Object reference not set to an instance of an object.'

我的尝试：



这是我的代码来自tipNaLice

What I have tried:

this is my code from tipNaLice

novKontakt orForm;
novKontakt1 or1Form;

public tipNaLice(novKontakt inForm)
{
    orForm = inForm;
    InitializeComponent();
}

public tipNaLice(novKontakt1 in1Form)
{
    or1Form = in1Form;
    InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
     foreach (object redovi in listBox1.SelectedItems)
     {
        orForm.textLice = redovi.ToString();
        orForm.vmetniTipNaLice();
        or1Form.textLice1 = redovi.ToString();
        or1Form.vmetniTipNaLice1();

        this.Close();
     }

}

推荐答案

不要这样做。这意味着你的表单需要了解彼此以及它们是如何工作的 - 这很糟糕，并且使你的代码难以正确维护。



具体取决于关系 两种形式之间。

看看这些，其中一个适合你的情况。

创建另一个实例的表格：

Don't do it that way. That means that your forms need to know about each other and how they work - that's bad and makes your code hard to maintain properly.

Exactly how depends on the "relationship" between the two forms.
Have a look at these, one of them will fit your circumstances.
The form that creates an instance of another:

MyForm mf = new MyForm();
mf.Show();

是父，另一种形式是孩子。

（这并不意味着任何正式的MDI关系）



转让两种表格之间的信息，第1部分：父母与子女 [ ^ ]

在两种表格之间传递信息，第2部分：儿童到父母 [ ^ ]

在两种形式之间传递信息，第3部分：儿童到儿童 [ ^ ]

Is the "parent", the other form is the "child".
(This doesn't imply any formal MDI relationship)

Transferring information between two forms, Part 1: Parent to Child[^]
Transferring information between two forms, Part 2: Child to Parent[^]
Transferring information between two forms, Part 3: Child to Child[^]

当 novKontakt1时表单是开放做某事（在我的情况下从列表框发送值）

所以这是我的解决方案

When novKontakt1 form is open do something (in my case send value from listbox)
so this is my solution

public static Form OpenForm(Type FormType)
        {
            foreach (Form OpenForm in Application.OpenForms)
            {
                if (OpenForm.GetType() == FormType)
                    return OpenForm;
            }

            return null;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            novKontakt1 nk1 = null;
            
            foreach (object redovi in listBox1.SelectedItems)
            {
                if ((nk1 = (novKontakt1)OpenForm(typeof(novKontakt1))) == null)
                {
                    orForm.textLice = redovi.ToString();
                    orForm.vmetniTipNaLice();
                }
                else
                {
                    or1Form.textLice1 = redovi.ToString();
                    or1Form.vmetniTipNaLice1();
                }
                this.Close();
            }
        }

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