Using a method from one .cs file class in another

问题:

I have 2 .cs files each with a class in it. How do I call a method in a class from Form1.cs in another class inside of Form2.cs?

Looks something like this...

Form1.cs

public partial class Class1 : ClassContainer
{
    public void awesomeMethod()
        {
        }
}

Form2.cs

class Class2 : SomethingChanged
{
    public void decentMethod()
    {
    }
}

I would like to call awesomeMethod() inside of the decentMethod(). Thanks.

回答1:

You mean, like this?

public void decentMethod()
{
    Class1 instance = new Class1();
    instance.awesomeMethod();
}

You need an instance of the class you want to call the method on.

---

Or, if you don't need/want to work with an instance, make it the method static:

public partial class Class1 : ClassContainer
{
    public static void awesomeMethod()
    {
    }
}

...

public void decentMethod()
{
    Class1.awesomeMethod();
}

回答2:

In order to call an instance method of a class, you need an instance of a class. Thus, to call Class1's awesomeMethod, you must create an instance of Class1:

Class1 c = new Class1();
c.awesomeMethod();

From your opening paragraph, though, it sounds like the two actual classes are two different forms. In that case, it doesn't really make sense for one form to create a new instance of another form purely to get at what is presumably a helper method - creating that second form is potentially an awful lot of overhead. You'd be better off putting helper methods into a separate, more lightweight class.

回答3:

I'm guessing that these aren't real method signatures.

Does awesomeMethod need any references to any of the members of decentMethod?

If not, it would be as simple as:

new Class1().awesomeMethod();

回答4:

Here is something you can try in Visual Studio. Write your use of the method without the definition. For example, somewhere in your code, type:

cls_a instance_a;

Then you get a squiggly line under cls_a. Right click "cls_a" and select generate from the popup menu. Then see what happens.

I saw App_Code directory created, and the class cls_a was generated in a file cls_a.cs in that directory. Visual Studio generated the definition. And it compiles.

You can then type the use of a method without the definition from cls_a like this:

instance_a.meth_x();

Again, right-click on the squiggly line and select generate. Let Visual Studio generate the definition for you.

I think ASP .NET requires you to put your additional classes in the App_Code subdirectory. And if you need to bend ASP.NET to your way, I think the Web.config file can be edited so you can put your code files wherever you want. I have not reviewed how to do this so I leave that to you or someone else.

Anyway, not having your classes and methods in App_Code subdirectory can cause your classes and functions to not be seen in your web form code, even though everything else is correct.

回答5:

Ok i am a beginner at this and wondered the same thing. I believe I understand what you're asking. I just tried this and after a few attempts it clicked, and being newer to this maybe I can simplify it with my words. I don't know which program you are using but I used Visual Studio 2016. I created two forms(Form1 and Form2) each containing a button. Form1 button and Form2 button. When I click Form1 button it calls a method from form2, and when I click Form2 button it calls a method from Form1. I noticed that in the solution explorer it shows both forms, and everything they contain. I've done a lot of research and correct me if I am wrong but I believe the order goes like this from parent container to child( Namespace>Class>Method ). Believing this to be true I figured that I would need to call the class before I could call the method.

These are my scripts.

Form1 :

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

    }

    private void Form1_Load(object sender, EventArgs e)
    {
        Form2 frm2 = new Form2();
        frm2.Show();
    }

    private void f1button_Click(object sender, EventArgs e)
    {
        f2Words f2w = new f2Words();
        f2w.Words2();

    }
}
public class f1Words
{
    public void Words1()
    {
        MessageBox.Show("Form 1 Method Calling Worked!");
    }
}

---

Form2:

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }

    private void Form2_Load(object sender, EventArgs e)
    {

    }

    private void f2button_Click(object sender, EventArgs e)
    {
        f1Words f1w = new f1Words();
        f1w.Words1();

    }
}
public class f2Words
{
    public void Words2()
    {
        MessageBox.Show("Form 2 Method Calling Worked!");
    }
}

In the Solution Explorer window it shows the classes of both Form1 and Form2. So I decided to try to call new instances of these classes.

"f1Words f1w = new f1words()" and "f2Words f2w = new f2Words()".

Then right after this I called those new instances of the classes into play with the methods they contained.

"f1w.Words1()" and "f2w.Words2()"

The end result was a success. When I click Form1's Button1 it called Form2's F2Words Class and pulled the Words2 Method out of it opening a message box saying "Form2 Method Calling Worked!", and visa versa for the Form2 Button2.

As this post is 4 years old I assume you've already found this out on your own and perhaps found a better solution, but for anyone else asking this same question in the future I hope this helps you out.

回答6:

Assume the main Form is frmMain. Make a static declaration outside frmMain()'s constructor; assign it inside that same constructor:

public static frmMain p_frmMain = null;
public frmMain()
{
    InitializeComponent();
    :
    p_frmMain = this;
}

From another class (using main's namespace in that same solution), call, say, main's 'btnHelloWorld_Click()' method:

AnotherClass_EventHandler(object sender, EventArgs e)
{
:  // Call frmmain()'s 'btnHelloWorld_Click' event:
   frmMain.p_frmMain.btnHelloWorld_Click (sender, e);
:
}
// Quick, dirty and done.