How to refresh picturebox with program.cs?

Question

Program.cs code:

namespace _1
    {
     static class Program
    {
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    /// 
    public static Form2 form2;
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
        form2 = new Form2();

    }
}

Form1 Code:

Program.form2.pictureBox1.Refresh();

Error:

Object reference not set to an instance of an object.

Not sure why there's an error, I've asked google and no help. Thanks for your help.

Object reference not set to an instance of an object. error occured when you try to access without initializing/assigning any value. — Miller, Oct 12 '13 at 23:57
put form2 = new Form2() before the Application.Run(new Form1()) — Brad, Oct 13 '13 at 01:18
Almost all cases of `NullReferenceException` are the same. Please see "[What is a NullReferenceException in .NET?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-in-net)" for some hints. — John Saunders, Oct 13 '13 at 02:00

score 0 · Answer 1 · answered Oct 13 '13 at 00:16

0

Object reference not set to an instance of an object.

Means that an object is null, or not assigned.

Hover over the variable while running or use a breakpoint, and check if map or map.pictureBox1 are null

You need to make sure that you set your map to something before you use it, and from the given code I cannot give the specific reason for the error.

answered Oct 13 '13 at 00:16

Cyral

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Since I set map to something in program.cs, it should have that error. map is null anyways so i don't know what to do. – Xfrogman43 Oct 13 '13 at 00:49

score 0 · Answer 2 · answered Oct 13 '13 at 01:20

0

You're calling Application.Run(new Form1()); before form2 = new Form2();

You need to put form2 = new Form2(); before Application.Run(new Form1());.

I'm Assuming your refresh code is being called from that instance of Form1.

answered Oct 13 '13 at 01:20

Brad

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I did that and it still says"form2" is null. – Xfrogman43 Oct 13 '13 at 18:55

score 0 · Answer 3 · answered Oct 13 '13 at 21:08

You are getting a NullReferenceException which generally occurs when you try to access an object having no reference. Generally speaking when the object is null.

In this case form2 is null.

Application.Run is a blocking call. When you call this method it opens the form passed in parameter and stays blocked there until the form closes. So,

form2 = new Form2();

This line of code does not execute and you get a null form2. You can simply resolve the problem by simply reverting the lines like this,

form2 = new Form2();
Application.Run(new Form1());

How to refresh picturebox with program.cs?

3 Answers3