Keep getting" Object reference not set to an instance of an object." for picturebox array

Question

private void radar_Tick(object sender, EventArgs e)
{
    for (int i = 0; i < 20; i++)
    {
        x[i] = Readi(0x5C850C + (0x5A4 * i));
        y[i] = Readi(0x5C8510 + (0x5A4 * i));
        players[i].Location = new Point(x[i], y[i]);
    }
}

and yeah, before that:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }
    int []x=new int[32];int []y=new int[32];
    PictureBox[] players=new PictureBox[32];    
    ...  
}
private void Form1_Load(object sender, EventArgs e)
    {
        int i = 0;
        foreach (var ctrl in this.Controls)
        {
            if (ctrl is PictureBox)
            {
                var myPicturebBox = (PictureBox)ctrl;
                players[i] = myPicturebBox;
                this.Controls.Add(players[i]);
                i++;

            }
        }
        radar.Interval = 100;
        radar.Start();
    }

What I keep getting is "Object reference not set to an instance of an object". I don't want to make new object on every timer tick, I just want to change i-th picturebox's location. Any ideas? Nulls are not x and y,null is pictebox array.(I tried adding players[i]=new PictureBox(); and it worked.That's how I know)

possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Lucas Trzesniewski, Apr 12 '15 at 23:02
What is those two x[i] and y[i], did you create two arrays **x** and **y** and initialized them? — Youssef Lourayad, Apr 12 '15 at 23:14
I guess,everything I did in radar_tick is shown in the code.What should I do if it's null? @DWright — Turus, Apr 12 '15 at 23:15
Well, first is it null? Or per @Lourayad, is `x` or `y` null. First thing to do is to figure out what is null. — DWright, Apr 12 '15 at 23:17

Youssef Lourayad · Accepted Answer · 2015-04-13T00:23:19.740

2

If you already have 32 PictureBox objects and you want to change their Locations, you need to make each of the players array members reference a PictureBox.

int i = 0;
foreach (var ctrl in this.Controls)
{
    if (ctrl is PictureBox)
    {
        var myPicturebBox = (PictureBox)ctrl;
        players[i] = myPictureBox;
        i++;
    }
}

Now your array members reference all of the PictureBox objects in your Form.

Edit

Since your PictureBox objects are all created programmatically, you have to instatiate them before you can use them, like this:

PictureBox myPictureBox = new PictureBox();

Now you need to add the PictureBox to the Controls collection of the Form:

this.Controls.Add(myPictureBox)

Then you can use the previous code, do this for all of the PictureBoxes using a loop.

edited Apr 13 '15 at 00:23

answered Apr 12 '15 at 23:36

Youssef Lourayad

337
3
14

This into radar_Tick?I've tried this,but it always creates another picturebox,and as I mentioned,I don't want new picturebox,I just want to change it's location. – Turus Apr 12 '15 at 23:39
Then you need to fill your `players` array with the `PictureBox` objects that already exist. – Youssef Lourayad Apr 12 '15 at 23:40
Does it mean I have to add 32 pictureBoxes on my Form?Isn't there any easier way?Huh – Turus Apr 12 '15 at 23:43
No, not in `radar_Tick`, put it in `Form_Load` or somewhere similar. – Blorgbeard Apr 12 '15 at 23:47
You added the PictureBoxes from the designer ? or were they created programmatically ? – Youssef Lourayad Apr 13 '15 at 00:16
Then you probably didn't instatiate them with the `new` keyword, did you? And you need to add them to the `Form`'s `Controls ` collection. – Youssef Lourayad Apr 13 '15 at 00:18
Didn't see u have edited.It worked by the way,thank u so much. – Turus Apr 13 '15 at 00:23

Keep getting" Object reference not set to an instance of an object." for picturebox array

1 Answers1