Nullreferenceexception in Winforms code

Question

I believe it’s a bug not the code, but the compiler...

When I eat this area of code, the error always goes to the next variable, or method.

Behold:

Part of the code:

                grpBoxMDeck[i] = new System.Windows.Forms.GroupBox()
                {
                    Location = new System.Drawing.Point(76, yG),
                    Size = new System.Drawing.Size(536, 340),
                    BackColor = System.Drawing.Color.Transparent,
                    ForeColor = corLetra,
                    Font = new System.Drawing.Font(Font.FontFamily, 8.25f, System.Drawing.FontStyle.Bold),
                    Text = string.Format("Elixir Médio: {0:f1} - Arena {1}+", elixirMedio, decks[i].Split('|')[1]).Replace(',', '.')
                };
                grpBoxMDeck[i].Click += (s, e) => pMelhoresDecks.Select();
                grpBoxMDeck[i].ContextMenuStrip = cmsGBMDecks[i];

                picImagemMDecks[i] = new System.Windows.Forms.PictureBox[8];
                byte x1 = 3, x2 = 3;

                for (byte j = 0; j < picImagemMDecks.Length; j++)
                {
                    byte copiaJ = j;
                    picImagemMDecks[i][j] = new System.Windows.Forms.PictureBox()
                    {
                        Size = new System.Drawing.Size(131, 157),
                        SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage,
                        BackColor = System.Drawing.Color.Transparent
                    };
                    if (j < 4) { picImagemMDecks[i][j].Location = new System.Drawing.Point(x1, 15); x1 += 133; }
                    else { picImagemMDecks[i][j].Location = new System.Drawing.Point(x2, 174); x2 += 133; }
                    grpBoxMDeck[i].Controls.Add(picImagemMDecks[i][j]);
                }

                pMelhoresDecks.Controls.Add(grpBoxMDeck[i]);

Any solution to this bug? It appeared out of nowhere, the code ran normally, even that last line:

pMelhoresDecks.Controls.Add(grpBoxMDeck[i]);

Now not even it runs. I tried to close and open Visual Studio and nothing!

Answer 1

Try to do this:

picImagemMDecks[i] = new System.Windows.Forms.PictureBox();

According to the documentation this is how you create a new object PictureBox.

I can’t guarantee that it will work because we don’t have all the code to know. But everything suggests that this is it.

In fact most people write like this:

picImagemMDecks[i] = new PictureBox();

I put in the Github for future reference.

And the variable pMelhoresDecks needs to be initialized with some value before using. If you didn’t do this, the value is null and nothing can be done with it but initialize it. So you have to do this before you use it. You usually initialize it next to her declaration. Find it and give it a new something there.

Some tips:

• Commenting an error code does not make the error disappear, usually causes more errors and probably harder to fix.
• Closing Visual Studio does not make the error magically disappear.
• The "never" problem is from the compiler.
• Read the documentation of what you’re using before you use it. If you don’t understand something, I see what you need to learn first.
• You’re finishing a house that has no foundation, it’s all gonna fall apart. First understand how things work, what is each thing, one step at a time, goes in the simple, one concept after another, when master something there you pass to the next. If you keep playing codes you don’t understand you’re not programming and every day you’re getting worse.