Calling a "Method?" from two locations help

pumper

Member
Joined
May 12, 2016
Messages
14
Programming Experience
1-3
You can tell from my question I am new at this but here goes:
Here is the Method I call:
        private void DisplayRecord(string[,] myRecords, int currentRecord, int Records)//myRecords start at 0,  ie currentRecord = 0
        {
            
            textBox1.Text = " ";
            textBox1.Text = myRecords[currentRecord, 1].Trim();

            textBox2.Text = " ";
            textBox2.Text = myRecords[currentRecord, 2].Trim();

            textBox3.Text = " ";
            string DenS = " ";
            myRecords[0, 3] = myRecords[currentRecord, 3].Trim();
            DenS = DencryptString(myRecords[0, 3]);
            textBox3.Text = textBox3.Text + DenS;

            textBox4.Text = Convert.ToString(currentRecord);
            textBox5.Text = Convert.ToString(Records);

        }

I call it using this from my form my Form1.cs:
            //BRING ALL THE RECORDS INTO AN ARRAY THEN DISPLAY AS NEEDED?????
            string S;//???
            string S1, S2, S3;
            var myRecords = new string[Records, 4];
            // Read the file and display it line by line.  THE RECORD ONLY HAS 3 LINES
            using (StreamReader sr = new StreamReader(path + "\\MyData.txt"))
            {
                for (int i = 0; i < Records; i = i + 1)
                {
                    S = Convert.ToString(i);
                    myRecords[i, 0] = S;
                    S1 = sr.ReadLine();
                    myRecords[i, 1] = S1;
                    S2 = sr.ReadLine();
                    myRecords[i, 2] = S2;
                    S3 = sr.ReadLine();
                    myRecords[i, 3] = S3;
                }
            }

     
            currentRecord = 5;//FIRST RECORD IS AT 0
            DisplayRecord(myRecords, currentRecord, Records);

It works as I expected, now the call from another Method:
        private void button8_Click(object sender, EventArgs e)
        {
            //Go to first record
            currentRecord = 0;//FIRST RECORD IS AT 0
            DisplayRecord(myRecords, currentRecord, Records);
        }

This is what does not work, I get this:



I don't know how to troubleshoot this.
 
Last edited by a moderator:
NullReferenceException was unhandled

I forgot to add this to my original post.
 

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A NullReferenceException occurs when you try to access a member of an object that doesn't exist. On this line:
textBox1.Text = myRecords[currentRecord, 1].Trim();
you're trying to get a String from the 'myRecords' array and then call its Trim method. Presumably that element is null, hence the NullReferenceException.

By the way, what's the point of setting the Text of a TextBox to a single space when you then set it to something else immediately afterwards?
 
Thanks for the tip about Trim()

myRocords array is definitely null when called from button8_Click.

When I call DisplayRecord(myRecords, currentRecord, Records); from anywhere in the Form1_Load
routine all is good, when I call it from the button8_Click it does not work. My myRecords array is null

I guess I need help on how to keep my array from being null

I thought this:
public string[,] myRecords { get; private set; }
public int Records { get; private set; }
public int currentRecord { get; private set; }
that I set at the beginning would make it public for other methods to call

What am I missing?
 
I think the issue is that you have several variables named "myRecords". It looks like you have one declared at the class level and then several declared locally. If you have a 'myRecords' variable at the class level then you should just refer to that variable all the time and get rid of all the others, including the parameter to the DisplayRecord method.
 
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