Object reference not set to an instance of an object

[kaywai]

Hi,

I got this error message "Error on calling 'OnBarUpdate' method on bar 12: Object reference not set to an instance of an object."

What does this actually mean?

Here's the code:-

protected override void OnBarUpdate()
{
if (CurrentBar < (level*2 + 10)) return;

// Identify the first pivot low
if((Low[1] < Low[0]) && (Low[1] < Low[2]))
{
DemandPoint0 = Low[1];
DemandPoint0Y = 1;
Draw.Dot(this, "DPDot", true, DemandPoint0Y, DemandPoint0, Brushes.Red, true);

}

// Hunting for a lower pivot low that has already occurred which meets the same pivot low condition and to draw a ray connecting the 2 points
for( int x = 2; x <= 100; x++)
{
if ((Low[x] < Low[x-1]) && (Low[x] < Low[x+1]))
{
if (Low[x] < DemandPoint0)
{
Draw.Ray(this, "DPL1", true, x, Low[x], DemandPoint0Y, DemandPoint0, Brushes.Pink, DashStyleHelper.Solid, 1);
}
}
}
}

Regards
Kay Wai

[bltdavid]

In most cases, that error means you have a logic error in your code.
Somewhere, somehow, your code is trying to access something
that is not defined.

Unfortunately, 'not defined' can mean most anything -- in your case,
it looks like you're trying to access Low[x] where the 'x' value is
simply too large. For Series variables, such as High, Low, etc,
the index value 'x' is known as the 'BarsAgo' index, and it should
never be greater than the current value of CurrentBar.

-=o=-

What is the initial value of your 'level' variable?
You don't show that. I'm guessing it is '1'.

Why '1'?
Because on the 12th bar the error occurs.

Where is the error?
Inside your 'for' loop. The loop wants to look back 100 bars to find
a previous pivot low, I presume.

The logic error in your code is right there.
Why? Because when there are only 12 bars on the chart, you can't
ask the code to access the 13th bar ago -- doing so results in the
error you're getting.

There is nothing wrong with looking back 100 bars to do what you
want to do -- but it is up to you to add guard code to make sure
enough bars exist to prevent trying to access non-existent bars.

That is, when CurrentBar is 12, accessing Low[x] where x > 12
means you're trying to access a non-existent bar -- and you'll get
an error.

How to fix it?

Try changing this line,
for (int x = 2; x <= 100; x++)

to something like this,
for (int x = 2; x <= Math.Max(CurrentBar-1, 100); x++)

That Math.Max() is your 'guard code', making sure enough bars exist, so
that accessing Low[x] or Low[x-1] or Low[x+1] doesn't fail.

Make sense?

[NinjaTrader_ChelseaB]

Hello kaywai,

The error 'Object reference not set to an instance of an object' means that you are using a variable with no object assigned to it (a null value).
An object reference is a variable. 'Not set to an instance of an object' means nothing was assigned to that variable.
You will need to check for null before using any variable that be null.

https://ninjatrader.com/support/forum/forum/ninjatrader-8/strategy-development/1107472-entryorder-null-error?p=1107522#post1107522

[kaywai]

bltdavid thank you very much. that was very helpful and it did the job!

[jeronymite]

kaywai You should also consider using BarsRequiredToTrade: https://ninjatrader.com/support/help...redtotrade.htm

At its simplest, you need only include this as the first line in OnBarUpdate: if (CurrentBar < BarsRequiredToTrade) return;

Thanks.

[kaywai]

Thank you jeronymite. Will take a look.