Objects passed by parameter

Question

If a object is passed by parameter, does the method work with the real object or with a copy of the object.

I have a data-object where data is added every 100ms.
I like to save the data of this every 5 seconds.
If I pass the dataobject like this.

SaveData(dataobject)

Do values added in the main thread affect the object in the SaveData method ?

Answer 1

Variables are just addresses in your memory. Every thread - when they want to use this variable - refers to this address. So it doesn't matter what thread you're on, data will be changed.

Answer 2

If you pass complex type to method you use original value. If you pass primitive type you pass copy of it.

Answer 3

Yes, I understand that.

But I like to know. If data is added to a object in the main-thread. Does this affect the object that is passed as parameter.

My measuring points are added 10 every second.
I like to make a back-up every 5 seconds.
After the save method is called, there are easily 10 measuring points added to the object before it is finally saved to a file.

Are those data-points saved or Are those only in the main thread ?