Browse questions answered by Jon Skeet

Java downcast in clone

Lets say that Class B extends class A and class A is Cloneable as follows: public class A implements Cloneable { public Object clone() throws CloneNotSupportedException { ...

Ultimately, this is using Object.clone() to create the object - and that's guaranteed to create a new object of the same execution-time type as the object it's called on: The method clone for class Object performs a specific cloning... more 9/27/2013 9:27:15 AM

Are elements in a .NET's Dictionary sequential?

Say, if I create a dictionary like this: Dictionary<string, MyClass> dic = new Dictionary<string, MyClass>(); dic.add("z1", val1); dic.add("abc9",...

Am I guaranteed to have these values retrieved as such: "z1", "abc9", "abc8", "ABC1"? Absolutely not. Always treat Dictionary<,> as an unordered collection of key/value pairs. Even though as an implementation detail you'll... more 9/26/2013 9:05:22 PM

Aborting the thread from inside the same thread

I created a thread A and decided to abort it from inside the thread A. Is that possible? If so how can I do that? Thanks for the help!

Sure, you can do: Thread.CurrentThread.Abort(); Arguably aborting the current thread is the only kind of abort that's safe, as it's the only thread you really know about in terms of what it's doing. This is what HttpResponse.End does,... more 9/26/2013 7:50:10 PM

static variable vs non static variable

I have defined an object and declared a static variable i. In the get() method, when I try to print the instance and class variable, both print the same value. Isn't this.i an...

No, there's only one variable - you haven't declared any instance variables. Unfortunately, Java lets you access static members as if you were accessing it via a reference of the relevant type. It's a design flaw IMO, and some IDEs (e.g.... more 9/26/2013 6:31:41 PM

BeginInvoke copy parameter

Just try to learn Invoke/BeginInvoke, I encountered in that problem. // Update UI public void UpdateForm(string value) { txtLog.AppendText(value + "\r\n"); ...

maybe "row" can be behavior like a shared variable rather than Yes, the row variable is captured - so whenever it's read, it's the latest value that's read. You should put the variable declaration inside the loop: while... more 9/26/2013 6:19:40 PM

c# Is it possible get a reference of an object, get the object itself and change it, instead of assinging to a new object?

I'm just curious if something like that is possible in c#. I don't know why would anybody want to do it, but it's still interesting if that can be done.: public class Test { ...

If you mean "can I change the value of a to refer to a different object, simply by changing the value of b?" then the answer is no. It's important to understand that the value of a variable is never an object - always either a value type... more 9/26/2013 6:12:30 PM

What is the correct word for a type shorthand in .NET?

For example: 100M is decimal 100l is long I wanted to find one for a unit, so I don't have to type (uint) 123 all the time and I realised I didn't know what word to search for.

If you're just talking about terminology, literal is a value specified directly in source, such as: 10 10M 100L "this is a regular string literal" @"this is a verbatim string literal" '\u000' '\n' 'X' A numeric... more 9/26/2013 4:00:33 PM

Check an object is not null before iterating over it

I'm getting an error System.ArgumentNullException: Value cannot be null. on the following: foreach (var pmt in payment.NewInvoiceViewModels .Where(x => x.PaymentReceived...

You've got the null-coalescing operator in the wrong place - currently you're calling Where on payment.NewInvoiceModels unconditionally and then checking whether the result will be null... it never will be (Where simply doesn't return... more 9/26/2013 1:38:43 PM

How to make this unit test independent?

One of unit test best practices is to make each test independent to all the others. Lets say I want to test add() method of a BoundedPriorityBlockingQueue custom class: public...

What is the best practice in this situation? Just suck it up, bearing in mind that tests are meant to serve you, not the other way round. Will your tests break if something goes horribly wrong? Yes. Will it be clear where the... more 9/26/2013 12:44:27 PM

Calculate difference between two dates returns a negative number

I am trying to calculate how many days there are between different dates. Like the topic says, I'm getting a negative value. I guess I could just take the absolute value, but the...

I guess I could just take the absolute value, but the fact that it returns a negative value, makes me doubt if the calculations are correct. Why? nextDay is earlier than previousDay, so of course subtracting previousDay will give a... more 9/26/2013 12:38:46 PM