Browse questions answered by Jon Skeet

Limits of static method references in Java 8

I'm trying to use method references to capture method invocations and am hitting some limitations. This works fine: <T> void capture(Function<T, ?> in) { } private...

There are two problems here: You're using Function, which has to return something. setBar doesn't return anything. Function only takes a single input, but you've got two inputs: the Foo you'd call setBar on, and the String argument you'd... more 5/21/2014 9:38:59 PM

Object values and local values in arithmetic

So I was trying to perform a simple arithmetic on values within and object 'currentUser' in my one 'pricingAction' class. The code should add the two volume values(doubles) and...

Let's simplify the code a little so it's easier to read: foo.setX(foo.getX() + foo.getY()); foo.setY(foo.getX() + foo.getY()); Now suppose we start with foo.X = 10, foo.Y = 20. The first statement will initially compute foo.X + foo.Y -... more 5/21/2014 7:59:32 PM

printing instance data using static properties

I've written some list of classes, here's the code I used to initialize class public class Album { static public int IDNumber { get; set; } static public...

All your properties are static - that means that they are related to the type rather than any one instance of the type. (It's not that the values are "shared by all instance" - it's that they're completely unrelated to any instance.) You... more 5/21/2014 7:51:18 PM

c# method name expected INotifypropertyChanged

I'm running into a problem. I'm a VB.net programmer and I'm trying to learn C#. On many VB projects that I have done I've always used a viewModelBase class where I can notify my...

It sounds like you're just missing the fact that indexer syntax in C# is [key]. I suspect you want: if (TypeDescriptor.GetProperties(this)[propertyName] == null) That's first calling the GetProperties method, to find the... more 5/21/2014 7:45:19 PM

Formatting a double value within the toString() method (with respect to the decimal)

This is a fairly simple question. I have a class of objects Item which constructs the objects declared in the TestItem class. The overridden toString() method utilises the...

You can use String.format to control the format in general. Unfortunately I can't see any way of combining that with a custom pattern directly, but you can compose them. For example: import java.math.*; import java.text.*; public class... more 5/21/2014 7:26:32 PM

Java get parent of parent

This is a very similar question to this one: How to get just the parent directory name of a specific file But there he wanted to get just the closest Parent directory, what I...

getParent() returns a String - you can't call getParent() on a String. Instead, you want getParentFile(): File grandparent = file.getParentFile().getParentFile(); more 5/21/2014 6:32:48 PM

Using Moq with overloaded method

Why doesn't my Moq Test resolve to the appropriate Method. Calling the Service in my Test: var service = new EmployeeService(mockScoreRep); Uses the following Method public...

I suspect the problem is that you want the mock object, not the wrapper: var service = new EmployeeService(mockScoreRep.Object); In other words, you want to pass an IRepository<Score> - not a... more 5/21/2014 5:43:38 PM

Type Class is a raw type. References to generic type Class<T> should be parameterized

Class activityItems work fine but i get warning "Type Class is a raw type. References to generic type Class should be parameterized". How to fix it ? Here is my code: public...

I think it may just be a case of changing this: Class activityItems = Class.forName("com.arbaz.hk." + item); to: Class<?> activityItems = Class.forName("com.arbaz.hk." + item); That way you're still not saying you know what the... more 5/21/2014 5:41:20 PM

Is it possible to make dateTime.ToString(...) return a different timezone offset?

My project is using PDFSharp to normalize creation dates in pdfs. The issue I'm having is that people in different timezones get different offset values than I do. The problem is...

No, basically zzz will always use the system default time zone. From the documentation: With DateTime values, the "zzz" custom format specifier represents the signed offset of the local operating system's time zone from UTC, measured... more 5/21/2014 5:17:05 PM

Comparison method violates its general contract, how to make it transitive?

I dont see how it is not transitive, please someone suggest me the right way. if both values are null I return 0, the two other statements are pretty obvious. Why i got...

Look at this code: if (compInt1 < compInt2) { return -1; } else if (compInt1 >= compInt2) { return 1; } else { return 0; } How do you expect that ever to return 0? What values of compInt1 and compInt2 would make both... more 5/21/2014 4:16:33 PM