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Downcasting in Java
Upcasting is allowed in Java, however downcasting gives a compile error.
11 Answers
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What is the difference between the | and || or operators?
...lways used || (two pipes) in OR expressions, both in C# and PHP. Occasionally I see a single pipe used: | . What is the difference between those two usages? Are there any caveats when using one over the other or are they interchangeable?
...
What is the facade design pattern?
... design pattern is a common way of solving a recurring problem. Classes in all design patterns are just normal classes. What is important is how they are structured and how they work together to solve a given problem in the best possible way.
The Facade design pattern simplifies the interface to a...
Using DNS to redirect to another URL with a path [closed]
...mail.foo.com"
under Properties -> Static Website Hosting, set "redirect all requests to: mail.google.com/a/foo.com"
in route53, create an A record "mail.foo.com"
enable "alias", and set alias target to the "mail.foo.com" bucket
not a pure DNS solution, but it works ;)
But be aware of, the redi...
Maximum number of threads per process in Linux?
...a limit on the total number of processes on the system (threads are essentially just processes with a shared address space on Linux) which you can view like this:
cat /proc/sys/kernel/threads-max
The default is the number of memory pages/4. You can increase this like:
echo 100000 > /proc/sys...
efficient way to implement paging
...irect paging in the SQL engine.
Giving you an example, I have a db table called mtcity and I wrote the following query (work as well with linq to entities):
using (DataClasses1DataContext c = new DataClasses1DataContext())
{
var query = (from MtCity2 c1 in c.MtCity2s
select c1)...
In which order do CSS stylesheets override?
...
Actually, !important participates directly in the cascade, and has nothing to do with specificity. Specificity is related to selectors, whereas !important is used with property declarations. (So you're right in saying that the ru...
Rails: How to reference images in CSS within Rails 4
... don't have the proper name adjusted. Here's what I mean. I have a file called logo.png. Yet when it shows up on heroku it is viewed as:
...
What's a good way to overwrite DateTime.Now during testing?
...
My preference is to have classes that use time actually rely on an interface, such as
interface IClock
{
DateTime Now { get; }
}
With a concrete implementation
class SystemClock: IClock
{
DateTime Now { get { return DateTime.Now; } }
}
Then if you want, you ca...
Bytes of a string in Java
...re interested in for your case, as the argument to getBytes(). And don't fall into the trap of assuming that UTF-8 represents every character as a single byte, as that's not true either:
final String interesting = "\uF93D\uF936\uF949\uF942"; // Chinese ideograms
// Check length, in characters
Sys...