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Why would an Enum implement an Interface?
I just found out that Java allows enums to implement an interface. What would be a good use case for that?
16 Answers
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Maven does not find JUnit tests to run
... Note that the surefire documentation now claims that **/*Tests.java is a default include!
– Gareth
Oct 13 '17 at 9:54
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How to implement a queue using two stacks?
...e, giving amortized constant time operations.
Here's an implementation in Java:
public class Queue<E>
{
private Stack<E> inbox = new Stack<E>();
private Stack<E> outbox = new Stack<E>();
public void queue(E item) {
inbox.push(item);
}
pu...
Sorting an ArrayList of objects using a custom sorting order
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Here's a tutorial about ordering objects:
The Java Tutorials - Collections - Object Ordering
Although I will give some examples, I would recommend to read it anyway.
There are various way to sort an ArrayList. If you want to define a natural (default) ordering, then...
Why can a class not be defined as protected?
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Since there's no such concept as 'subpackage' or 'package-inheritance' in Java, declaring class protected or package-private would be the same thing.
You can declare nested and inner classes as protected or private, though.
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Math.random() explanation
This is a pretty simple Java (though probably applicable to all programming) question:
5 Answers
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Any reason to clean up unused imports in Java, other than reducing clutter?
Is there any good reason to avoid unused import statements in Java? As I understand it, they are there for the compiler, so lots of unused imports won't have any impacts on the compiled code. Is it just to reduce clutter and to avoid naming conflicts down the line?
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URLEncoder not able to translate space character
...ts the HTML Specifications for how to encode URLs in HTML forms.
From the javadocs:
This class contains static methods for
converting a String to the
application/x-www-form-urlencoded MIME
format.
and from the HTML Specification:
application/x-www-form-urlencoded
Forms submit...
Java regex email
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FWIW, here is the Java code we use to validate email addresses. The Regexp's are very similar:
public static final Pattern VALID_EMAIL_ADDRESS_REGEX =
Pattern.compile("^[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,6}$", Pattern.CASE_INSENSITIVE)...
Difference between object and class in Scala
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tl;dr
class C defines a class, just as in Java or C++.
object O creates a singleton object O as instance of some anonymous class; it can be used to hold static members that are not associated with instances of some class.
object O extends T makes the object O an inst...