There is a method [classOf][1] in `scala.Predef` that retrieves the runtime representation of a class type.

    val stringClass = classOf[String]

You can use the `getClass` method to get the class object of an instance at runtime in the same manner as Java

    scala&gt; val s = &quot;hello world&quot;
    s: String = hello world
    
    scala&gt; s.getClass
    res0: Class[_ &lt;: String] = class java.lang.String


  [1]: http://www.scala-lang.org/api/current/scala/Predef$.html#classOf[T]:Class[T]

I&#39;ve been taught that &quot;assembly&quot; is what you write in your files, to have your &quot;assembler&quot; convert it into binary code.

But I see these two terms mixed and matched in various works. I&#39;ve even heard that you write &quot;assembler&quot;, after which an &quot;assemblator&quot; makes it executable.

Tell me, please, what&#39;s the right words to use?

&quot;Assembly&quot; vs. &quot;Assembler&quot;

My questions is: Is there a good solution to use regular expression in GWT?

I&#39;m not satisfied with the use of String.split(regex) for example. GWT translates the Code to JS and then uses the regex as a JS regex. But I cannot use something like the Java Matcher or Java Pattern. But I would need these for group matching.

Is there any possibility or library?

I tried Jakarta Regexp, but I had other problems because GWT doesn&#39;t emulate all methods of the Java SDK this library uses. 

I want to be able to use something like this on the client side:

    // Compile and use regular expression
    Pattern pattern = Pattern.compile(patternStr);
    Matcher matcher = pattern.matcher(inputStr);
    boolean matchFound = matcher.find();
		    
    if (matchFound) {
        // Get all groups for this match
        for (int i=0; i&lt;=matcher.groupCount(); i++) {
            String groupStr = matcher.group(i);
            System.out.println(groupStr);
        }
    } 

Regular Expressions and GWT

How do I get an instance of `Class` in Scala? In Java, I can do this:

    Class&lt;String&gt; stringClass = String.class;

What would be the equivalent in Scala?

What is the Scala equivalent of Java&#39;s ClassName.class?

How do I get an instance of <code>Class</code> in Scala? In Java, I can do this:
<pre><code class="hljs language-vbnet">Class&#x3C;String> stringClass = String.class;
</code></pre>
What would be the equivalent in Scala?

What are the precise rules for when you can omit (omit) parentheses, dots, braces, = (functions), etc.?

For example, 

    (service.findAllPresentations.get.first.votes.size) must be equalTo(2).

* `service` is my object
* `def findAllPresentations: Option[List[Presentation]]`
* `votes` returns `List[Vote]`
* *must* and *be* are both functions of specs

Why can&#39;t I go:

    (service findAllPresentations get first votes size) must be equalTo(2)

?

The compiler error is:

&gt; &quot;RestServicesSpecTest.this.service.findAllPresentations
&gt; of type
&gt; Option[List[com.sharca.Presentation]]
&gt; does not take parameters&quot;

Why does it think I&#39;m trying to pass in a parameter? Why must I use dots for every method call?

Why must `(service.findAllPresentations get first votes size)` be equalTo(2) result in:

&gt; &quot;not found: value first&quot;

Yet, the &quot;must be equalTo 2&quot; of
`(service.findAllPresentations.get.first.votes.size)` must be equalTo 2, that is, method chaining works fine? - object chain chain chain param.

I&#39;ve looked through the Scala book and website and can&#39;t really find a comprehensive explanation.

Is it in fact, as Rob H explains in Stack Overflow question *[Which characters can I omit in Scala?][1]*, that the only valid use-case for omitting the &#39;.&#39; is for &quot;operand operator operand&quot; style operations, and not for method chaining?

  [1]: https://stackoverflow.com/questions/1006967/scala-which-characters-can-i-omit


What are the precise rules for when you can omit parenthesis, dots, braces, = (functions), etc.?

Can Scala be used to script a Java application?

I need to load a piece of Scala code from Java, set up an execution scope for it (data exposed by the host application), evaluate it and retrieve a result object from it. 

The Scala documentation shows how easy it is to call compiled Scala code from Java (because it gets turned into to regular JVM bytecode).

But how can I evaluate a Scala expression on the fly (from Java or if that is easier, from within Scala) ? 

For many other languages, there is the javax.scripting interface. Scala does not seem to support it, and I could not find anything in the Java/Scala interoperability docs that does not rely on ahead-of-time compilation.





&quot;eval&quot; in Scala

`Option` monad is a great expressive way to deal with something-or-nothing things in Scala. But what if one needs to log a message when &quot;nothing&quot; occurs? According to the Scala API documentation,

&gt; The Either type is often used as an
&gt; alternative to scala.Option where Left
&gt; represents failure (by convention) and
&gt; Right is akin to Some.

However, I had no luck to find best practices using Either or good real-world examples involving Either for processing failures. Finally I&#39;ve come up with the following code for my own project:

        def logs: Array[String] = {
            def props: Option[Map[String, Any]] = configAdmin.map{ ca =&gt;
                val config = ca.getConfiguration(PID, null)
                config.properties getOrElse immutable.Map.empty
            }
            def checkType(any: Any): Option[Array[String]] = any match {
                case a: Array[String] =&gt; Some(a)
                case _ =&gt; None
            }
            def lookup: Either[(Symbol, String), Array[String]] =
                for {val properties &lt;- props.toRight(&#39;warning -&gt; &quot;ConfigurationAdmin service not bound&quot;).right
                     val logsParam &lt;- properties.get(&quot;logs&quot;).toRight(&#39;debug -&gt; &quot;&#39;logs&#39; not defined in the configuration&quot;).right
                     val array &lt;- checkType(logsParam).toRight(&#39;warning -&gt; &quot;unknown type of &#39;logs&#39; confguration parameter&quot;).right}
                yield array

            lookup.fold(failure =&gt; { failure match {
                case (&#39;warning, msg) =&gt; log(LogService.WARNING, msg)
                case (&#39;debug, msg) =&gt;   log(LogService.DEBUG, msg)
                case _ =&gt;
            }; new Array[String](0) }, success =&gt; success)
        }

(Please note this is a snippet from a real project, so it will not compile on its own)

I&#39;d be grateful to know how you are using `Either` in your code and/or better ideas on refactoring the above code.

Using Either to process failures in Scala code

In Scala, if I define a method called `apply` in a class or a top-level object, that method will be called whenever I append a pair a parentheses to an instance of that class, and put the appropriate arguments for `apply()` in between them. For example:

    class Foo(x: Int) {
        def apply(y: Int) = {
            x*x + y*y
        }
    }

    val f = new Foo(3)
    f(4)   // returns 25

So basically, `object(args)` is just syntactic sugar for `object.apply(args)`.

How does Scala do this conversion?

Is there a globally defined implicit conversion going on here, similar to the implicit type conversions in the Predef object (but different in kind)? Or is it some deeper magic? I ask because it seems like Scala strongly favors consistent application of a smaller set of rules, rather than many rules with many exceptions. This initially seems like an exception to me.


How does Scala&#39;s apply() method magic work?

Is there a nice way I can convert a Scala `case class` instance, e.g.

    case class MyClass(param1: String, param2: String)
    val x = MyClass(&quot;hello&quot;, &quot;world&quot;)

into a mapping of some kind, e.g.

    getCCParams(x) returns &quot;param1&quot; -&gt; &quot;hello&quot;, &quot;param2&quot; -&gt; &quot;world&quot;
    
Which works for any case class, not just predefined ones. I&#39;ve found you can pull the case class name out by writing a method that interrogates the underlying Product class, e.g.

    def getCCName(caseobj: Product) = caseobj.productPrefix 
    getCCName(x) returns &quot;MyClass&quot;

So I&#39;m looking for a similar solution but for the case class fields. I&#39;d imagine a solution might have to use Java reflection, but I&#39;d hate to write something that might break in a future release of Scala if the underlying implementation of case classes changes.
    
Currently I&#39;m working on a Scala server and defining the protocol and all its messages and exceptions using case classes, as they are such a beautiful, concise construct for this. But I then need to translate them into a Java map to send over the messaging layer for any client implementation to use. My current implementation just defines a translation for each case class separately, but it would be nice to find a generalised solution.

Content Type	Original Author	Original Content on Stackoverflow
Question	Daniel C. Sobral	View Question on Stackoverflow
Solution 1 - Scala	oxbow_lakes	View Answer on Stackoverflow

What is the Scala equivalent of Java's ClassName.class?

Scala Problem Overview

Scala Solutions

Solution 1 - Scala

Regular Expressions and GWT

"Assembly" vs. "Assembler"

Attributions