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PO
primarykey
Id
1642012
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
2
CommunityOwnedDate
2009-10-29T08:03:43.240
CreationDate
2009-10-29T06:51:01.220
FavoriteCount
0
LastActivityDate
2014-05-13T14:36:48.373
LastEditDate
2014-05-13T14:36:48.373
LastEditorUserId
2621536
OwnerUserId
189058
ParentId
1641104
PostTypeId
2
Score
18
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0
LastEditorDisplayName
text
Body
<pre><code>scala> case class Foo(id:Long, name:String) defined class Foo scala> val constructor = classOf[Foo].getConstructors()(0) constructor: java.lang.reflect.Constructor[_] = public Foo(long,java.lang.String) scala> val args = Array[AnyRef](new java.lang.Integer(1), "Foobar") args: Array[AnyRef] = Array(1, Foobar) scala> val instance = constructor.newInstance(args:_*).asInstanceOf[Foo] instance: Foo = Foo(1,Foobar) scala> instance.id res12: Long = 1 scala> instance.name res13: String = Foobar scala> instance.getClass res14: java.lang.Class[_] = class Foo </code></pre> Currently there is not much reflection support in Scala. But you can fall back to th Java Reflection API. But there are some obstacles: <ul> <li>You have to create a <code>Array[AnyRef]</code> and box your "primitive types" in the wrapper classes (<code>java.lang.Integer, java.lang.Character, java.lang.Double, ...</code>)</li> <li><code>newInstance(Object ... args)</code> gets an varargs array of <code>Object</code>, so you should give the type inferer a hint with <code>:_*</code></li> <li><code>newInstance(...)</code> returns an <code>Object</code> so you have to cast it back with <code>asInstanceOf[T]</code></li> </ul> The closest I could get to your <code>instantiate</code> function is this: <pre><code>def instantiate(clazz: java.lang.Class[_])(args:AnyRef*): AnyRef = { val constructor = clazz.getConstructors()(0) return constructor.newInstance(args:_*).asInstanceOf[AnyRef] } val instance = instantiate(classOf[MyClass])(new java.lang.Integer(42), "foo") println(instance) // prints: MyClass(42,foo) println(instance.getClass) // prints: class MyClass </code></pre> You cannot get the get class from a generic type. Java erases it (type erasure). Edit: 20 September 2012 Three years on, the <code>instantiate</code> method can be improved to return a properly typed object. <pre><code>def instantiate[T](clazz: java.lang.Class[T])(args:AnyRef*): T = { val constructor = clazz.getConstructors()(0) return constructor.newInstance(args:_*).asInstanceOf[T] } </code></pre> See <a href="http://www.nabble.com/How-do-I-get-the-class-of-a-Generic--td20873455.html" rel="noreferrer">http://www.nabble.com/How-do-I-get-the-class-of-a-Generic--td20873455.html</a>
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