I have a Scala annotation with parameters, some with default values:
case class A(x: String, y: Option[String] = None, z: Option[Boolean] = None)
extends scala.annotation.StaticAnnotation
The goal is to annotate classes with this, and collect annotation parameters at runtime.
If I specify annotation parameters using positional notation, things work fine:
#A("xx", None, Some(true)) case class X()
import scala.reflect.runtime.universe._
import scala.tools.reflect.ToolBox
val m = runtimeMirror(getClass.getClassLoader)
val t = m.mkToolBox()
val x = typeOf[X].typeSymbol.asClass.annotations.find(_.tree.tpe =:= typeOf[A]).get
println(t.eval(t.untypecheck(x.tree)).asInstanceOf[A])
This would print A(xx,None,Some(true)), as it should.
The following, however, would not work:
#A("x", z = Some(true)) case class Y()
val y = typeOf[Y].typeSymbol.asClass.annotations.find(_.tree.tpe =:= typeOf[A]).get
println(t.eval(t.untypecheck(y.tree)).asInstanceOf[A])
it would result in an exception I've never seen before:
java.lang.AssertionError: assertion failed: unsafe symbol x$3 (child of <none>) in runtime reflection universe
at scala.reflect.internal.Symbols$Symbol.<init>(Symbols.scala:205)
at scala.reflect.internal.Symbols$TermSymbol.<init>(Symbols.scala:2768)
at scala.reflect.internal.Symbols$StubTermSymbol.<init>(Symbols.scala:3524)
at scala.reflect.internal.Symbols$class.newStubSymbol(Symbols.scala:192)
at scala.reflect.internal.SymbolTable.newStubSymbol(SymbolTable.scala:16)
at scala.reflect.internal.Symbols$Symbol.newStubSymbol(Symbols.scala:521)
at scala.reflect.internal.pickling.UnPickler$Scan.readExtSymbol$1(UnPickler.scala:258)
at scala.reflect.internal.pickling.UnPickler$Scan.readSymbol(UnPickler.scala:286)
at scala.reflect.internal.pickling.UnPickler$Scan.readSymbolRef(UnPickler.scala:651)
at scala.reflect.internal.pickling.UnPickler$Scan.readNonEmptyTree(UnPickler.scala:610)
at scala.reflect.internal.pickling.UnPickler$Scan.readTree(UnPickler.scala:623)
at scala.reflect.internal.pickling.UnPickler$Scan$$anonfun$readAnnotArg$1.apply(UnPickler.scala:471)
at scala.reflect.internal.pickling.UnPickler$Scan$$anonfun$readAnnotArg$1.apply(UnPickler.scala:471)
at scala.reflect.internal.pickling.UnPickler$Scan.at(UnPickler.scala:179)
at scala.reflect.internal.pickling.UnPickler$Scan.readAnnotArg(UnPickler.scala:471)
at scala.reflect.internal.pickling.UnPickler$Scan.readAnnotationInfo(UnPickler.scala:505)
at scala.reflect.internal.pickling.UnPickler$Scan.readSymbolAnnotation(UnPickler.scala:517)
at scala.reflect.internal.pickling.UnPickler$Scan.run(UnPickler.scala:97)
at scala.reflect.internal.pickling.UnPickler.unpickle(UnPickler.scala:38)
at scala.reflect.runtime.JavaMirrors$JavaMirror.unpickleClass(JavaMirrors.scala:619)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter$$anonfun$complete$1.apply$mcV$sp(SymbolLoaders.scala:28)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter$$anonfun$complete$1.apply(SymbolLoaders.scala:25)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter$$anonfun$complete$1.apply(SymbolLoaders.scala:25)
at scala.reflect.internal.SymbolTable.slowButSafeEnteringPhaseNotLaterThan(SymbolTable.scala:263)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.complete(SymbolLoaders.scala:25)
at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1535)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.scala$reflect$runtime$SynchronizedSymbols$SynchronizedSymbol$$super$info(SynchronizedSymbols.scala:168)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anonfun$info$1.apply(SynchronizedSymbols.scala:127)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anonfun$info$1.apply(SynchronizedSymbols.scala:127)
at scala.reflect.runtime.Gil$class.gilSynchronized(Gil.scala:19)
at scala.reflect.runtime.JavaUniverse.gilSynchronized(JavaUniverse.scala:16)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$class.gilSynchronizedIfNotThreadsafe(SynchronizedSymbols.scala:123)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.gilSynchronizedIfNotThreadsafe(SynchronizedSymbols.scala:168)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$class.info(SynchronizedSymbols.scala:127)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.info(SynchronizedSymbols.scala:168)
at scala.reflect.internal.Symbols$Symbol.initialize(Symbols.scala:1680)
at scala.reflect.internal.Symbols$Symbol.annotations(Symbols.scala:1847)
at test.TestAnnotation$.delayedEndpoint$test$TestAnnotation$1(TestAnnotation.scala:18)
at test.TestAnnotation$delayedInit$body.apply(TestAnnotation.scala:12)
at scala.Function0$class.apply$mcV$sp(Function0.scala:34)
at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.collection.immutable.List.foreach(List.scala:392)
at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
at scala.App$class.main(App.scala:76)
at test.TestAnnotation$.main(TestAnnotation.scala:12)
at test.TestAnnotation.main(TestAnnotation.scala)
Exception in thread "main" java.lang.RuntimeException: error reading Scala signature of test.Y: assertion failed: unsafe symbol x$3 (child of <none>) in runtime reflection universe
at scala.reflect.internal.pickling.UnPickler.unpickle(UnPickler.scala:46)
at scala.reflect.runtime.JavaMirrors$JavaMirror.unpickleClass(JavaMirrors.scala:619)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter$$anonfun$complete$1.apply$mcV$sp(SymbolLoaders.scala:28)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter$$anonfun$complete$1.apply(SymbolLoaders.scala:25)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter$$anonfun$complete$1.apply(SymbolLoaders.scala:25)
at scala.reflect.internal.SymbolTable.slowButSafeEnteringPhaseNotLaterThan(SymbolTable.scala:263)
at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.complete(SymbolLoaders.scala:25)
at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1535)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.scala$reflect$runtime$SynchronizedSymbols$SynchronizedSymbol$$super$info(SynchronizedSymbols.scala:168)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anonfun$info$1.apply(SynchronizedSymbols.scala:127)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anonfun$info$1.apply(SynchronizedSymbols.scala:127)
at scala.reflect.runtime.Gil$class.gilSynchronized(Gil.scala:19)
at scala.reflect.runtime.JavaUniverse.gilSynchronized(JavaUniverse.scala:16)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$class.gilSynchronizedIfNotThreadsafe(SynchronizedSymbols.scala:123)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.gilSynchronizedIfNotThreadsafe(SynchronizedSymbols.scala:168)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$class.info(SynchronizedSymbols.scala:127)
at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.info(SynchronizedSymbols.scala:168)
at scala.reflect.internal.Symbols$Symbol.initialize(Symbols.scala:1680)
at scala.reflect.internal.Symbols$Symbol.annotations(Symbols.scala:1847)
at test.TestAnnotation$.delayedEndpoint$test$TestAnnotation$1(TestAnnotation.scala:18)
at test.TestAnnotation$delayedInit$body.apply(TestAnnotation.scala:12)
at scala.Function0$class.apply$mcV$sp(Function0.scala:34)
at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.collection.immutable.List.foreach(List.scala:392)
at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
at scala.App$class.main(App.scala:76)
at test.TestAnnotation$.main(TestAnnotation.scala:12)
at test.TestAnnotation.main(TestAnnotation.scala)
As soon as I switch back to the positional arguments, things start working again.
Any idea on what am I facing here?
EDIT: Tried this with Scala 2.11 and 2.13, the failure and exception is consistent for both versions
Related
I'm running a gatling simulation that uses numeric input from a yml file to feed its scenario. Everything works when my numeric inputs are large enough that they cannot be parsed as instances of java.lang.Integer, but small numeric values are apparently parsed to Integers and result in a ClassCastException.
import java.io.FileInputStream
import io.gatling.core.Predef.{Feeder, Simulation}
import org.yaml.snakeyaml.Yaml
import org.yaml.snakeyaml.constructor.Constructor
import io.gatling.core.Predef.{scenario, _}
import scala.collection.JavaConversions
class TestClass extends Simulation {
val yaml = new Yaml(new Constructor(classOf[Holder]))
val holder = yaml.load(new FileInputStream("src/test/resources/data.yml")).asInstanceOf[Holder]
scenario("sim").feed(getUserEmulationFeeder(holder))
def getUserEmulationFeeder(holder:Holder) : Feeder[Long] = {
val iterable = JavaConversions.iterableAsScalaIterable(holder.numbers)
iterable.map(l => Map("userToEmulate" -> l)).iterator
}
}
data.yml has the following data:
numbers:
- 30687965369
- 31415388869
- 2
and is being deserialized into:
import scala.beans.BeanProperty
class Holder {
#BeanProperty var numbers = new java.util.ArrayList[Long]()
}
Removing the 2 fixes the ClassCastException.
The full stacktrace is:
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at io.gatling.mojo.MainWithArgsInFile.runMain(MainWithArgsInFile.java:50)
at io.gatling.mojo.MainWithArgsInFile.main(MainWithArgsInFile.java:33)
Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Long
at scala.runtime.BoxesRunTime.unboxToLong(BoxesRunTime.java:105)
at com.mercurygate.TestClass$$anonfun$getUserEmulationFeeder$1.apply(TestClass.scala:25)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
at scala.collection.Iterator$class.foreach(Iterator.scala:893)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
at scala.collection.AbstractTraversable.map(Traversable.scala:104)
at com.mercurygate.TestClass.getUserEmulationFeeder(TestClass.scala:25)
at com.mercurygate.TestClass.<init>(TestClass.scala:21)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at java.lang.Class.newInstance(Class.java:442)
at io.gatling.app.Gatling$.io$gatling$app$Gatling$$$anonfun$1(Gatling.scala:41)
at io.gatling.app.Gatling$lambda$1.apply(Gatling.scala:41)
at io.gatling.app.Gatling$lambda$1.apply(Gatling.scala:41)
at io.gatling.app.Gatling.run(Gatling.scala:92)
at io.gatling.app.Gatling.runIfNecessary(Gatling.scala:75)
at io.gatling.app.Gatling.start(Gatling.scala:65)
at io.gatling.app.Gatling$.start(Gatling.scala:57)
at io.gatling.app.Gatling$.fromArgs(Gatling.scala:49)
at io.gatling.app.Gatling$.main(Gatling.scala:43)
at io.gatling.app.Gatling.main(Gatling.scala)
... 6 more
P.S. Sorry for the complexity of the example. It's only when I combine snakeyaml, gatling, and the small input that I get the error.
I would like to load some scala class at runtime, the class are presents in my scala project.
More precisely, in the root folder of my project, I have the TmpCaseClass.scala :
class TmpHBaseCaseClass(val adresse:String,val age:Int,val nom:String,val id:Int,val salaire:Float)
I would like to compile it and use it at run time using toolBox like this :
val tb = universe.runtimeMirror(getClass.getClassLoader).mkToolBox()
val clazz = tb.compile(tb.parse("./TmpCaseClass.scala"))().asInstanceOf[Class[_]]
val ctor = clazz.getDeclaredConstructors()(0)
val instance = ctor.newInstance()
But I encounter the follwing error :
Exception in thread "main" scala.tools.reflect.ToolBoxError:
reflective compilation has failed:
illegal start of definition at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$ToolBoxGlobal.throwIfErrors(ToolBoxFactory.scala:316)
at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$ToolBoxGlobal.parse(ToolBoxFactory.scala:291)
at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$$anonfun$parse$1.apply(ToolBoxFactory.scala:417)
at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$$anonfun$parse$1.apply(ToolBoxFactory.scala:414)
at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$withCompilerApi$.liftedTree2$1(ToolBoxFactory.scala:355)
at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$withCompilerApi$.apply(ToolBoxFactory.scala:355)
at
scala.tools.reflect.ToolBoxFactory$ToolBoxImpl.parse(ToolBoxFactory.scala:414)
at Main$.delayedEndpoint$Main$1(Main.scala:17) at
Main$delayedInit$body.apply(Main.scala:13) at
scala.Function0$class.apply$mcV$sp(Function0.scala:34) at
scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:76) at
scala.App$$anonfun$main$1.apply(App.scala:76) at
scala.collection.immutable.List.foreach(List.scala:381) at
scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
at scala.App$class.main(App.scala:76) at Main$.main(Main.scala:13)
at Main.main(Main.scala)
The line 17 (where the error happens) corresponds to :
val clazz = tb.compile(tb.parse("./TmpCaseClass.scala"))().asInstanceOf[Class[_]]
How could I get rid of this error ?
1) Try to parse file contents, instead of file name.
2) Also you wont be able to cast to Class, since compilation returns Unit. You might want to put another line like scala.reflect.classTag[TmpCaseClass].runtimeClass. You can also get tree (AST) as a result of tb.parse, if that's what you need.
I am trying to get a map of name -> id from the resultset.
val isp = SQL("select id, name from internet_service_providers").map { x => x[String]("name") -> x[String]("id") }
I am unable to understand why I am getting this error.
Exception in thread "main" java.lang.NoSuchMethodError: scala.Predef$.ArrowAssoc(Ljava/lang/Object;)Ljava/lang/Object;
at anorm.SqlStatementParser$$anonfun$3.apply(SqlStatementParser.scala:43)
at anorm.SqlStatementParser$$anonfun$3.apply(SqlStatementParser.scala:43)
at scala.util.parsing.combinator.Parsers$Success.map(Parsers.scala:136)
at scala.util.parsing.combinator.Parsers$Success.map(Parsers.scala:135)
at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
at scala.util.parsing.combinator.Parsers$Parser$$anonfun$map$1.apply(Parsers.scala:242)
at scala.util.parsing.combinator.Parsers$$anon$3.apply(Parsers.scala:222)
at scala.util.parsing.combinator.RegexParsers$class.parse(RegexParsers.scala:148)
at anorm.SqlStatementParser$.parse(SqlStatementParser.scala:11)
at anorm.SqlStatementParser$$anonfun$parse$1.apply(SqlStatementParser.scala:26)
at anorm.SqlStatementParser$$anonfun$parse$1.apply(SqlStatementParser.scala:26)
at scala.util.Try$.apply(Try.scala:161)
at anorm.SqlStatementParser$.parse(SqlStatementParser.scala:26)
at anorm.package$.SQL(package.scala:40)
at com.gumgum.nativead.NativeInventoryApp$.main(NativeInventoryApp.scala:49)
at com.gumgum.nativead.NativeInventoryApp.main(NativeInventoryApp.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
I am guessing that my way of creating the map in code above might be completely wrong or there is a scala version mismatch in the libs used.
I am using scala 2.11.5 and anrom 2.4.0-M3 built with scala 2.11
First the error java.lang.NoSuchMethodError: scala.Predef$.ArrowAssoc(Ljava/lang/Object;)Ljava/lang/Object; is not from Anorm but from Predef: the -> operator is not found to build tupple, which is quite weird. I would suggest to check your scala version and dependencies, to be sure there is not several scala lib pulled.
Then if you want to turn a Row as a tuple, SqlParser.flatten can be used.
Finally as the result will be a list of tuple, .toMap can be used.
import anorm.SqlParser.{ flatten, str }
SQL("...").as((str("name") ~ str("id")).map(flatten).*).toMap
I have a number of objects (not classes) that manipulate databases, and I want to make a smaller helper class so I can do something like java my.helper.class my.database.class and execute the the run method.
For example, this compiles
trait A extends Runnable
class B extends A { def run() = println("run") }
object Test extends App {
Class.forName(args(0)).newInstance().asInstanceOf[A].run()
}
And then does what I expect.
$scala Test B
run
This also compiles
trait A extends Runnable
object B extends A { def run() = println("run") }
object Test extends App {
Class.forName(args(0)).newInstance().asInstanceOf[A].run()
}
But this happens:
$scala Test B
java.lang.InstantiationException: B
at java.lang.Class.newInstance(Class.java:418)
at Test$.delayedEndpoint$Test$1(Test.scala:9)
at Test$delayedInit$body.apply(Test.scala:8)
at scala.Function0$class.apply$mcV$sp(Function0.scala:40)
at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.collection.immutable.List.foreach(List.scala:383)
at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
at scala.App$class.main(App.scala:76)
at Test$.main(Test.scala:8)
at Test.main(Test.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at scala.reflect.internal.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:68)
at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:31)
at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:99)
at scala.reflect.internal.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:68)
at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:99)
at scala.tools.nsc.CommonRunner$class.run(ObjectRunner.scala:22)
at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:39)
at scala.tools.nsc.CommonRunner$class.runAndCatch(ObjectRunner.scala:29)
at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:39)
at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:72)
at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:94)
at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:103)
at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
Caused by: java.lang.NoSuchMethodException: B.<init>()
at java.lang.Class.getConstructor0(Class.java:2971)
at java.lang.Class.newInstance(Class.java:403)
... 28 more
Which makes sense, and I figured this would work:
$scala Test B$
java.lang.IllegalAccessException: Class Test$ can not access a member of class B$ with modifiers "private"
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:101)
at java.lang.Class.newInstance(Class.java:427)
at Test$.delayedEndpoint$Test$1(Test.scala:9)
at Test$delayedInit$body.apply(Test.scala:8)
at scala.Function0$class.apply$mcV$sp(Function0.scala:40)
at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.App$$anonfun$main$1.apply(App.scala:76)
at scala.collection.immutable.List.foreach(List.scala:383)
at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
at scala.App$class.main(App.scala:76)
at Test$.main(Test.scala:8)
at Test.main(Test.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at scala.reflect.internal.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:68)
at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:31)
at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:99)
at scala.reflect.internal.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:68)
at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:99)
at scala.tools.nsc.CommonRunner$class.run(ObjectRunner.scala:22)
at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:39)
at scala.tools.nsc.CommonRunner$class.runAndCatch(ObjectRunner.scala:29)
at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:39)
at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:72)
at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:94)
at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:103)
at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
But it also fails. I know I could just make all these static objects into classes, but that doesn't makes sense in this application, so I'm specifically looking for the elegant way to do this.
I personally think the most elegant way is to not dynamically load things like this. Is it really that difficult to specify the valid input? This allows much greater flexibility with respect to where your instances of A come from.
object Test extends App {
args(0) match {
case "B" => B
case "C" =>
val someOtherConfig = args(1)
new C(someOtherParam)
case other => throw new Exception("invalid input")
} run
}
I would use Scopt to parse parameters
I am trying to use "gdata-scala-client" import google contacts using scala.
I followed the instructions here,
This is my sample code
import com.google.gdata.Service
import com.google.gdata.data.StdAtomFeed
object Con extends App {
println("hey")
val s = new Service("comp-test-1.0", "cp") {}
s.setUserCredentials("scalaprogrammer1#gmail.com", "xxxxxxxx")
val atomFeed = new StdAtomFeed
val f = s.query("http://www.google.com/m8/feeds/contacts/scalaprogrammer1%40gmail.com/base", atomFeed.feedPickler)
for (e <- f) println(e.title)
}
but I am getting this exception :
Exception in thread "main" java.lang.NoSuchMethodError: scala.collection.JavaConversions$.asMap(Ljava/util/Map;)Lscala/collection/mutable/Map;
at com.google.gdata.client.HttpConnection$HttpResponse.headers(HttpConnection.scala:215)
at com.google.gdata.client.ClientLoginFactory.getToken(ClientLoginFactory.scala:104)
at com.google.gdata.client.ClientLoginFactory.setUserCredentials(ClientLoginFactory.scala:59)
at com.google.gdata.Service.setUserCredentials(Service.scala:62)
at Con$delayedInit$body.apply(Con.scala:9)
at scala.Function0$class.apply$mcV$sp(Function0.scala:40)
at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:71)
at scala.App$$anonfun$main$1.apply(App.scala:71)
at scala.collection.immutable.List.foreach(List.scala:318)
at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:32)
at scala.App$class.main(App.scala:71)
at Con$.main(Con.scala:6)
at Con.main(Con.scala)
I am new to scala , can anybody suggest where am i lacking?