metrics-scala项目得到了一个建议更改的pull-request: class Meter {
def exceptionMarker: new AnyRef() {
def apply[A](f: => A): A = ???
}
} 致更好的人: class Meter {
object exceptionMarker { // only this line changed
def apply[A](f: => A): A = ???
}
} 但是,我担心这会导致二进制不兼容。我当然和Mima确认过了。米玛并没有抱怨。 所以我的
我试图使用Scala2.10.2执行scala代码,代码使用了一些用sbt编译的jar库。
我得到以下错误:
scala: error while loading Order, class file '..\prestashop-scala-client-0.2.4\target\prestasac-0.2.4.jar(co/orderly/prestasac/representations/Order.class)' is broken
(class java.lang.RuntimeException/Scala class file does not contain Sc
只要我引入一个依赖项(使用SBT),我就会看到有关多个依赖项的警告。
scalaVersion := "2.10.4"
libraryDependencies ++= Seq(
"org.apache.spark" %% "spark-core" % "1.5.0" % "provided"
)
警告:
[warn] Multiple dependencies with the same organization/name but different versions. To avoid con
我的scala解释器/编译器有一个非常奇怪的行为。
Welcome to Scala version 2.10.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_45).
Type in expressions to have them evaluated.
Type :help for more information.
scala> class Foo {
| def bar = {
| println("Foo is bar!")
| }
| }
defined
我已经实现了一个读取端处理器来放置已处理的事件并维护一个读取端cassandra表。但是,发现事件源在一段时间后失败,并出现此错误。
[error] a.a.OneForOneStrategy - com.syn.common.akka.message.drive.CItem; local class incompatible: stream classdesc serialVersionUID = -2252861520543301684, local class serialVersionUID = -3725205170570257368
java.io.InvalidClassExce
我在玩弄Scala的结构类型时,发现了对我来说像是bug的东西。下面是我的代码:
type toD = { def toDouble: Double }
def foo(t: toD) = t.toDouble
foo(5)
我得到了这个错误:
java.lang.NoSuchMethodException
at scala.runtime.BoxesRunTime.toDouble(Unknown Source)
at .foo(<console>:9)
at .<init>(<console>:11)
at .<clinit>(<con
给定类型别名type Cal = java.util.Calendar,如何访问static getInstance方法?我在Scala REPL中尝试了以下操作:
scala> type Cal = java.util.Calendar
defined type alias Cal
scala> Cal.getInstance
<console>:8: error: not found: value Cal
Cal.getInstance
^
scala> val Cal = java.util.Calendar
<
我正在尝试在intellij中为一个基于sbt的Scala应用程序运行测试。但我得到了以下错误,我不确定如何修复:
Testing started at 21:07 ...
java.lang.IncompatibleClassChangeError: Found class scala.collection.mutable.ArrayOps, but interface was expected
at org.scalatest.tools.Runner$.checkArgsForValidity(Runner.scala:895)
at org.scalatest.tool
对于以下构造函数的调用:
class SparkContext(
val master: String,
val appName: String,
val sparkHome: String = null,
val jars: Seq[String] = Nil,
val environment: Map[String, String] = Map())
extends Logging {
在下面的通知中,最后一个参数被注释掉了:
val spark = new SparkContext("localhost", "Group
我正在用Scala2.9.1编译一个项目
java.lang.AssertionError: assertion failed
at scala.Predef$.assert(Predef.scala:89)
at scala.tools.nsc.symtab.Symbols$Symbol.accessed(Symbols.scala:1142)
at scala.tools.nsc.symtab.Symbols$Symbol.accessed(Symbols.scala:1138)
at scala.tools.nsc.transform.Mixin$Mixi
我正在尝试使用Eclipse用Java编写Kafka生产者和消费者代码。我已经下载了Kafka jar文件,并加载为外部Jar文件。解决了依赖问题。
但是,始终存在未解决的错误,消息如下:
Multiple markers at this line
- The type scala.Product cannot be resolved. It is indirectly referenced from required .class files
- The type scala.Serializable cannot be resolved. It is indirectly referenc
似乎copy并不保留原始实例中的任何状态,而只是使用基类定义来创建一个具有新值的新实例。有人知道为什么会这样实现吗?
scala> case class A(){ var y = 2 }
defined class A
scala> val a = new A()
a: A = A()
scala> a.y = 9
a.y: Int = 9
scala> a.y
res9: Int = 9
scala> val b = a.copy()
b: A = A()
scala> b.y
res10: Int = 2
我正在尝试使用激活器和scala play开发简单的web应用程序。但是,当我试图向lib/目录中添加一些外部JAR时,会引发以下异常。即使我没有从里面进口任何东西。
有什么线索吗?我尝试了sbt clean,删除了target/,重新启动了激活器,但是没有什么帮助。
Setting up Play fork run ... (use Ctrl+D to cancel)
Play fork run has failed due to:
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAcces