这是没有问题的编译: override def toStringTweet = elem if (cur.retweets > max.retweets) max=curforeach(most( _ ))Error:(157, 19) missing parameter type for expande 浏览25提问于2017-01-20得票数1 回答已采纳 3回答 发现Scala类型不匹配的单位:必需的Array[Int] ...
someNumbers.foreach(println) 最后一种格式仅在需要写函数的地方,如例子中的foreach调用,才能使用。编译器知道这种情况需要一个函数,因为foreach需要一个函数作为参数传入。在不需要函数的情况下,尝试使用这种格式将引发一个编译错误。举例如下: scala> val c = sum <console>:5: error: missing arguments for me...
scala> l2.fold((x,y) => x-y)<console>:19: error: missing parameter type l2.fold((x,y)=> x-y)^ <console>:19: error: missing parameter type l2.fold((x,y)=> x-y)^ <console>:19: error: missing argument listformethod fold in trait TraversableOnce Unapplied methods are only c...
// ERROR: missing parameter type for expanded function myStrings.foreach(println(_.toString)) It expands to: myStrings.foreach(println(x => x.toString)) You want: myStrings.foreach(x => println(x.toString)) The placeholder syntax for anonymous functions replaces the smallest possible contain...
) missing parameter type for expanded function ((x$1) => x$1.retweets.$greater(max.retweets)) foreach( if ( _.retweets > max.retweets) max=_ ) Error:(157, 14) type mismatch; found : Unit required: objsets.Tweet => Unit foreach( if...
and value foo in object $iw of type => java.lang.String match expected type String 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 系统找到两个隐式参数是相同的类型,将无法识别。 子类可以匹配, scala> def sayThings (implicit args : List[Any]) = args.foreach(println(_)...
scala> numbers.foreach(println(_*2)) <console>:16: error: missing parameter type for expanded function ((x$1) => x$1.$times(2)) numbers.foreach(println(_*2)) 报错原因: println不是一个高阶函数,不能接收一个函数作为参数 (*)filter:过滤,选择满足的数据 ...
(Foo,1) scala> val with2: String With Int = With("Bar", 2) with2: With[String,Int] = With(Bar,2) scala> Seq(with1, with2) foreach { w => | w match { | case s With i => println(s"$s with $i") | case _ => println(s"Unknown: $w") | } | } Foo with 1 ...
Type in expressions for evaluation. Or try :help. scala> val it = Iterator(1,2,3) it: Iterator[Int] = non-empty iterator scala> it foreach println 1 2 3 scala> it foreach println scala> it.toArray res2: Array[Int] = Array() ...
both value bar in object $iw of type => java.lang.String and value foo in object $iw of type => java.lang.String match expected type String 系统找到两个隐式参数是相同的类型,将无法识别。 子类可以匹配, scala> def sayThings (implicit args : List[Any]) = args.foreach(println(_)) ...