小编Sud*_*Deb的帖子

以下是我尝试运行的代码:

class Student {
  def printDetails = println("I am a student")
  def printSomeOtherDetails = println("I love Studying")
}

class ComputerScienceStudent extends Student {
  override def printDetails = println("I am a Computer Science Student")
  override def printSomeOtherDetails = println("I love Scala")
}

class InformationTechnologyStudent extends Student {
  override def printDetails = println("I am an Information Technology Student")
  override def printSomeOtherDetails = println("I love Java")
}

class MyGenericClassForUpperBound {
  def printStudentDetails[S <: Student](student: S) = {
    student.printDetails
    student.printSomeOtherDetails
  }
}

class MyGenericClassforLowerBound …

在我的支持bean中,如果我有一个列表,那么我可以使用

rendered="#{not empty name}" or rendered="#{not null name}"

对？但如果我只有实例变量(不是列表),那么我可以使用

rendered="#{not empty name}" ?

我对Scala中的QuickSort很困惑.根据规范,QuickSort只能应用于Array,但不能应用于ArrayBuffer.并且QuickSort将在场中进行排序,即将更改原始阵列.

val intArray = Array(7,1,4,6,9)           //> intArray  : Array[Int] = Array(7, 1, 4, 6, 9)
Sorting.quickSort(intArray)
intArray.mkString("<"," and ",">")        //> res4: String = <1 and 4 and 6 and 7 and 9>

现在我无法理解为什么我不能用ArrayBuilder做同样的事情.这背后有什么理由吗？如果我想用QuickSort算法对ArrayBuilder进行排序,那么scala提供的选项是什么？谢谢你的帮助.

我试图理解Scala中的Anonymous子类.我写了下面的代码:

package com.sudipta.practice.chapter8

class Person(val name: String) {
  def printMyName = println("Name: " + name)
}

class AnonymousSubclass(val name: String) {
    val anonymousSubclass = new Person(name){
      def sayHello = "Hello, " + name
      def sayBye = "Bye, " + name
      override def printMyName = println("My name is: " + name)
    }

}

object testPerson extends App {

  def printAnonDetails (myObject: AnonymousSubclass) = {
    myObject.anonymousSubclass.printMyName
  }

  val personObject = new Person("Sudipta")
  personObject.printMyName

  val anonObject = new AnonymousSubclass("Sudipta")

  printAnonDetails(anonObject)
}

但是我无法理解Scala中Anonymous Subclass的用法/优点是什么.如果您有任何积分,请在此处分享.谢谢. …

我在尝试从Eclipse执行以下代码时遇到错误,因为我无法重新分配Val,对吧？

object Test {
    def main(args: Array[String]){
      val tempVal = 100;

      val checkval = if (tempVal > 50) 1 else 0

      println("The new value is: " + checkval);

      //Getting Error Below
      checkval1 = if (tempVal > 200) 0

    }
}

现在,当我尝试从命令行执行相同的操作时,为什么我没有得到相同的错误？

在PrimeFaces中,我们可以在复选框的帮助下从下拉列表中选择多个元素吗？如果我的下拉列表显示5个元素,我可以从列表中选择多个元素吗？

我知道在primeFaces中我们可以<p:selectOneMenu>选择一个元素,但是我们有类似的东西<p:selectMultipleMenu>吗？

我试图找到它但却找不到东西.能告诉我这是否可行吗？

以下是我的代码片段:

sealed abstract class Expr
case class Var(name: String) extends Expr
case class Number(num: Double) extends Expr
case class UnOp(operator: String, arg: Expr) extends Expr
case class BinOp(operator: String, left: Expr, right: Expr) extends Expr

object CaseClassTest extends App {
    def simplifyExp(xs: Expr): Expr = xs match {
      case UnOp("-",UnOp("-", x)) => x
      case BinOp("+",x,Number(0)) => x
      case BinOp("*",x,Number(1)) => x
    }

    def describe(e: Expr): String = e match {
      case Number(_) => "Number"
      case Var(_) => "Var"
    } 
} …