初学者求助一段scala代码，快被它的语法搞疯了。。。多谢！

[飞火流云]

RT,不知道该怎么写了，这个语法比Java 难多了，想模拟一个简单的map查找算法，结果总是报错，

package test

trait PartitionStrategy extends Serializable {
  /** Returns the partition number for a given edge. */
  def getPartition(key: Int): Int
}

   case object MetisPartition extends PartitionStrategy {
      val metisMap =new scala.collection.mutable.HashMap[Int,Int] 
 
      def this(xc:Int) {
    	  this(xc,0)   //这里为什么编译报错?
    	  println("Constructor! ")
    	  mockLoadFile()
      }
      
      def mockLoadFile() {
    	  try {
       var id = 1 ;
       while(id < 10000)
       {
           var partition = 5 ;
           metisMap.put(id, partition)
           id = id +1 
       }
       println("size: " + metisMap.size)
    } catch  {
       case ex: Exception => { // Handle missing file 
            ex.printStackTrace()
       }  
    }
  }
     
    override def getPartition(src: Int): Int = {
      var s = metisMap.get(src.hashCode())
      if(!s.isEmpty)
      return s.getOrElse(0)
      else
        throw new IllegalArgumentException("Metis can't find partition!")
    }
    
     def main(args :Array[String]){
     try {
          val partitionStrategy = new PartitionStrategy  ////这里应该如何定义? 编译不过去
          println(partitionStrategy.getPartition(110))
     } catch {
         case ex: Exception => {
           ex.printStackTrace() 
         }
     } 
   }
  }
   
   

[飞火流云]

RT, 希望实现子类对象的MAp查询， 快被scala的语法搞疯了，过于简洁了，各种不习惯！!!!!!!!!!!

[飞火流云]

或者，定义父类后怎么转化子类对象？　就是Ｊａｖａ中的多态如何实现？

[飞火流云]

简单的说，我的问题是，一个对象继承了 trait后，如果想在该对象初始化的时候进行一些操作，如何编写构造函数？

[yguihojjl]

很好的资源！！！

[m0_37889105]

[

class MetisPartition(x1:Int,x2:Int) extends PartitionStrategy {
  val metisMap =new scala.collection.mutable.HashMap[Int,Int]

  def this(x1:Int) {
    this(x1,0)   //这里为什么编译报错?
    println("Constructor! ")
    mockLoadFile()
  }

  def mockLoadFile() {
    try {
      var id = 1 ;
      while(id < 10000)
      {
        var partition = 5 ;
        metisMap.put(id, partition)
        id = id +1
      }
      println("size: " + metisMap.size)
    } catch  {
      case ex: Exception => { // Handle missing file 
        ex.printStackTrace()
      }
    }
  }

  override def getPartition(src: Int): Int = {
    var s = metisMap.get(src.hashCode())
    if(!s.isEmpty)
      return s.getOrElse(0)
    else
      throw new IllegalArgumentException("Metis can't find partition!")
  }

  def main(args :Array[String]){
    try {
      val partitionStrategy = new MetisPartition(1)  ////这里应该如何定义? 编译不过去
      println(partitionStrategy.getPartition(110))
    } catch {
      case ex: Exception => {
        ex.printStackTrace()
      }
    }
  }
}