Scala实现树形结构

package graphx

import java.util.ArrayList
import java.util.List

/**
  * Created by zhen on 2018/12/28.
  */
object TreeParent {

  class Node {
    var id: String = ""
    var parent: Int = 0

    def this(id: String) {
      this()
      this.id = id
    }

    def this(id: String, parent: Int) {
      this()
      this.id = id
      this.parent = parent
    }

    override def toString: String = {
      return "TreeParent$Node [id=" + id + ", parent=" + parent + "]"
    }
  }
}

class TreeParent {
  private val list : List[TreeParent.Node] = new ArrayList[TreeParent.Node]()
  private var nodeNums: Int = 0

  /**
    * 指定根节点创建树
    */
  def this(id: String) {
    this()
    list.add(new TreeParent.Node(id, -1))
    nodeNums += 1
  }

  /**
    * 指定根节点、指定treeSize创建树
    */
  def this(id: String, treeSize: Int) {
    this()
    list.add(new TreeParent.Node(id, -1))
    nodeNums += 1
  }

  /**
    * 获取某个节点的索引值
    */
  def getNodeIndex(node: TreeParent.Node): Int = {
    for(i<- 0 until list.size())
    {
      if (list.get(i) eq node) {
        return i
      }
    }
    return -1
  }

  /**
    * 为指定节点添加子节点
    */
  def addNode(id: String, parent: TreeParent.Node) {
    list.add(new TreeParent.Node(id, getNodeIndex(parent)))
  }

  /**
    * 判断树是否为空
    */
  def isEmpty: Boolean = {
    return list.get(0) == null
  }

  /**
    * 返回根节点
    */
  def getRoot: TreeParent.Node = {
    return list.get(0)
  }

  /**
    * 返回指定节点(非根节点)的父节点
    */
  def getParent(node: TreeParent.Node): TreeParent.Node = {
    return list.get(node.parent)
  }

  def getNodeByid(id: String): TreeParent.Node = {
    for(i<- 0 until list.size())
    {
      if (list.get(i).id eq id) {
        return list.get(i)
      }
    }
    System.out.println("树中不存在包含该数据的节点")
    return null
  }

  /**
    * 返回指定节点(非叶子节点)的所有子节点
    */
  def getChildren(parent: TreeParent.Node): List[TreeParent.Node] = {
    val childrenList : List[TreeParent.Node] = new ArrayList[TreeParent.Node]()
    for(i <- 0 until list.size()){
      if (list.get(i) != null && list.get(i).parent == getNodeIndex(parent)) {
        childrenList.add(list.get(i))
      }
    }
    return childrenList
  }
}

object TreeAI {
  def main(args: Array[String]) {
    val tree: TreeParent = new TreeParent("root")
    val root: TreeParent.Node = tree.getRoot
    System.out.println(root)
    tree.addNode("A", root)
    tree.addNode("B", root)
    val A: TreeParent.Node = tree.getNodeByid("A")
    val B: TreeParent.Node = tree.getNodeByid("B")
    tree.addNode("C", A)
    tree.addNode("D", A)
    tree.addNode("E", B)
    tree.addNode("F", B)
    tree.addNode("G", B)
    tree.addNode("H", root)
    val H: TreeParent.Node = tree.getNodeByid("H")
    tree.addNode("I", H)
    val list: List[TreeParent.Node] = tree.getChildren(root)
    System.out.println("A节点的子节点为：")
    import scala.collection.JavaConversions._
    for (node <- list) {
      System.out.println(node)
    }
  }
}

结果：