java - 带有字符串数据的二叉树的预排序序列

Question

class TreeNode {
  String value;
  TreeNode left;
  TreeNode right;

  public TreeNode(String value){ //constructs a leaf
    this.value = value;
    right = null;
    left = null;
  }

  public TreeNode(String value, TreeNode left, TreeNode right){
    this.value = value;
    this.left = left;
    this.right = right;
  }//makes treenode with left and right children
  public TreeNode getLeft(){
    return this.left;
  }
  public TreeNode getRight(){
    return this.right;
  }
  public boolean isLeaf(){
    if (this.right == null && this.left == null){
      return true;
    }
    else{
      return false;
    }
  }
}




class Main{

  public static TreeNode maketree(){
   //create Binary Tree with traversal
  }

  public static void main(String[] args){
    String Classical = "Do you like classical music?";
    String Mozart = "Are you a fan of Mozart?";
    String TakeFive = "\"Take Five\" by Dave Brubeck.";
    String EineKleine = "Eine Kleine Nachtmusik.";
    String ThreeRomances = "\"3 Romances\" by Clara Schumann.";
    String[] pre = {Classical, Mozart, EineKleine, ThreeRomances, TakeFive};
  }
}

数组 pre 已经在 pre order 我希望将它转换回二叉树任何带有“？”的字符串 是一个以经典为根的节点，任何带有 '.' 的节点。是一片叶子。我发现很多整数，但我看不到字符串。