如何以字符串方法打印树的数据？

Question

I have this method that prints the contents of the Avl tree .

public String traverseInOrder() {
      return traverseInOrder(root);
}

private String traverseInOrder(TNode<T> node) {
  String Str = "";
    if (node != null) {
      if (node.left != null)
        traverseInOrder(node.left);
        Str +=node;
      if (node.right != null)
        traverseInOrder(node.right);
    }
  return Str;
} 

There will still be a problem that in this case you are returning one node of the Avl tree and I need all the node in the Avl tree. I don't want to use some kind of void method

Answer 1

You need to add the result of the recursion to Str . like so: Str += traversInOrder(node.left) and the same goes for the right one. You also should print the content of the node with node.value or whatever your content value name is.

Example:

private String traverseInOrder(TNode<T> node) {
  String Str = "";
    if (node != null) {
      if (node.left != null)
        Str += traverseInOrder(node.left);
      Str += node.value;
      if (node.right != null)
        Str += traverseInOrder(node.right);
    }
  return Str;
} 

Answer 2

public String traverseInOrder() {       
    return traverseInOrder(root);
}
private String traverseInOrder(TNode<T> node) {
     String Str = "";
     if (node != null) {
            if (node.left != null)
                Str+=traverseInOrder(node.left);
            Str+=node;          
            if (node.right != null)
                Str+=traverseInOrder(node.right);
    }
    return Str;
}