AVL树在JTextArea中遍历

Question

public class AVLTree
{
   public static String inorderTraversal = " ";

   private static void inorder(AVLNode btree)
    {
       if (btree != null)
       {
         inorder(btree.left);
         inorderTraversal += btree.value + " ";
         inorder(btree.right);
       }
    } 

    /**
       This inorder method is the public interface to
       the private inorder method. It calls the private 
       inorder method and passes it the root of the tree.
    */

    public static void inorder()
    {
        inorder(root);
    }
}

class AVLTreeDemo extends JFrame
implements ActionListener
{

    public void actionPerformed(ActionEvent evt)
    {
        String cmdStr = cmdTextField.getText();
          int size = Integer.parseInt(cmdStr);
        int[] array = new int[size];

        // input validation


        // Random number method
          randNum(array, size);

        // for loop adds numbers to AVL Tree        
        for (int i = 0; i < size; i++)
        {
            int value = array[i];
            avlTree.add(value);
        }
          if (view != null)
                remove(view);
            view = avlTree.getView();            
            add(view);
            pack();
            validate(); 
            cmdResultTextField.setText(" ");

        // inorder method
        AVLTree.inorder();

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < size; i++)
        {
            sb.append(String.format(" %2d", size)); // Formats right justified
            if ((i + 1) % 10 == 0)
            {
                sb.append(System.lineSeparator()); // Adds a new line after 10 values
            }
        }
        //inorderTextArea.setText(sb.toString(AVLTree.inorderTraversal));

        // display the array in inorder to the inorder text field
        inorderTextArea.setText(AVLTree.inorderTraversal);
    } 

    /**
      The randNum method randomly selects numbers
      in a given range.
      @param array The array.
      @param num The integer numbers.
   */

     public static void randNum(int[] array, int num)
     {                
        Random rand = new Random();

        // Selection sort method
          selectionSort(array);

        // display duplicates
        /*int last = array[0];
        int count = -1;

        for (int i : array)
        {
            if (i == last)
            {
               count++;
               continue;
            }
            System.out.println("Number " + last + " found " + count + " times.");
            count = 1;
            last = i;
         }*/

        for(int i = 0; i < num; i++)
        {
           // display duplicates
           /*if(num == num - 1)
           {
               System.out.print("Duplicate: " + num);
           }*/

           array[i] = rand.nextInt(500);
        }        
    }

    public static void main(String [ ] args)
    {
       AVLTreeDemo atd = new AVLTreeDemo();
    }
}

我正在尝试在JTextArea中的多行上显示AVL树的顺序，预订和后序遍历的输出，最好是10行到一行。我尝试了我提供的'for'循环，但是我遇到了编译错误。问题出在inorderTextArea.setText(sb.toString(AVLTree.inorderTraversal));。

错误：

  

AVLTree.java:527：错误：没有为toString（String）找到合适的方法inorderTextArea.setText（sb.toString（AVLTree.inorderTraversal））; ^方法StringBuilder.toString（）不适用（实际和形式参数列表长度不同）方法AbstractStringBuilder.toString（）不适用（实际和形式参数列表长度不同）方法Object.toString（）不适用（实际和形式参数列表的长度不同）1错误

如何重新编写这行代码才能使其正常工作？谢谢你的帮助。