java - AVL Tree traversals in JTextArea -

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);        }     }       /**        inorder method public interface        private inorder method. calls private         inorder method , passes root of 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);          // loop adds numbers avl tree                 (int = 0; < 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();          (int = 0; < size; i++)         {             sb.append(string.format(" %2d", size)); // formats right justified             if ((i + 1) % 10 == 0)             {                 sb.append(system.lineseparator()); // adds new line after 10 values             }         }         //inordertextarea.settext(sb.tostring(avltree.inordertraversal));          // display array in inorder inorder text field         inordertextarea.settext(avltree.inordertraversal);     }       /**       randnum method randomly selects numbers       in given range.       @param array array.       @param num 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;          (int : array)         {             if (i == last)             {                count++;                continue;             }             system.out.println("number " + last + " found " + count + " times.");             count = 1;             last = i;          }*/          for(int = 0; < 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();     } } 

i'm trying display output of avl tree inorder, preorder, , postorder traversals on multiple lines in jtextarea, preferably 10 numbers line. tried 'for' loop i've provided, i'm getting compile error. problem inordertextarea.settext(sb.tostring(avltree.inordertraversal));.

error:

avltree.java:527: error: no suitable method found tostring(string) inordertextarea.settext(sb.tostring(avltree.inordertraversal)); ^ method stringbuilder.tostring() not applicable (actual , formal argument lists differ in length) method abstractstringbuilder.tostring() not applicable (actual , formal argument lists differ in length) method object.tostring() not applicable (actual , formal argument lists differ in length) 1 error

how can re-write line of code make work? thank help.