trees and external storage level= child= / / level= child= / / level= child= / level= child= / / the output is not very intuitivebut there' enough information to draw the tree if you want the levelstarting with at the rootis shownas well as the child number the display algorithm is depth-firstso the root is shown firstthen its first child and the subtree of which the first child is the rootthen the second child and its subtreeand so on the output shows two items being inserted and the second of these caused node (the root' child to split figure depicts the tree that results from these insertionsfollowing the final press of the key child child figure level child level child sample output of the tree java program the complete tree java program listing shows the complete tree java programincluding all the classes just discussed as with most object-oriented programsit' probably easiest to start by examining the big picture classes first and then work down to the detail-oriented classes in this program this order is tree apptree nodedataitem listing the tree java program /tree java /demonstrates tree /to run this programc>java tree app import java io *///////////////////////////////////////////////////////////////class dataitem