Hello, I need help with my java homework

In this programming assignment, you are asked to implement a nonrecursive inorder traversal algorithm in Java for the binary tree. Figure below provides a good example with explanations. Your solution needs to check if the input is empty and can backtrack from the empty subtree and visit the node at the top of the stack.

The ADT Binary Tree (The notation ?60 means "a reference to the node containing 60 Stack: @gE ??? null 1010 ?201 1-201 1-20 null 20 20020 60 | 60 | Visit 20 ->60 1 ?60 | Visit 10-60 | 10 Step:1 4 20 70 treeNode at Steps 2, 9, and 10 40 treeNode at Steps 3, 5, 6, and 810 treeNode is null at Steps 4 and7 30 50