如何获得Java二进制搜索树中的每个项目并将其与另一个变量进行比较？

Question

I wrote code for a linked list dvd inventory program that allows me to traverse the list using a for loop and compare each dvd title on the list to the dvd title that was entered by the user. If the title matched, it would then print out the number of copies that are in stock of that title. The code for this is below:

movieToCommand = input.substring(2, input.length()).toLowerCase();

for (int i = 1; i <= movies.length(); i++) {
  if (movies.get(i).getTitle().equals(inputMovie)) {
    System.out.println("There are currently " 
     + movies.get(i).getCopies()
     + " copies of \"" 
     + movies.get(i).getTitle()
     + "\" in stock.");
    }
  }

I am now re-writing the project using a binary search tree. I have gotten the tree to be able to add items, however I cannot figure out how to access each item on the tree and compare it like I did for the linked list. Does anyone know how I can do this?

Thanks

Answer 1

Since you have a binary search tree, and the user is simply entering a movie title, I am assuming that your tree is built based on String . You can keep the movie titles in a TreeMap . A TreeMap is implemented using a Red-Black tree, which is a self-balancing binary search tree.

Maintain a TreeMap (say, allMovies ) with movie titles as keys and the actual movie object (on which you are calling getCopies() ) as values. Therefore, once the user gives a String object (a movie title, say, String aTitle; ), you will simply need to return allMovies.get(aTitle).getCopies() .