自定义Java字母序二叉搜索树类未正常工作，寻求技术解决方案

Hey there! I’ve dealt with my fair share of wonky custom tree implementations for coursework, so let’s walk through why your BST isn’t matching the ~300 results you get with TreeSet when searching by username. Here are the key areas to investigate:

1. Verify Your User Class Comparison Logic #

TreeSet relies entirely on either the Comparable interface implementation in your User class or a custom Comparator you pass in. If your BST doesn’t use exactly the same comparison rules as TreeSet, your sorting and search results will diverge:

• Double-check that your compareTo method only considers the username field (since you’re sorting/searching by username):

  @Override
  public int compareTo(User other) {
      // Match TreeSet's behavior—if TreeSet uses case-insensitive comparison, use compareToIgnoreCase here
      return this.username.compareTo(other.username);
  }
  

• Also, note that TreeSet treats two User objects as identical if compareTo returns 0 (even if their passwords differ). If your BST allows duplicate username entries (while TreeSet deduplicates them), your result counts will never align.

2. Audit Your BST Insert Logic #

Custom BSTs are prone to silly insertion bugs that silently drop or misplace elements. To debug this:

• Perform an in-order traversal of your BST and compare the output to TreeSet’s ordered iteration. In-order traversal of a valid BST should produce the exact same sequence as a TreeSet (since both are sorted). If elements are missing or out of order, your insertion logic has a flaw (e.g., swapping left/right traversal when comparing usernames).
• Print the size of both your BST and the TreeSet after loading all users. If your BST’s size is smaller than TreeSet’s, you’re losing elements during insertion.

3. Check Your Search Method Implementation #

If insertion looks solid, your search logic might be cutting corners:

• Ensure your search method doesn’t terminate early when it finds a matching username. If your BST allows duplicate usernames (or if you’re handling edge cases where multiple nodes share the same username), you need to traverse both left and right subtrees after finding a match to collect all results.
• Double-check that your comparison logic during search matches what you use during insertion. For example, if you used compareToIgnoreCase when inserting but compareTo during search, you’ll miss case-variant matches.

4. Confirm Consistent Input Handling #

Make sure both your BST and TreeSet are processing the exact same input data from the text file:

• Check for differences in how you read the file: are you skipping empty lines differently? Handling encoding edge cases? Trimming whitespace from usernames in one implementation but not the other?
• A quick test: load all users into a list first, then add the entire list to both your BST and TreeSet. This eliminates any file-reading inconsistencies as a variable.

5. Test Edge Cases #

Don’t overlook edge cases that might break your BST but work fine in TreeSet:

• Test usernames with special characters, empty strings, or mixed capitalization.
• Test inserting multiple users with identical usernames (TreeSet will deduplicate them—does your BST do the same, or does it allow duplicates? Make sure this aligns with your assignment requirements).

Start with verifying the comparison logic and in-order traversal results—those are the most common culprits for this kind of issue. Good luck with your coursework!

内容的提问来源于stack exchange，提问作者Connor Hobson