Movie Binary Search Tree 🍿

The program, written in java, reads in a text file with movies and creates a binary search tree. The program can search for movies with the exact title, traverse the tree in order, and search for movies beginning with specific characters. All functions were written recursively. The movies are inserted in the tree in lexicographic order by the short names of the movies.

Instructions

Download BSTIndex.java, IndexTester.java, MovieInfo.java, and data.zip files. Unzip the data.zip file and it should contain many different files each containing a different number of movies and their information. To run, IndexTester.java takes command line arguments for file containing movie information ($ java IndexTest data/filename.txt).

Example

$ java IndexTester.java data/movies100.txt
Index building complete. Inserted 99 records. Elapsed time = 0 seconds.

Welcome to the IMDB movie search engine!
- Enter search string to find a specific movie. 
- Enter search string ending with '*' to print all movies that match this prefix. 
- Enter 'h' to print tree height. 
- Enter 'q' to quit.
Enter Option: Plan 10 from Outer Space
100011 Plan 10 from Outer Space Plan 10 from Outer Space
Enter Option: Ta*
[Finding all movies that start with Ta..]
Tange Sazen: zankoku no kawa
Takekurabe
Tamaru onna
Enter Option: h
Height of BSTIndex tree = 19
Enter Option: q

Breakdown

Classes

• BSTIndex.java: BST class that contains an inner node with that takes a parameter of type MovieInfo and holds a movie's short-hand title in key and the rest of the movie information (see MovieInfo.java). The class contains public methods which call private methods where the implementation of the methods are.
  • private int calcNodeHeight(Node t): recursively calculates the height of the tree, called by inputing h in the menu when prompted to Enter Option:
  • private Node insertMovie(MovieInfo data, Node t): recursively determines a position to correctly insert the movie and its data into the binary search tree. Again, the movies are inserted in lexicographic order by the shortTitle of the movie. Called everytime a BST is created/$ java IndexTester.java data/movies100.txt.
  • private MovieInfo findMovie(Node t, String key): recursively searches the tree for a movie with a matching key or movie shortTitle. Returns null if the key is not found in any of the nodes in the tree. This function is called by typing in a string into the menu when prompted to Enter Option:
  • private void getMoviesPrefix(Node t, String prefix, ArrayList<String> movieList): recursively searches the tree for a movie shortTitle starting with prefix and adds shortTitle to an array list movieList. This function is called by typing in a string followed by a * into the menu when prompted to Enter Option:
  • private void inorderTraversal(Node t, ArrayList<Integer> movieList): recursively traverses BST inorder.
• IndexTester.java: checks if command line argument for a filename.txt is passed or it throws an error, loads in filename.txt and inserts each line into a BST, and displays the menu in the console allowing for multiple selections.
• MovieInfo.java: MovieInfo class that stores a movie's ID, shortTitle, and fullTitle.

Data

data.zip must be unzipped before using and contains text files that hold different amounts of movie data. These files can be used when calling IndexTester.java data/filename.txt. Each movie contains an ID, shortTitle, and fullTitle separated by spaces (10 Ocean's 7-11 Ocean's 7-11 (2008)).

Filename	# of movies
movies.txt	500,000
movies1.txt	1
movies10.txt	10
movies100.txt	100
movies100k.txt	100,000

Challenges

This was my first time using BST and to do it recursively was definitely a challenge. Although I was initially pretty shakey on my recursion, after lots of practice problems online I was able to apply what I had learned to create recursive function.