/********************************************************************* * Author: B. Alex Bridges * * Login ID: brid0129 * * Class: CPSC-102, Summer 1998 * * Project: Programming Assignment 4 * * Description: This program is a simple database query system for a * * video store. * * Contents: Methods for dealing with Video objects. * *********************************************************************/ /* IMPORTS */ import java.io.*; class Videos { /* CONSTANTS */ final static boolean b_debug = false; // CONTROLS EXTRA DEBUG OUTPUT final static String str_default = ""; // DEFAULT STRING VALUE final static int int_default = -1; // DEFAULT INTEGER VALUE /* OBJECT VARIABLES */ private Video Video_root; // VIDEO OBJECT FOR POINTER TO ROOT NODE // OF IN-STOCK B.S.T. // (OR NULL FOR EMPTY TREE) /************************************************************************* * Method: get_movie * * Purpose: Gets the movie properties--title, release year, runtime, * * and availabilty. * * Input: --PARAMATERS-- * * => 'br_file_in' = The BufferedReader for the video database. * * Output: --RETURNS-- * * => SUCCESS = The movie. * * => FAILURE = null * *************************************************************************/ public static Video get_movie(BufferedReader br_file_in) { /* LOCAL VARIABLES */ Video Video_read = new Video(); // VIDEO OBJECT FOR READ MOVIE /* READING OF MOVIE PROPERTIES */ try { Video_read.str_title = br_file_in.readLine(); Video_read.int_year = Integer.parseInt( br_file_in.readLine() ); Video_read.int_runtime = Integer.parseInt( br_file_in.readLine() ); Video_read.str_available = br_file_in.readLine(); Video_read.Video_left = null; Video_read.Video_right = null; return Video_read; } // try /* EXCEPTION HANDLING */ catch(IOException exception) { System.out.println(" FATAL EXCEPTION: File input problem."); return null; } // catch } // method get_movie /************************************************************************* * Method: print_movies * * Purpose: Calls the private method print_movies_r. * * Input: none * * Output: none * *************************************************************************/ public void print_movies() { print_movies_r(Video_root); } // method print_movies /************************************************************************* * Method: print_movies_r * * Purpose: Recursively prints a binary search tree of movies. * * Input: --PARAMATERS-- * * => 'Video_tree'= The B.S.T. of movies. * * Output: none * *************************************************************************/ private static void print_movies_r(Video Video_tree) { /* NON-EMPTY NODE */ if(Video_tree != null) { print_movies_r(Video_tree.Video_left); print_movie(Video_tree); print_movies_r(Video_tree.Video_right); } // if } // method print_movies_r /************************************************************************* * Method: print_movie * * Purpose: Prints a movie's properties--title, release year, runtime, * * and availabilty. * * => 'Video_print'= The movie which is to be printed. * * Output: none * *************************************************************************/ public static void print_movie(Video Video_print) { /* PRINTING OF MOVIE PROPERTIES */ System.out.print("Title: "+Video_print.str_title+"\n"+ "Released: "+Video_print.int_year+"\n"+ "Runtime: "+Video_print.int_runtime+" minutes\n"); if( Video_print.str_available.equals("false") ) System.out.println("Available: No\n"); else if( Video_print.str_available.equals("true") ) System.out.println("Available: Yes\n"); else System.out.println(" ERROR: Availability of '"+Video_print.str_available+"' is invalid. Must be 'true' or 'false'.\n"); } // method print_movie /************************************************************************* * Method: write_movies * * Purpose: Calls the private method write_movies_r. * * Input: --PARAMATERS-- * * => 'bw_file_out' = The original B.W. for the video database. * * Output: --RETURNS-- * * => 'bw_file_out' = The updated B.W. for the video database. * *************************************************************************/ public BufferedWriter write_movies(BufferedWriter bw_file_out) { return( write_movies_r(bw_file_out, Video_root) ); } // method write_movies /************************************************************************* * Method: write_movies_r * * Purpose: Recursively writes a binary search tree of movies. * * Input: --PARAMATERS-- * * => 'bw_file_out' = The original B.W. for the video database. * * => 'Video_tree' = The B.S.T. of movies. * * Output: --RETURNS-- * * => 'bw_file_out' = The updated B.W. for the video database. * *************************************************************************/ private static BufferedWriter write_movies_r(BufferedWriter bw_file_out, Video Video_tree) { /* NON-EMPTY NODE */ if(Video_tree != null) { bw_file_out = write_movies_r(bw_file_out, Video_tree.Video_left); bw_file_out = write_movie(bw_file_out, Video_tree); bw_file_out = write_movies_r(bw_file_out, Video_tree.Video_right); return bw_file_out; } // if /* EMPTY NODE */ return bw_file_out; } // method write_movies_r /************************************************************************* * Method: write_movie * * Purpose: Writes a movie's properties--title, release year, runtime, * * and availabilty. * * Input: --PARAMATERS-- * * => 'bw_file_out' = The original. B.W. for the video database. * * => 'Video_write' = The movie which is to be written. * * Output: --RETURNS-- * * => 'bw_file_out' = The updated B.W. for the video database. * *************************************************************************/ public static BufferedWriter write_movie(BufferedWriter bw_file_out, Video Video_write) { try { /* WRITING OF MOVIE PROPERTIES */ bw_file_out.write(Video_write.str_title); bw_file_out.newLine(); bw_file_out.write( String.valueOf(Video_write.int_year) ); bw_file_out.newLine(); bw_file_out.write( String.valueOf(Video_write.int_runtime) ); bw_file_out.newLine(); bw_file_out.write(Video_write.str_available); bw_file_out.newLine(); return bw_file_out; } // try catch(IOException exception) { System.out.println(" EXCEPTION: File output problem."); return null; } // catch } // method write_movie /************************************************************************* * Method: insert_movie * * Purpose: Calls the private method insert_movie_r. * * Input: --PARAMATERS-- * * => 'Video_insert' = The movie which is to be inserted. * * Output: none * *************************************************************************/ public void insert_movie(Video Video_insert) { Video_root = insert_movie_r(Video_root, Video_insert); } // method insert_movie /************************************************************************* * Method: insert_movie_r * * Purpose: Recursively inserts movie into the binary search tree--keep- * * ing the ascending order by title. * * Input: --PARAMATERS-- * * => 'Video_tree' = The B.S.T. of movies. * * => 'Video_insert' = The movie which is to be inserted. * * Output: --RETURNS-- * * => 'Video_tree' = The new B.S.T. of movies. * *************************************************************************/ private Video insert_movie_r(Video Video_tree, Video Video_insert) { /* EMPTY NODE */ if(Video_tree == null) return Video_insert; /* INSERT < CURRENT NODE */ else if( Video_insert.str_title.compareTo(Video_tree.str_title) < 0 ) { Video_tree.Video_left = insert_movie_r(Video_tree.Video_left, Video_insert); return Video_tree; } // if /* INSERT > CURRENT NODE */ else { Video_tree.Video_right = insert_movie_r(Video_tree.Video_right, Video_insert); return Video_tree; } // else } // method insert_movie_r /************************************************************************* * Method: delete_movie * * Purpose: Calls the private method delete_movie_r. * * Input: --PARAMATERS-- * * => 'str_del' = The title for which to delete. * * Output: none * *************************************************************************/ public void delete_movie(String str_delete) { Video_root = delete_movie_r(Video_root, str_delete); } // method insert_movie /************************************************************************* * Method: delete_movie_r * * Purpose: Recursively deletes movie from the binary search tree. * * Input: --PARAMATERS-- * * => 'Video_tree' = The B.S.T. of movies. * * => 'str_del' = The title for which to delete. * * Output: --RETURNS-- * * => 'Video_tree' = The new B.S.T. of movies. * *************************************************************************/ public static Video delete_movie_r(Video Video_tree, String str_del) { /* EMPTY NODE */ if(Video_tree == null) return null; /* NON-EMPTY NODE */ // => LESS THAN --> TRAVERSE LEFT if( str_del.compareTo(Video_tree.str_title) < 0 ) { Video_tree.Video_left = delete_movie_r(Video_tree.Video_left, str_del); return Video_tree; } // if // => GREATER THAN --> TRAVERSE RIGHT else if( str_del.compareTo(Video_tree.str_title) > 0 ) { Video_tree.Video_right = delete_movie_r(Video_tree.Video_right, str_del); return Video_tree; } // if // => EQUAL --> DELETE else { if( (Video_tree.Video_left == null) && (Video_tree.Video_right == null) ) return null; else if( Video_tree.Video_left == null) return Video_tree.Video_right; else if( Video_tree.Video_right == null) return Video_tree.Video_left; else { Video Video_swap = Video_tree.Video_right; while(Video_swap.Video_left != null) Video_swap = Video_swap.Video_left; // => TRANSFER DATUMS Video_tree.str_title = Video_swap.str_title; Video_tree.int_year = Video_swap.int_year; Video_tree.int_runtime = Video_swap.int_runtime; Video_tree.str_available = Video_swap.str_available; Video_tree.Video_right = delete_movie_r(Video_tree.Video_right, Video_swap.str_title); return Video_tree; } // else } // else } // method delete_movie_r /************************************************************************* * Method: find_movie * * Purpose: Calls the private method find_movie_r. * * Input: --PARAMATERS-- * * => 'str_search' = The title for which to search. * * Output: --RETURNS-- * * => SUCCESS = The matching movie along with the remaining B.S.T.* * => FAILURE = null * *************************************************************************/ public Video find_movie(String str_search) { return( find_movie_r(Video_root, str_search) ); } // method find_movie /************************************************************************* * Method: find_movie_r * * Purpose: Searches for movie in the linked list with matching title. * * Input: --PARAMATERS-- * * => 'Video_tree' = The B.S.T. of movies. * * => 'str_search' = The title for which to search. * * Output: --RETURNS-- * * => SUCCESS = The matching movie with the remaining linked list.* * => FAILURE = null * *************************************************************************/ private static Video find_movie_r(Video Video_tree, String str_search) { /* EMPTY NODE */ if(Video_tree == null) return Video_tree; /* NON-EMPTY NODE */ // => EQUAL --> STOP if( str_search.compareTo(Video_tree.str_title) == 0) return Video_tree; // => LESS THAN --> TRAVERSE LEFT if( str_search.compareTo(Video_tree.str_title) < 0) return find_movie_r(Video_tree.Video_left, str_search); // => GREATER THAN --> TRAVERSE RIGHT else return find_movie_r(Video_tree.Video_right, str_search); } // method find_movie_r } // class Videos