Bug 269

Summary:	[SearchEngine] java.lang.NumberFormatException thrown when searching movie
Product:	MovieXXX	Reporter:	tomfong521
Component:	MovieAnalysisEngine	Assignee:	clwong274-c
Status:	RESOLVED FIXED
Severity:	blocker
Priority:	High
Version:	1.0
Hardware:	PC
OS:	Windows
Deadline:	2018-11-17

Description tomfong521 2018-11-29 22:39:46 HKT

Details:
After enter keyword to filter recommendation, an java.lang.NumberFormatException is thrown

Reproducible steps
1. Enter "2" to select "Film Recommendation" in [System Home]
2. Enter "1" to select "Start New Recommendation" in [Office Box Prediction]
3. Enter keyword (e.g. "german") to process recommendation

Expected results:
- At step (3), no exception or error should be shown, recommendation can be performed and printed successfully. 

Actual results:
- At step (3), java.lang.NumberFormatException is thrown and the program is interrupted

Detailed console output:
 >> Enter any keyword to filter your customised recommendation: 
 >> german
 >> Exception in thread "main" java.lang.NumberFormatException: For input string: ""
 >> 	at java.lang.NumberFormatException.forInputString(Unknown Source)
 >> 	at java.lang.Integer.parseInt(Unknown Source)
 >> 	at java.lang.Integer.parseInt(Unknown Source)
 >> 	at movieRating.SearchEngine.searchMovie(SearchEngine.java:31)
 >> 	at movieRating.RecommendSys.doNewRecommendation(RecommendSys.java:21)
 >> 	at movieRating.RecommendSys.enter(RecommendSys.java:47)
 >> 	at movieRating.Main.main(Main.java:28)

Comment 1 clwong274-c 2018-11-30 00:05:54 HKT

Root cause
- There are empty data cells in the database, when these data are read as string and being phrased into other type (e.g. integer in SearchEngine.java:31) format exception will be thrown

How to fix
- Added to check if the read data is empty string before phrasing, pass "" instead if so

Expected behavior
- No exception or error should be shown, recommendation can be performed and printed successfully

Potential affected areas
- SearchEngine

Affected versions
- >=v2

Test cases
1. Edit a test database with four movies in it. Enter movie info to satisfy following (e.g. given search parameter "german"):
   MovieA: movie_title="1984" title_year="2018" language="english"
   MovieB: movie_title="Hello world" title_year=""(empty) language="german"
2. Enter "2" to select "Film Recommendation" in [System Home]
3. Enter "1" to select "Start New Recommendation" in [Office Box Prediction]
4. Enter keyword (e.g. "german") to process recommendation


Test result
- At step (4), no exception or error is shown, recommendation is performed and printed successfully
- Movie row in database with empty data can be used to construct a Film class object
- Printed output: MovieB