Description

Files to submit to Web-CAT (test files are optional):
From Database – Part 1
• DB.java
• CentralizedDB.java, CentralizedDBTest.java
• DistributedDB.java, DistributedDBTest.java
• HomogeneousDB.java, HomogeneousDBTest.java
• HeterogeneousDB.java HeterogeneousDBTest.java

From in Database – Part 2
• MonthlyCostComparator.java, MonthlyCostComparatorTest.java
• DBList.java (add exception handling), DBListTest.java

New in Database – Part 3
• DBPart3.java (with exception handling), DBPart3Test.java
• InvalidCategoryException

Recommendations
You should create new folder for Part 3 and copy your relevant Part 2 source and optional test files to it. You should create a jGRASP project and add the new source and any new optional test files as they are created.

Specifications – Use arrays in this project; ArrayLists are not allowed!

• DB, CentralizedDB, DistributedDB, HomogeneousDB, and HeterogeneousDB

Requirements and Design: There are no changes to these classes from Part 2.

• DBList.java

Requirements: The DBList class provides methods for reading in the data file and generating the reports. The readFile method should redesigned to handle exceptions in the data. Reading a “good” line of data results in a new element being added to the DB array, and reading a “bad” line of data results in the line + an exception message being added the to the invalid records String array. A new report method produces the Invalid Records Report.

Design: The readFile method from Part 2 should be redesigned to handle exceptions. The DBList class has fields, a constructor, and methods as outlined below.
(1) Fields: no change from Part 2.
(2) Constructor: no change from Part 2.
(3) Methods: The readFile method needs to be reworked and the generateInvalidRecordsReport method needs to be added. See Part 2 for the full description of other methods in this class.
o readFile has no return value, accepts the data file name as a String, and throws FileNotFoundException. If a FileNotFoundException occurs when attempting to open the data file, it should be ignored in this method so that it can be handled in the calling method (i.e., main). If a line from the file is processed successfully, a DB object of the appropriate category (subclass) is added to the DB array in the class. However, when an exception occurs as a result from erroneous data in a line read from the file, it should be caught and handled as follows. The line should be concatenated with a newline and the exception message and then the resulting String should be added to the invalid records String array in the class. The three exceptions that should be caught in this method are (1) InvalidCategoryException (described below), (2) NumberFormatException, and (3) NoSuchElementException. Note that the InvalidCategoryException must be explicitly thrown by your code if the category is not C, D, H, or E (hint: in the default case). The NumberFormatException will be thrown automatically if the item scanned in the line from the file is not a double when Double.parseDouble expects it to be a double. The NoSuchElementException will be thrown automatically if the item scanned does not exist (i.e., data is missing). For examples, see the output below for the Invalid Records Report.
o generateInvalidRecordsReport processes the invalid records array to produce the Invalid Records Report and then returns the report as String. See the example result near the end of the output for DBPart3 that begins on page 4 and ends on page 6.
Code and Test: See examples of exception handling in the text and the class notes. In the catch blocks for the NumberFormatException and NoSuchElementException, the invalid line should be concatenated with a newline and the exception message, and the resulting String should be added to the invalidRecords String array. Note that for the NoSuchElementException, “: For missing input data” will need to be concatenated to the end of the toString value of the NoSuchElementException to form the complete message.

Download database_data_2_exceptions.csv from the assignment page in Canvas to test your program. Your optional JUnit test methods should force the exceptions described above to thrown and caught. Since the readFile method will propagate the FileNotFoundException if the file is not found when the Scanner is created to read the file, test method could catch this exception to check that it was thrown. Any other test method involving the readFile method must have the throws FileNotFoundException clause.

InvalidCategoryException.java

Requirements and Design: The InvalidCategoryException class defines a new subclass of the Exception class. The constructor accepts a String categoryIn representing the invalid category, then invokes the super constructor with the message:
“For category: ” + categoryIn
See examples of creating user defined exceptions in text and class notes.

DBPart3.java

Requirements: The DBPart3 class contains the main method for running the program. In addition to the specifications in Part 2, the main method should be modified as indicated below.

Design: The DBPart3 class is the driver class and has a main method described below.

o main accepts a file name as a command line argument, then within a try block, creates a DBList object, and then invokes its methods to (1) read the file and process the database records and (2) to generate and print the four reports as shown in the third run in example output beginning on page 4. If no command line argument is provided, the program should indicate this and end as shown in the first run in the example output on page 4. If an FileNotFoundException is thrown in the readFile method in the DBList class, it should be caught in the catch block of the try statement in main. The catch block should print a message (“*** Attempted to read file: ” along with the exception’s message). For example, if the user entered “nofile.csv” as the command line argument and this file does not exit, then the Run I/O in jGRASP would look like the second run in the example output beginning on page 4). Note that since the main method is catching FileNotFoundException, it no longer needs the throws clause in its declaration.

Code and Test: See examples of exception handling in the text and the class notes. Download database_data_2_exceptions.csv from the assignment page in Canvas to test your program. One of your optional JUnit test methods should call your main method with no argument (i.e., an empty String array). Another should call your main method with an argument that is not a valid file name to ensure that your catch block is covered. Finally, a third should call your main method with an argument that is the file name above. See “Code and Test” for DBPart2 in Part 2 to see how to invoke your main method.

Example Output

Three separate runs are shown below: (1) one with no command line argument, (2) one with an invalid file name as command line argument, and (3) one with valid file name as command line argument.

MM«M —-jGRASP exec: java DBPart3
MM§MFile name expected as command line argument. MM§MProgram ending. MM§M MM©M —-jGRASP: operation complete.
MMMM
MM«M —-jGRASP exec: java DBPart3 NotAFile.csv
MM§M *** Attempted to read file: NotAFile.csv (No such file or directory)
MM§M MM©M —-jGRASP: operation complete.
MMMM
MM«M —-jGRASP exec: java DBPart3 database_data_2_exceptions.csv
MM§M——————————- MM§MMonthly Database Report
MM§M——————————-
MM§MDatabase One (class CentralizedDB) Monthly Cost: $2,700.00
MM§MStorage: 5.000 TB
MM§MBase Cost: $1,200.00
MM§MLicense: $1,500.00
MM§M
MM§MDatabase Two (class DistributedDB) Monthly Cost: $3,320.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $12.00
MM§MUser Cost: $1,200.00
MM§MCost Factor: 1.1
MM§M
MM§MDatabase Three (class HomogeneousDB) Monthly Cost: $3,680.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $14.00
MM§MUser Cost: $1,400.00
MM§MCost Factor: 1.2
MM§M
MM§MDatabase Four (class HeterogeneousDB) Monthly Cost: $3,820.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $14.00
MM§MUser Cost: $1,400.00
MM§MCost Factor: 1.3

MM§M
MM§M—————————————– MM§MMonthly Database Report (by Name)
MM§M—————————————–
MM§MDatabase Four (class HeterogeneousDB) Monthly Cost: $3,820.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $14.00
MM§MUser Cost: $1,400.00
MM§MCost Factor: 1.3
MM§M
MM§MDatabase One (class CentralizedDB) Monthly Cost: $2,700.00
MM§MStorage: 5.000 TB
MM§MBase Cost: $1,200.00
MM§MLicense: $1,500.00
MM§M
MM§MDatabase Three (class HomogeneousDB) Monthly Cost: $3,680.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $14.00
MM§MUser Cost: $1,400.00
MM§MCost Factor: 1.2
MM§M
MM§MDatabase Two (class DistributedDB) Monthly Cost: $3,320.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $12.00
MM§MUser Cost: $1,200.00
MM§MCost Factor: 1.1
MM§M
MM§M————————————————- MM§MMonthly Database Report (by Monthly Cost)
MM§M————————————————-
MM§MDatabase Four (class HeterogeneousDB) Monthly Cost: $3,820.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $14.00
MM§MUser Cost: $1,400.00
MM§MCost Factor: 1.3
MM§M
MM§MDatabase Three (class HomogeneousDB) Monthly Cost: $3,680.00
MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $14.00
MM§MUser Cost: $1,400.00
MM§MCost Factor: 1.2
MM§M
MM§MDatabase Two (class DistributedDB) Monthly Cost: $3,320.00 MM§MStorage: 7.500 TB
MM§MBase Cost: $2,000.00
MM§MNumber of Users: 100
MM§MCost per User: $12.00
MM§MUser Cost: $1,200.00
MM§MCost Factor: 1.1
MM§M
MM§MDatabase One (class CentralizedDB) Monthly Cost: $2,700.00 MM§MStorage: 5.000 TB
MM§MBase Cost: $1,200.00
MM§MLicense: $1,500.00 MM§M
MM§M———————-
MM§MInvalid Records Report
MM§M———————-
MM§MD,Database Two Alt,2000.0,7.5,100
MM§Mjava.util.NoSuchElementException: For missing input data
MM§M
MM§MH,Database Three Alt,2000.o,7.5,100,14.0
MM§Mjava.lang.NumberFormatException: For input string: “2000.o”
MM§M
MM§MZ,Database Zero,2000.0,7.5,100,16.0 MM§MInvalidCategoryException: For category: Z
MM§M
MM§M
MM§M
MM©M —-jGRASP: operation complete.

Notes
1. This project assumes that you are reading each double value as a String using next() and then parsing it into a double with Double.parseDouble(…) as shown in the following example. . . . Double.parseDouble(myInput.next());
This form of input will throw a java.lang.NumberFormatException if the value is not a double.

If you are reading in each double value as a double using nextDouble(), for example
. . . myInput.nextDouble(); then a java.util.InputMismatchException will be thrown if the value read in is not a double.

For this assignment, you should change your input to use Double.parseDouble(…) rather than nextDouble(), since Web-CAT is looking for NumberFormatException rather than java.util.InputMismatchException.

2. If you are using the JUnit Assert.assertArrayEquals method to check two DB arrays for equality, then the equals and hashCode methods must be implemented in your DB class; that is, Assert.assertArrayEquals calls equals(Object obj) on each object in the array, so DB must have an equals method that overrides the one inherited from the Object class. If the DB class does not override equals(Object obj), then the JUnit Assert.assertArrayEquals method will use the inherited equals(Object obj) method which means two DB arrays will be equal only if they are the same object
(i.e., aliases).

Below is a simplified equals method and hashCode method you are free to use.

public boolean equals(Object obj) { if (!(obj instanceof DB)) { return false;
} else {
DB d = (DB) obj;
return (name.equalsIgnoreCase(d.getName()));
}
} public int hashCode() { return 0;
}