The GRASP Demo

The purpose of this exercise is to practice using GRASP (Information Expert, Low Coupling and High Cohesion).

Estimated workload of this exercise is 30 min.

Description

In this exercise you should modify the provided Java code according to the Information Expert principle. The code must comply with the principles of Low Coupling and High Cohesion. This will help you learn how to apply these principles in Java programs.

Details

1. Modify the Person class according to the basic principles of OOP.
2. Driving licenses are available to persons over 18 years of age. Provide driver's license eligibility checks for objects of the Person class.
3. Implement the isEligibleForDrivingLicense method according to the Information Expert principle.
4. After making changes, the InformationExpertViolation class will no longer be needed. Get rid of it.
5. Modify the Employee and Salary classes according to the principles of Low Coupling and High Cohesion.
6. Implement the Employee.splitName() method. It should return an array where the first element is the first name and the second is the last name.

Example

An example of a violation of the Information Expert principle is shown below.

Person alice = new Person("Alice", 20);
boolean isAliceEligible = InformationExpertViolation.isEligibleForDrivingLicense(alice);
LOGGER.log(System.Logger.Level.INFO, "Is Alice eligible for driving license? " + isAliceEligible);

Person john = new Person("John", 17);
boolean isJohnEligible = InformationExpertViolation.isEligibleForDrivingLicense(john);
LOGGER.log(System.Logger.Level.INFO, "Is John eligible for driving license? " + isJohnEligible);

An example of the output of the previous code is shown below.

...
INFO: Is Alice eligible for driving license? true
...
INFO: Is John eligible for driving license? false
...

An example of a violation of the Low Coupling and High Cohesion principles is shown below.

DefectiveEmployee employee = new DefectiveEmployee("John Doe", 3000, 10, 20);

String[] nameParts = employee.splitName();
LOGGER.log(System.Logger.Level.INFO, "First Name: " + nameParts[0]);
LOGGER.log(System.Logger.Level.INFO, "Last Name: " + nameParts[1]);

LOGGER.log(System.Logger.Level.INFO, "Total Salary:  " + employee.calculateTotalSalary());
LOGGER.log(System.Logger.Level.INFO, "Hourly Salary: " + employee.calculateHourlySalary());

An example of the output of the previous code is shown below..

...
INFO: First Name: John
...
INFO: Last Name: Doe
...
INFO: Total Salary:  3200
...
INFO: Hourly Salary: 200
...