Im doing exercise 9-1: Create and work with interfaces; in the Murach's java programming 4th edition.
4) Edit the Product class so it implements the Displayable interface. The getDisplayText method in this class should format a string that can be used to display the product information.
5) Edit the Employee class so it Implements the DepartmentConstants and Displayable interfaces. The getDisplayText method in this class should work like the one in the Product class, and it should use the constants in the DepartmentConstants interface to include the department name in the return value.
6) Open the DisplayableTestApp class and code to it that creates an Employee object, assigns it to a Displayable variable, and displays the information in the Employee object at the console. To get the information for an employee, you'll need to use the getDisplayText method of the Displayable interface.
7) Run the application to make sure that it displays the employee information.
8) Repeat steps 6 and 7 for a Product object.
9) Open the DisplayableTestApp class and add a method with this signature: private static String displayMultiple(Displayable d, int count)
write the code for this method so it returns a string that contains the Displayable parameter the number of times specified by the int parameter.
10) Modify the code in the main method so it uses the displayMultiple method to display the employee information once and the product information twice.
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