1. Design a Java interface called Priority that includes two methods: setPriority and getPriority. This interface would define a way to establish numeric priority among a set of objects. Your numeric priority values should be on a scale. For easy comparing of priorities, make 1 the lowest priority. It should be more complex than just 1, 2, 3 (low, medium, high). Define constants in the interface for the low, medium, and high priority values. Design and implement a class called Task that represents a task (e.g., something on a to-do list) that implements the Priority interface from above, as well as the Comparable interface from the Java standard class library. A task should have some sort of description. Illustrate your design with a UML class diagram. Create a driver whose main method exercises some Task objects. Make sure you have enough tasks to produce comparisons where a given task is higher, lower, or equal in priority to some other task. Implement the interface such that the tasks are ranked by priority. Create a driver class that shows these new features of Task objects.

2. Design a Java interface called Lockable that includes the following methods: setKey, lock, unlock, and locked. The setKey, lock, and unlock methods take an integer parameter that represent the key. The setKey method establishes the key. The lock and unlock methods lock and unlock the object, but only if the key passed in is correct. The locked method returns a boolean that indicates whether or not the object is locked. A Lockable object represents an object whose regular methods are protected. If the object is locked, then the methods cannot be invoked; if it is unlocked, they can be invoked. Now, redesign the Coin class (Listing 5.4, p. 186) and Account class (Listing 5.7, p. 192) from Chapter 5 in your course textbook so that they are Lockable. Create a driver class to demonstrate the behaviours of Lockable objects using Account and Coin classes.