The municipality needs a system to handle the queues at their offices. At the counter, persons in need of documents from the offices can get a unique, progressive number that defines their position in the queue. The requests are handled according to this number.

Part 1. Realize a class Request with the following attributes:

• the name of the person that issued the request (a string);
• the requests's progressive number (an integer).

• a constructor to create a new request, given a person's name and a progressive number;
• getPerson that returns the person's name;
• getNumber that returns the progressive number;
• returning a String representation of a request object, by overriding the toString method of Object.

Solution: skeleton of the class, class Request

Part 2. Realize a class Counter, each of whose objects stores a queue of requests issued at the counter. The maximum number of requests that can be in the queue is determined the moment a counter is created. The class should export the following functionalities:

• a constructor that, given a positive integer representing the maximum number of requests that can be in the queue, creates an empty counter (i.e., a counter with an empty queue),
• addRequest that, given a person's name appends a new request to the counter's queue and returns the progressive number associated to this request; if there is no room in the queue, -1 is returned;
• handleRequest that gets the next request from the queue; if there are no requests left, null is returned;
• giveUp that, given a progressive number eliminates the corresponding request from the queue; if there is no such request, nothing is done;
• waitingTime that, given a progressive number returns the number of requests that are queued before that request; if there is no such request, -1 is returned;
• toString that returns a string representation of the request object, with one request per line.

Solution: representation of the objects, skeleton of the class, class Counter

Part 3. Implement a client class for Counter that contains a static method readFromInput() that, given a Counter c:

1. reads from standard input an integer n and then n names of persons, one per line,
2. adds for each person read from input a request to counter c, and
3. returns an array containing the progressive numbers associated to the requests.

Solution

Part 4. Explain how objects are allocated in a Java program, and when and how the memory occupied by an object is again made available for other objects.

Note: You can test the code you have developed by using the class defined in the file Main.java and redirecting standard input from the example file paperopoli.txt (containing the italian names of Disney comic book characters) as follows:

C:\> java Main < paperopoli.txt