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// enums/PostOffice.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Modeling a post office
import java.util.*;
import onjava.*;
class Mail {
// The NO's reduce probability of random selection:
enum GeneralDelivery {YES,NO1,NO2,NO3,NO4,NO5}
enum Scannability {UNSCANNABLE,YES1,YES2,YES3,YES4}
enum Readability {ILLEGIBLE,YES1,YES2,YES3,YES4}
enum Address {INCORRECT,OK1,OK2,OK3,OK4,OK5,OK6}
enum ReturnAddress {MISSING,OK1,OK2,OK3,OK4,OK5}
GeneralDelivery generalDelivery;
Scannability scannability;
Readability readability;
Address address;
ReturnAddress returnAddress;
static long counter = 0;
long id = counter++;
@Override public String toString() {
return "Mail " + id;
}
public String details() {
return toString() +
", General Delivery: " + generalDelivery +
", Address Scannability: " + scannability +
", Address Readability: " + readability +
", Address Address: " + address +
", Return address: " + returnAddress;
}
// Generate test Mail:
public static Mail randomMail() {
Mail m = new Mail();
m.generalDelivery =
Enums.random(GeneralDelivery.class);
m.scannability =
Enums.random(Scannability.class);
m.readability =
Enums.random(Readability.class);
m.address = Enums.random(Address.class);
m.returnAddress =
Enums.random(ReturnAddress.class);
return m;
}
public static
Iterable<Mail> generator(final int count) {
return new Iterable<Mail>() {
int n = count;
@Override public Iterator<Mail> iterator() {
return new Iterator<Mail>() {
@Override public boolean hasNext() {
return n-- > 0;
}
@Override public Mail next() {
return randomMail();
}
@Override
public void remove() { // Not implemented
throw new UnsupportedOperationException();
}
};
}
};
}
}
public class PostOffice {
enum MailHandler {
GENERAL_DELIVERY {
@Override boolean handle(Mail m) {
switch(m.generalDelivery) {
case YES:
System.out.println(
"Using general delivery for " + m);
return true;
default: return false;
}
}
},
MACHINE_SCAN {
@Override boolean handle(Mail m) {
switch(m.scannability) {
case UNSCANNABLE: return false;
default:
switch(m.address) {
case INCORRECT: return false;
default:
System.out.println(
"Delivering "+ m + " automatically");
return true;
}
}
}
},
VISUAL_INSPECTION {
@Override boolean handle(Mail m) {
switch(m.readability) {
case ILLEGIBLE: return false;
default:
switch(m.address) {
case INCORRECT: return false;
default:
System.out.println(
"Delivering " + m + " normally");
return true;
}
}
}
},
RETURN_TO_SENDER {
@Override boolean handle(Mail m) {
switch(m.returnAddress) {
case MISSING: return false;
default:
System.out.println(
"Returning " + m + " to sender");
return true;
}
}
};
abstract boolean handle(Mail m);
}
static void handle(Mail m) {
for(MailHandler handler : MailHandler.values())
if(handler.handle(m))
return;
System.out.println(m + " is a dead letter");
}
public static void main(String[] args) {
for(Mail mail : Mail.generator(10)) {
System.out.println(mail.details());
handle(mail);
System.out.println("*****");
}
}
}
/* Output:
Mail 0, General Delivery: NO2, Address Scannability:
UNSCANNABLE, Address Readability: YES3, Address
Address: OK1, Return address: OK1
Delivering Mail 0 normally
*****
Mail 1, General Delivery: NO5, Address Scannability:
YES3, Address Readability: ILLEGIBLE, Address Address:
OK5, Return address: OK1
Delivering Mail 1 automatically
*****
Mail 2, General Delivery: YES, Address Scannability:
YES3, Address Readability: YES1, Address Address: OK1,
Return address: OK5
Using general delivery for Mail 2
*****
Mail 3, General Delivery: NO4, Address Scannability:
YES3, Address Readability: YES1, Address Address:
INCORRECT, Return address: OK4
Returning Mail 3 to sender
*****
Mail 4, General Delivery: NO4, Address Scannability:
UNSCANNABLE, Address Readability: YES1, Address
Address: INCORRECT, Return address: OK2
Returning Mail 4 to sender
*****
Mail 5, General Delivery: NO3, Address Scannability:
YES1, Address Readability: ILLEGIBLE, Address Address:
OK4, Return address: OK2
Delivering Mail 5 automatically
*****
Mail 6, General Delivery: YES, Address Scannability:
YES4, Address Readability: ILLEGIBLE, Address Address:
OK4, Return address: OK4
Using general delivery for Mail 6
*****
Mail 7, General Delivery: YES, Address Scannability:
YES3, Address Readability: YES4, Address Address: OK2,
Return address: MISSING
Using general delivery for Mail 7
*****
Mail 8, General Delivery: NO3, Address Scannability:
YES1, Address Readability: YES3, Address Address:
INCORRECT, Return address: MISSING
Mail 8 is a dead letter
*****
Mail 9, General Delivery: NO1, Address Scannability:
UNSCANNABLE, Address Readability: YES2, Address
Address: OK1, Return address: OK4
Delivering Mail 9 normally
*****
*/