This is somewhat related to my previous question but I've realised that I needed to deal with the issue of nesting earlier in the problem, so here's where I am. (I'm also not far off being a beginner in Java, so please bear with me).
I'm creating a simple booking system for 5 rooms which will take in names, times, room numbers and days. This has to be done using nested TreeMaps. Here's the layout of the data as I see it, where paretheses represent the boundaries of a TreeMap:
(Day, (Room #, (Time, Name)))
As far as I can see, I need one TreeMap for times and names, one for each room, then one for each day. That means one time/name treemap per room per day, which means 1 x 5 x 7 = 35 TreeMaps. Like this:
{Mon, [Room 1, (0600, NameA
0630, NameB
0700, NameC)
Room 2, (0600, NameD
0630, NameE)
Room 3, (0600, NameF
0630, NameG)]
Tues, [Room 1, (0600, Name1
0630, Name2)
Room 2, (0600, Name3
0630, Name4
0700, Name5)]}
(the different bracket types represent the boundaries of the nested TreeMaps)
Having come to that conclusion, my next problem is iterating through a loop to create all those TreeMaps. I can't seem to dynamically generate the TreeMaps using a for loop, because I can't stick a counter's variable number onto the newly-created TreeMap's name.
I did have this:
TreeMap keyDay = new TreeMap();
TreeMap keyRoom = new TreeMap();
TreeMap keyTime = new TreeMap();
but it is only three, which is clearly not enough to allow for duplication of keys - any new entries for e.g. '0900' (time key) or e.g. 'Room 1' (room key) will overwrite the old ones.
Does anyone have any suggestions? Would be much appreciated :)
I agree it is really super mega bad. But if you want to implement this functionality, I recommend HashMaps instead. Here is a class that implements the functionality you want:
public class Reservations {
static final int DAY_SUN = 0, DAY_MON = 1, DAY_TUE = 2, DAY_WED = 3, DAY_THU = 4, DAY_FRI = 5, DAY_SAT = 6;
static final int ROOM_1 = 0, ROOM_2 = 1, ROOM_3 = 2, ROOM_4 = 3, ROOM_5 = 4;
private static HashMap<Integer[], String[]> hMap = new HashMap<Integer[], String[]>();
static String [] getStringForValue(Integer[] i){
return hMap.get(i);
}
static TreeSet<String> getOrderedOutputStrings(){
TreeSet<String> set = new TreeSet<String>();
for(Entry<Integer[],String[]> e : hMap.entrySet()){
int day_int = Reservations.getDay(e.getKey());
int room_int = Reservations.getRoom(e.getKey());
int time = Reservations.getTime(e.getValue());
String name = Reservations.getGuestName(e.getValue());
String day = Reservations.dayToString(day_int);
String room = Reservations.roomToString(room_int);
if(time > 0)
set.add("DAY: " + "(" + day_int + ")" + day + " (" + room_int + ")"+ "ROOM: " + room + " :: " + name + " @ " + time);
}
return set;
}
static void setupMap() {
for (int day = 0; day < 7; day++) {
for (int room = 0; room < 5; room++) {
addGuest(day, room, (int)(Math.random()*1000), "Bob TestCase");
}
}
}
static void addGuest(int day, int room, int time, String name) {
Integer[] ref = new Integer[2];
ref[0] = day;
ref[1] = room;
String[] s = new String[2];
s[0] = Integer.toString(time);
s[1] = name;
hMap.put(ref, s);
}
static String[] lookupRoom(int day, int room) {
Integer[] i = new Integer[2];
i[0] = day;
i[1] = room;
return hMap.get(i);
}
static int getDay(Integer[] i){
return i[0];
}
static int getRoom(Integer[] i ){
return i[1];
}
static int getTime(String[] s) {
return Integer.parseInt(s[0]);
}
public static String getGuestName(String[] s) {
return s[1];
}
public static String dayToString(int i){
switch(i){
case 0:
return "SUNDAY";
case 1:
return "MONDAY";
case 2:
return "TUESDAY";
case 3:
return "WEDNESDAY";
case 4:
return "THURSDAY";
case 5:
return "FRIDAY";
case 6:
return "SATURDAY";
default:
return null;
}
}
public static String roomToString(int i){
switch(i){
case 0:
return "ROOM ONE";
case 1:
return "ROOM TWO";
case 2:
return "ROOM THREE";
case 3:
return "ROOM FOUR";
case 4:
return "ROOM FIVE";
default:
return null;
}
}
}
Here is a main that runs the Reservations class:
public class Main {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Reservations.setupMap(); //Run to test TODO: remove setupMap() from Reservation class
Reservations.addGuest(Reservations.DAY_MON, Reservations.ROOM_2, 1230, "John Doe");
TreeSet<String> set = new TreeSet<String>();
for(String s: Reservations.getOrderedOutputStrings()){
System.out.println(s + "\n");
}
}
}
And finally, using SetupMap and the single entry, it produces:
DAY: (0)SUNDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 423
DAY: (0)SUNDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 637
DAY: (0)SUNDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 731
DAY: (0)SUNDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 424
DAY: (0)SUNDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 427
DAY: (1)MONDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 335
DAY: (1)MONDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 580
DAY: (1)MONDAY (1)ROOM: ROOM TWO :: John Doe @ 1230
DAY: (1)MONDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 700
DAY: (1)MONDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 556
DAY: (1)MONDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 92
DAY: (2)TUESDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 84
DAY: (2)TUESDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 964
DAY: (2)TUESDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 981
DAY: (2)TUESDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 294
DAY: (2)TUESDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 22
DAY: (3)WEDNESDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 216
DAY: (3)WEDNESDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 838
DAY: (3)WEDNESDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 198
DAY: (3)WEDNESDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 494
DAY: (3)WEDNESDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 796
DAY: (4)THURSDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 617
DAY: (4)THURSDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 866
DAY: (4)THURSDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 799
DAY: (4)THURSDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 242
DAY: (4)THURSDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 178
DAY: (5)FRIDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 491
DAY: (5)FRIDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 16
DAY: (5)FRIDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 838
DAY: (5)FRIDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 63
DAY: (5)FRIDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 860
DAY: (6)SATURDAY (0)ROOM: ROOM ONE :: Bob TestCase @ 73
DAY: (6)SATURDAY (1)ROOM: ROOM TWO :: Bob TestCase @ 759
DAY: (6)SATURDAY (2)ROOM: ROOM THREE :: Bob TestCase @ 15
DAY: (6)SATURDAY (3)ROOM: ROOM FOUR :: Bob TestCase @ 115
DAY: (6)SATURDAY (4)ROOM: ROOM FIVE :: Bob TestCase @ 21
That result was generated in less than a single second. I promise that is infinitely more efficient than nested TreeMaps. Good Luck!