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    <p>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: </p> <pre><code>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&lt;Integer[], String[]&gt; hMap = new HashMap&lt;Integer[], String[]&gt;(); static String [] getStringForValue(Integer[] i){ return hMap.get(i); } static TreeSet&lt;String&gt; getOrderedOutputStrings(){ TreeSet&lt;String&gt; set = new TreeSet&lt;String&gt;(); for(Entry&lt;Integer[],String[]&gt; 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 &gt; 0) set.add("DAY: " + "(" + day_int + ")" + day + " (" + room_int + ")"+ "ROOM: " + room + " :: " + name + " @ " + time); } return set; } static void setupMap() { for (int day = 0; day &lt; 7; day++) { for (int room = 0; room &lt; 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; } } </code></pre> <p>}</p> <p>Here is a main that runs the Reservations class:</p> <pre><code>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&lt;String&gt; set = new TreeSet&lt;String&gt;(); for(String s: Reservations.getOrderedOutputStrings()){ System.out.println(s + "\n"); } } } </code></pre> <p>And finally, using SetupMap and the single entry, it produces:</p> <pre><code>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 </code></pre> <p>That result was generated in less than a single second. I promise that is infinitely more efficient than nested TreeMaps. Good Luck!</p>
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    1. POHow do I create nested TreeMaps?
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    1. POHow do I create nested TreeMaps?
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    1. COFor the analysis of the problem, it is entirely irrelevant whether a Tree- or a Hashmap is being used. The question is rather, whether Map is appropriate or not and if so, if Maps must be nested inside each other.
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    2. COAlthough I agree that you never really answered the question, I'm giving you +1 for effort and going the extra mile.
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    3. COI agree with bconneen - I can't use your code, but thank you for taking the time to write it!
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