Thread: Help with hashmap and heap

Hello,

I would like to read in this file: (just a small piece of it for example)

723 Light, Matt
70 Mankins, Logan
391 Maroney, Laurence
7743 Aiken, Sam
521 Alexander, Eric
232 Andrews, Willie
12 Brady, Tom
654 Britt, Wesley
901 Smith, Le Kevin
8222 Spach, Stephen
281 Spann, Antwain
965 Thomas, Adalius
83 Welker, Wes
751 Wilfork, Vince

and put it into a hashmap to save it and call it for an heap. I have gotten it to read the file, and put the number as the "key" but for the value I just put a " " (space) because how I am reading in the file, I am using " " (space) to separate the information on the line.

Is there a way to do this with Hashmap or should I use something else. Below is my code for the hashmap and it's output.

public static Map<Integer, String> donors = new HashMap<Integer,String>();
 
public static void main(String[] args) throws IOException {
 
BufferedReader donorFile = new BufferedReader(new FileReader("donor.txt"));
 
                String[] tokens;
		String line = "";
		int ID = -1;
 
 
		while ((line = donorFile.readLine()) != null) {
 
			line = line.trim();
			tokens = line.split(" ");
			ID = Integer.parseInt(tokens[0]);
			donors.put(ID, " ");
			for (int i = 1; i < tokens.length; i++) {
				for (int j = i+1; j < tokens.length; j++) {
					 System.out.println("Donors: " + ID+ " " + "Pair: " +
					tokens[i] +"  "+ tokens[j]);
 
 
				}
			}
		}
		System.out.println(donors);
		//appearances.close();
 
	}

//printing the donor's ID and name 
//but since I am spiting the line by spaces it does this
//I want the whole name to be the "value" and the number to be the "key" 
 
Donors: 501 Pair: Vrabel, Mike
Donors: 941 Pair: Warren, Ty
Donors: 15 Pair: Washington, Kelley
Donors: 816 Pair: Moss, Randy
Donors: 614 Pair: Neal, Steve
Donors: 68 Pair: O'Callaghan, Ryan
Donors: 66 Pair: Paxton, Lonie
Donors: 35 Pair: Richardson, Mike
Donors: 367 Pair: Sanders, James
Donors: 570 Pair: Sanders, Lewis
Donors: 932 Pair: Seymour, Richard
Donors: 52 Pair: Slaughter, T.J.
Donors: 4403 Pair: Evans, Heath
Donors: 331 Pair: Faulk, Kevin
Donors: 97 Pair: Green, Jarvis
Donors: 72 Pair: Gutierrez, Matt
Donors: 6 Pair: Hanson, Chris
Donors: 371 Pair: Harrison, Rodney
Donors: 10 Pair: Gaffney, Jabar
Donors: 3 Pair: Gostkowski, Stephen
Donors: 27 Pair: Hobbs, Ellis
Donors: 71 Pair: Hochstein, Russ
Donors: 17 Pair: Jackson, Chad
Donors: 22 Pair: Jones, C.J.
Donors: 7791 Pair: Kaczur, Nick
Donors: 671 Pair: Koppen, Dan
Donors: 723 Pair: Light, Matt
Donors: 70 Pair: Mankins, Logan
Donors: 391 Pair: Maroney, Laurence
Donors: 7743 Pair: Aiken, Sam
Donors: 521 Pair: Alexander, Eric
Donors: 232 Pair: Andrews, Willie
Donors: 12 Pair: Brady, Tom
Donors: 654 Pair: Britt, Wesley
Donors: 901 Pair: Smith, Le
Donors: 901 Pair: Smith, Kevin
Donors: 901 Pair: Le Kevin
Donors: 8222 Pair: Spach, Stephen
Donors: 281 Pair: Spann, Antwain
Donors: 965 Pair: Thomas, Adalius
Donors: 83 Pair: Welker, Wes
Donors: 751 Pair: Wilfork, Vince
Donors: 771 Pair: Williams, Tank
Donors: 586 Pair: Woods, Pierre
Donors: 990 Pair: Wright, Mike
Donors: 74 Pair: Yates, Billy
Donors: 1022 Pair: Thomas, Santonio
Donors: 1611 Pair: Cassel, Matt
Donors: 38 Pair: Eckel, Kyle
Donors: 541 Pair: Bruschi, Tedy
Donors: 3815 Pair: Bryant, Fernando
Donors: 73 Pair: Martin, Jimmy
Donors: 3138 Pair: Meriweather, Brandon
Donors: 866 Pair: Thomas, David
Donors: 4220 Pair: Mixon, Tim
Donors: 348 Pair: Morris, Sammy
Donors: 41 Pair: Ventrone, Raymond
Donors: 842 Pair: Watson, Benjamin
Donors: 511 Pair: Webster, Jason
 
//printing the hashmap donors
 
{3= , 4403= , 816= , 6= , 10= , 281= , 12= , 15= , 17= , 941= , 3815= , 22= , 
932= , 27= , 391= , 570= , 3138= , 35= , 654= , 1611= , 38= , 41= , 521= , 
671= , 7791= , 771= , 52= , 541= , 901= , 68= , 70= , 71= , 614= , 751= ,
 66= , 1022= , 348= , 72= , 73= , 74= , 866= , 83= , 4220= , 331= , 8222= , 
7743= , 511= , 990= , 371= , 97= , 232= , 501= , 586= , 842= , 367= , 723= , 965= }

I want the number to be the key and the name to be the value. Because the other file (below) has numbers not names.

I 10 990
i 38 100
i 371 364
i 70 335
I 391 12
I 3138 77
i 12 88
i 521 23
I 68 1008
i 816 21
c 371 364 50
C 70 335 1009
A Section A Row 1 Seat 10
a Section B Row 2 Seat 5
a Section A Row 5 Seat 9
s 12
S 10
L
I 7791 109
i 654 33
I 97 1472
I 4220 445
a Section C Row 3 Seat 1
A Section C Row 20 Seat 3
c 654 33 3300
a Section W Row 7 Seat 1
A Section W Row 9 Seat 3
L
B 5 Section D
l

I need to use a heap to do the seating arrangements with the following priorities for the heap. I honestly don't understand this part but I'm taking it one step at a time.

I donorID priority 
Insert the donor with ID donorID and priority code priority
C donorID oldPriority newPriority 
Change the priority for donorID from oldPriority to newPriority
A seat 
Assign the seat indicated to the individual who currently has the highest priority
L 
List alphabetically, everyone who has been assigned a seat, along with their seat number
S donorID 
Lists seat assigned to donor donorID, or state that no seat has been assigned

Yes. I am having problems. I only know how to set my split to spaces, seeing that I only know how to set to spaces. the key is set correctly to the number AKA the first item in the array, but the value is split into two items. The whole name is not there. which is shown in the output that I posted earlier.

I want to be able to scan the first part of the line and set it as the key aka the number and the rest of the line as the value aka the name.

A friend told me to look into Scanner.
Quote:

"Scanner- there should be something which reads a number and something to read the remainder of the line. Start by going through the file and printing something like
number=723 name=Light, Matt"

But I am searching for this without much luck.

This sounds to me that you're asking for 2 things:

1. Use Scanner to read from a file and split the donor ID/number from the name.

Originally Posted by aiojou

"Scanner- there should be something which reads a number and something to read the remainder of the line. Start by going through the file and printing something like
number=723 name=Light, Matt"

Scanner can significantly simplify your code, but its API, imo, can be quite confusing if you're not familiar with it. Do read through Scanning (The Java™ Tutorials > Essential Classes > Basic I/O).

See also Scanner (Java Platform SE 7 ). The constructor and methods that you'll need are:

• Scanner(File source)
• boolean hasNext()
• int nextInt()
• String nextLine()

Refer to the Scanner API documentation for the description of the above methods.

Putting them together, you can read-and-split as follows:

Scanner scanner = new Scanner(file);
 
while (scanner.hasNext()) {
    int donorId = scanner.nextInt();
    String name = scanner.nextLine().trim();
    System.out.println("id:" + donorId);
    System.out.println("name:" + name);
}
 
scanner.close();

where

• file: is a File object instantiated with the path to your donor.txt file
• scanner.hasNext(): checks if there is another token available; from the Scanner class description, "A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace. The resulting tokens may then be converted into values of different types using the various next methods."
• nextInt(): gets the next token as an int; this assumes that each line starts with an integer (i.e., the donor ID/number)
• nextLine(): gets the rest of the line after the donor ID (that was earlier extracted using nextInt()) up to the line separator at the end of the line; since this includes the space character that is after the donor ID, the String returned by nextLine() needs to be trimmed.
• println(): just to show that the IDs and names have been extracted correctly.
• scanner.close(): always close the scanner once you're done with it. (Later on you should learn that the close() method should be called in a finally block.)

By using Scanner like the above, you can do away with your file-reading code that makes use of BufferedReader, as well as the rest of the String manipulation code.

2. Place ID and name into a HashMap

Originally Posted by aiojou

I want to be able to scan the first part of the line and set it as the key aka the number and the rest of the line as the value aka the name.

As you were thinking in your earlier post, after extracting the donor ID and name, you can place them into a HashMap. See HashMap (Java Platform SE 7 ). The method to use to do this is "V put(K key, V value)", where the donor ID would be the key, and the name would be the value.

Thank you I figured it out just didn't reply, but your way is cleaner. Also, is there a way to do a Heap with a Hashmap?? The only examples I see are with arraylists

A heap and a hashmap are 2 completely different things. How would you do that? Why would you even want to have a heap?

Thank you Cornix for your reply. I understand that they are two different things. In my second post I stated but not completely explained that I need to do the assignment as a priority heap. I thought it would be best to save the information from the file into an hashmap. But now I am running into the of creating the heap, for every example is showing to create the heap with an arraylist.

This sounds like a job for a PriorityQueue.

I am having problems with my switch statement.

//get the other file 
//need to read in this file, get the first token and check it 
 
String operation; 
 
try {  
 
Scanner scan = new Scanner(new File("operations.txt"));  
 
    try {  
 
       while (scan.hasNextLine()) {
 
       operation = scan.nextLine(); 
 
 
       switch(operation.toUpperCase().charAt(0)) {
 
			    	    case 'I':
			    	    	dName = scan.nextLine();
			    	    	System.out.println(dName);
			    	    case 'p':
 
			    	}   
 
			      }  
 
			      if (scan.ioException() != null)  
			      {  
			         throw scan.ioException();  
			      }  
			   }  
			   finally  
			   {  
			      scan.close();  
			   }  
			   //System.out.println(donors);
			}
			catch (Exception bow) 
			{  
 
			}

I am trying to use a switch statement to read in the First char and then if it matches make it do specific things.
But It is skipping. This code only prints out 7 of the 14 I's.

output

i 38 100
i 70 335
I 3138 77
i 521 23
i 816 21
i 654 33
I 4220 445

input

I 10 990
i 38 100
i 371 364
i 70 335
I 391 12
I 3138 77
i 12 88
i 521 23
I 68 1008
i 816 21
c 371 364 50
C 70 335 1009
A Section A Row 1 Seat 10
a Section B Row 2 Seat 5
a Section A Row 5 Seat 9
s 12
S 10
L
I 7791 109
i 654 33
I 97 1472
I 4220 445
a Section C Row 3 Seat 1
A Section C Row 20 Seat 3
c 654 33 3300
a Section W Row 7 Seat 1
A Section W Row 9 Seat 3
L
B 5 Section D
l

Thank you! That fixed it!

okay. I just edited my post. Hope that makes it better.

main.txt
operations.txt

here are the two files.

operations.txt

output.txt
operations.txt

and updated operations file that only has one input.