Problem extracting the values in the desired format

[Whisperer]

Hi,

I have created a map with a String as Key and an ArrayList of Integer values.

The output I want is:
Reading Applicants Numbers
5+ Bed House : 12
Two Bed Flat : 124 17 45 503
One Bed Flat : 47 140 274
3/4 Bed House : 101 97 250
2 Bed House : 198 64

The output I can get is:
Reading Applicants Numbers
5+ Bed House : [12]
Two Bed Flat : [124, 17, 45, 503]
One Bed Flat : [47, 140, 274]
3/4 Bed House : [101, 97, 250]
2 Bed House : [198, 64]

My code to place the information in to the map is:

   /**
    * Allocates the applicants to the Houses
    */
   public void makeApplications(String[] houseNames, Integer[][] applicants)
   {  
      Map<String, ArrayList<Integer>> holdMap = 
          new HashMap<String, ArrayList<Integer>>();
      for(int houseName = 0; houseName < houseNames.length; houseName++)  
      {
         ArrayList<Integer> applicant = new ArrayList<Integer>();
         for(int appNum = 0; appNum < applicants[houseName].length; appNum++)
         {
            applicant.add(applicants[houseName][appNum]);
         }
         holdMap.put(houseNames[houseName], applicant);
      }
      this.houseNameMap = holdMap;
   }

My problem lies in that I am able to get the values for each key but am unable to 'convert' the object returned by the getKey to the format that I require - break open the object

My current code is:

   public void printTownApps()//
   {
      System.out.println(this.getTownName() + Space + "Applicants Numbers");
      for (Object house : houseNameMap.keySet())
      {
         System.out.print(house + " : " );
//Instead of printing I need to decode the result from get(house) to a String perhaps? :smash:
         System.out.println(houseNameMap.get(house));
      }
      System.out.println();
   }

Your help would be greatly appreciated
GT

[sunde887]

The default behavior of all collections, when printed is:

public String toString() {
        Iterator<E> i = iterator();
	if (! i.hasNext())
	    return "[]";

	StringBuilder sb = new StringBuilder();
	sb.append('[');
	for (;;) {
	    E e = i.next();
	    sb.append(e == this ? "(this Collection)" : e);
	    if (! i.hasNext())
		return sb.append(']').toString();
	    sb.append(", ");
	}
    }

It basically loops through, but appends a [ in the front and ] at the end. To remedy this, just manually loop through the array list.

Something like

List<Integer> numbers = houseNameMap.get(house);

From there you can build a string with a string builder and iterating over the list.

[Whisperer]

Thanks sunde887,

I placed your line in the print method thus:

   public void printTownApps()//
   {
      System.out.println(this.getTownName() + Space + "Applicants Numbers");
      for (Object house : houseNameMap.keySet())
      {
         System.out.print(house + " : " );
         List<Integer> numbers = houseNameMap.get(house);
         System.out.println(houseNameMap.get(house));
      }
      System.out.println();
   }

but when I compiled I got the following

incompatible types - found java.lang.Object but expected java.util.list<java.lang.Integer>

I think that this is because the values returned are an array of arrays of integer values.
My test code I used to load the two methods is

String[]houseNames = {"One Bed Flat", "Two Bed Flat", "2 Bed House",
"3/4 Bed House", "5+ Bed House"};
Integer[][]applicants = {{47, 140, 274}, {124, 17, 45, 503},
{198, 64}, {101, 97, 250}, {12}};
Town Reading = new Town("Reading");
Reading.makeApplications(houseNames, applicants);

followed by:

Reading.printTownApps();

HTH - GT

[sunde887]

Which line gives that error?

[Whisperer]

The inserted line in the print routine, I just did a compile check and had not got as far as trying to build the resulting string.

List<Integer> numbers = houseNameMap.get(house);

GT

[Tolls]

What's houseNameMap defined as?

[Whisperer]

full declaration the same as holdMap in makeApplications()

Map<String, ArrayList<Integer>> houseNameMap = new HashMap<String, ArrayList<Integer>> ();

[Tolls]

Then this:
List<Integer> numbers = houseNameMap.get(house);
Should be fine.
Why are you doing this?

      for (Object house : houseNameMap.keySet())

and not

      for (String house : houseNameMap.keySet())

since the keySey is a set of Strings?

[Whisperer]

If I do use String it throws an exception

incompatible types - found java.lang.Object but expected java.lang.String

[Tolls]

That tells me that houseNameMap is not defined the way you think it is.
That looks like its a raw type.

[Whisperer]

Would you like the complete class code, its not much longer?

[Tolls]

I'm about to sign off, but if you're quick.

[Whisperer]

import java.util.*;


public class Town
{
   // instance variables
   private String townName;
   private Map houseNameMap;
   private String Space;

   /**
    * Constructor for objects of class Town
    */
   public Town(String town)
   {
      townName = town;
      Map<String, ArrayList<Integer>> houseNameMap = 
          new HashMap<String, ArrayList<Integer>>();
//      Set the length of Space according to the length of the Town next
      Space = "         "; 
   }

   /**
    * Returns the name of the town
    */
   public String getTownName()
   {
      return this.townName;
   }
   
   /**
    * Allocates the applicants to the Houses
    */
   public void makeApplications(String[] houseNames, Integer[][] applicants)
   {  
      Map<String, ArrayList<Integer>> holdMap = 
          new HashMap<String, ArrayList<Integer>>();
      for(int houseName = 0; houseName < houseNames.length; houseName++)  
      {
         ArrayList<Integer> applicant = new ArrayList<Integer>();
         for(int appNum = 0; appNum < applicants[houseName].length; appNum++)
         {
            applicant.add(applicants[houseName][appNum]);
         }
         holdMap.put(houseNames[houseName], applicant);
      }
      this.houseNameMap = holdMap;
   }

   /**
    * Prints the applicants to the standard output device
    */
   public void printTownApps()//
   {
      System.out.println(this.getTownName() + Space + "Applicants Numbers");
      for (Object house : houseNameMap.keySet())
      {
         System.out.print(house + " : " );
 //        List<Integer> numbers = houseNameMap.get(house);
         System.out.println(houseNameMap.get(house));
      }
      System.out.println();
   }

}

[Tolls]

private Map houseNameMap;

There you go.
That should be Map<String, List<Integer>>.

[Whisperer]

Thanks very much having another look at the whole lot with that revision incorporated
I suspect I shall have to change the way in which I load it in MakeApplications()
GT

[Whisperer]

Problem solved and something simple re-learned, proper declarations of data is essential to good programming.

Many thanks sundee and Tolls

[Tolls]

There was one other thing I didn't have time to comment on:

   public Town(String town)
   {
      townName = town;
      Map<String, ArrayList<Integer>> houseNameMap = 
          new HashMap<String, ArrayList<Integer>>();
//      Set the length of Space according to the length of the Town next
      Space = "         "; 
   }

That houseMapName there is local to the constructor and is not the same one as the one decalred earlier as a class attribute.