Java - Stuck again...

[tomoki]

Hi, I'm stuck again... and this time it's gonna be more frustrating than the last because I'm getting confused on which loop to be using for what purpose. I had help from some friends so... it got me that far. 

 

The method I'm working on // returns the number of winners in a given year (e.g. 2, in 1993). Should I be using keys with iterator? I just learnt that. 

 

 

So this is what my code looks like thus far:

import java.util.HashMap;
import java.util.Set;
import java.util.Iterator;
import java.util.Collection;

/**
 * This class describes the winners of the Nobel Prize in Peace between the years 1993 and 2009.
 * @author: Dominic Ng
 * @version: 1.0
 */
class NobelPrizeWinners{
    private HashMap<Integer, String[]> winner;

    /**
     * This is the first constructor which creates a HashMap that puts an array of Strings with winners associated by year. 
     */
    public NobelPrizeWinners(){
        winner = new HashMap<Integer, String[]>();

        winner.put(2009, new String[]{"Barack H. Obama"});
        winner.put(2008, new String[]{"Martti Ahtisaari"});
        winner.put(2007, new String[]{"Intergovernmental Panel on Climate Change (IPCC)","Albert Arnold (Al) Gore Jr."});
        winner.put(2006, new String[]{"Muhammad Yunus", "Grameen Bank"});
        winner.put(2005, new String[]{"International Atomic Energy Agency (IAEA)" , "Mohamed ElBaradei"});
        winner.put(2004, new String[]{"Wangari Muta Maathai"});
        winner.put(2003, new String[]{"Shirin Ebadi"});
        winner.put(2002, new String[]{"Jimmy Carter"});
        winner.put(2001, new String[]{"United Nations (U.N.)" , "Kofi Annan"});
        winner.put(2000, new String[]{"Kim Dae-jung"});
        winner.put(1999, new String[]{"Médecins Sans Frontières"});
        winner.put(1998, new String[]{"John Hume, David Trimble"});
        winner.put(1997, new String[]{"International Campaign to Ban Landmines (ICBL)" , "Jody Williams"});
        winner.put(1996, new String[]{"Carlos Filipe Ximenes Belo, José Ramos-Horta"});
        winner.put(1995, new String[]{"Joseph Rotblat, Pugwash Conferences on Science and World Affairs"});
        winner.put(1994, new String[]{"Yasser Arafat, Shimon Peres, Yitzhak Rabin"});
        winner.put(1993, new String[]{"Nelson Mandela", "Frederik Willem de Klerk"});

    }
    
    /**
     * @return the number of winners of given year. 
     */
    public int getNumberOfWinners(){
        int r = 0;
        Collection<String[]> s = winner.values();
        Iterator<String[]> it = s.iterator();
        while(it.hasNext()){
            String[] w = it.next();
            r += w.length; // r = r + w.length;
        }
        return r;
    }
    
    public int getNumberOfWinnersForYear(int year){
        
    }
}

[elpiop]

don't you just need to return

winner.get(year).length ?

that will tell you the length of the array (number of winners i guess?) for whatever year value you input

[tomoki]

6 minutes ago, elpiop said:

don't you just need to return

winner.get(year).length ?

that will tell you the length of the array (number of winners i guess?) for whatever year value you input

 

It...was that simple?!? What... @#$*&%^!@%$ thank you... 

I thought I had to make a loop and check the number of winners... so I kept making Iterator & Collection ones like I did in the previous method. Then it didn't work and I tried making a while loop as well as a for-each loop. 

[elpiop]

26 minutes ago, tomoki said:

 

It...was that simple?!? What... @#$*&%^!@%$ thank you... 

I thought I had to make a loop and check the number of winners... so I kept making Iterator & Collection ones like I did in the previous method. Then it didn't work and I tried making a while loop as well as a for-each loop. 

well you could do something like this using an enhanced for loop

 

public int getNumberOfWinnersForYear(int year){
    	for ( Map.Entry<Integer, String[]> entry : winner.entrySet()) {
    	    Integer key = entry.getKey();
    	    String[] winners = entry.getValue();
    	    if(year == key)
    	    {
    	    	return winners.length; //return length of array (number of winners for that year)
    	    }
   	    
    	}
		return 0; //no winners
    }

however, since the get() method can be called on a hashmap, you can retrieve the entry, which in this case is your string array of winners, and then get its length easily, so no loop like this is necessary.

[straight_stewie]

I can never figure out why Java considers the "dictionary" type obsolete. It is so much easier because you could just do this:

public int GetWinners(int year)
{
	return myDictionary[year].Length;
}

Alternatively, what @elpiop said.