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I have two arrays one for temperatures and one for the cities.If two temperatures are the same the corresponding cities must be shown with alphabetical sort order.For instance

  • 24 Sydney
  • 22 Athens
  • 22 Auckland
  • 20 Barcelona

--->This is the sort code.

public static void sort(String[] x , double[] y) {
    boolean doMore = true;

    while(doMore) {    
        doMore = false;  

        for(int i=0; i< x.length-1; i++) {    
            if(y[i] == y[i+1] && x[i] < x[i+1]) {    
                String temp2 = x[i];
                x[i] = x[i+1];
                x[i+1] = temp2;    
            } else if (y[i] < y[i+1]) {    
                double temp = y[i];    
                y[i] = y[i+1];    
                y[i+1] = temp; 

                String temp2 = x[i];        
                x[i] = x[i+1];    
                x[i+1] = temp2;    
                doMore = true;    
            }//if    
        }//for 2    
    }//while    
}// sort */

The problem is that on the if(y[i] == y[i+1] && x[i] < x[i+1]) i can't just compare 2 stings with the operator >. I can't use any ready sort methods either.

Does anyone know how to sort tho strings alphabetical there?

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Can't you use compareTo? E.g. if(str1.compareTo(str2) > 0) –  cowls Dec 8 '11 at 17:15
 
No we are not supposed to use any ready methods.Thus we have to make the code ourselves. –  Stefanos Varsanis Dec 9 '11 at 18:45

2 Answers

up vote 4 down vote

String is Comparable, so you can use s1.compareTo(s2)

See String.compareTo for details; it returns -1, 0 or 1 depending on whether s1 comes before s2 lexicographically, that is to say whether s1 would stand before s2 in a dictionary.

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Thanks for the edit, didn't realize how to make the link look nice –  G. Bach Dec 8 '11 at 17:38
 
You should also stress to the OP that he is trying to do string comparison with ==. He should replace those with your compareTo also, or with string.equals(). –  CPerkins Dec 8 '11 at 18:12
 
@CPerkins As far as I can see, OP only uses == once when comparing doubles. –  G. Bach Dec 8 '11 at 18:19
1  
you're right - I got confused between x and y. I don't see single-letter variable names very often anymore. –  CPerkins Dec 8 '11 at 18:28
 
Thank you all for your responses.I finally covered it using the s1.compareTo(s2) as i couldn't find anything else. –  Stefanos Varsanis Dec 9 '11 at 20:31
up vote 1 down vote

The closest answer to your current implementation is G. Bach's; you should look into his answer for an easy solution.

Thinking a little outside the box...

You current implementation has the potential downside that your arrays could get out of sync in respect to the indexes which would end up having temperatures for the wrong cities. You could try a custom type which encapsulates both fiels and have a list of those. Something like...

public class CityTemperatureInfo implements Comparable<CityTemperatureInfo>
{
    public string cityName;
    public double temperature;

    ...
}

Then your app would use the data as a List<CityTemperatureInfo>. This would ensure the city names and temperatures are always at the same place in the list. And if you make the class comparable, you can implement the int compareTo(CityTemperatureInfo other) method which would allow you to simple call sort on your list.

usually, it is a good idea to keep related data together to avoid potential problems of the data becoming out of sync.

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