Bubble Sorting string data from Arrays in Desc/Ascending order

Question

I've run into trouble when sorting string in an array.

I'm supposed to get two different outputs from my code, but I only get the output in ascending order.

    import java.util.*;
public class nextLineArray1
{
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        String names[]=new String[12];
        System.out.println("Enter the 12 names: ");
        //Load Array
        for(int i = 0; i < 12; i++)
        {
            names[i] = input.nextLine();

        }

        //Print descending order list
        String[] descSort;
        descSort=bubbleSortDesc(names);
        System.out.println("Names listed sorted in descending order (via BubbleSort): ");
        for(int x=0; x < names.length; x++)
        {
            System.out.println(names[x]);
        }
        //Print ascending order list
        String[] ascSort;
        ascSort=bubbleSortAsc(names);
        System.out.println("Names listed sorted in ascending order (via BubbleSort): ");
        for(int z=0; z < names.length; z++)
        {
            System.out.println(names[z]);
        }
    }
    public static String[] bubbleSortDesc(String[] names)
    {
        String temp;
        int passNum, i, result;
        for(passNum=1; passNum <= 11; passNum++)
        {
            for(i = 0; i<=(11-passNum); i++)
            {
                result=names[i].compareToIgnoreCase(names[i+1]);
                if(result>0)
                {
                    temp=names[i];
                    names[i]=names[i+1];
                    names[i+1]=temp;
                }
            }
        }
        return names;

    }

    public static String[] bubbleSortAsc(String[] names)
    {
        String temp;
        int passNum, i, result;
        for(passNum=1; passNum <= 11; passNum++)
        {
            for(i = 0; i<=(11-passNum); i++)
            {
                result=names[i].compareToIgnoreCase(names[i]);
                if(result>0)
                {
                    temp=names[i-1];
                    names[i-1]=names[i];
                    names[i]=temp;
                }
            }
        }
        return names;
    }
}

An explanation of why it is only sorting in ascending order, would be more than helpful.

Thanks in advance.

Your code for 'bubbleSortAsc' and 'bubbleSortDesc' looks identical, it shouldn't be. — BevynQ
– BevynQ, Commented Mar 31, 2014 at 20:58

femtoRgon · Accepted Answer · 2014-03-31 21:05:48Z

1

Looks to me like bubbleSortDesc is sorting in ascending order, and BubbleSortAsc doesn't work at all:

            //In BubbleSortAsc
            result=names[i].compareToIgnoreCase(names[i]);
            //result == 0, since names[i] is definitely equal to names[i]
            if(result>0)
            {
                //Never reached
                temp=names[i-1];
                names[i-1]=names[i];
                names[i]=temp;
            }

So, you should have, again in BubbleSortAsc:

            result=names[i].compareToIgnoreCase(names[i+1]);
            if(result>0) //names[i] > names[i+1], so swap them.

And in BubbleSortDesc:

            result=names[i].compareToIgnoreCase(names[i+1]);
            if(result<0) // This was backwards.  If names[i] < names[i+1], you need to swap, for descending order.

edited Mar 31, 2014 at 21:05

answered Mar 31, 2014 at 20:59

femtoRgon

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Comments

Frakcool · Accepted Answer · 2014-03-31 21:25:34Z

Actually you're making it really hard

For booble sort:

Also I guess you're making it very difficult, you can sort them and print them like this:

    ...
    for(int i = 0; i < (names.length - 1); i++){
        for(int j = i; j < (names.length - 1); j++){
            if(names[j].compareToIgnoreCase(names[i]) > 0){
                String aux = names[i];
                names[i] = names[j];
                names[j] = aux;
            }
        }
    }
    for(int i = 0; i < names.length; i++){
        System.out.println(names[i]);
    }
    for(int i = 0; i < (names.length - 1); i++){
        for(int j = i; j < (names.length - 1); j++){
            if(names[j].compareToIgnoreCase(names[i]) < 0){
                String aux = names[i];
                names[i] = names[j];
                names[j] = aux;
            }
        }
    }
    for(int i = 0; i < names.length; i++){
        System.out.println(names[i]);
    }
    ...

Hope this helps

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