Alphabetizing

[carderne]

Hey all
I'm busy writing a program - as stated in an earlier post of mine - to keep a database of songs and then allow them to be listed, sorted alphabetically by track artist etc...

here are the variables:

songDis[100][4]   //nested array, 100 songs, 4 properties for each
temp[] //array to temporarily store the songDis array, while swapping around
songNum //the amount of songs
sortBy //can be 0, 1, 2 or 3 to signify whether to sort by track artist etc

Here's the part to alphabetize:

for (int a = 1; a < songNum; a++)//alphabetizing songs {
	        for (int b = a + 1; b < songNum + 1; b++) {
		      if (song[a][sortBy].compareTo(song[b][sortBy]) > 0) {
			temp = songDis[a];
			songDis[a] = songDis[b];
			songDis[b] = temp;
		       }
	          }//for b
         }//for a

It seems to work. But it sometimes just throws up completely random songs ordering...

[ShoeNinja]

can you post the code for compareTo?

[hardwired]

import java.text.*;
import java.util.Date;

public class SortingSongs {
    static DateFormat df = new SimpleDateFormat("dd MMM yyyy");
    static Object[][] songs = {
        //  track                artist           album                   date
        { "Blue Universe",  "Craig Chaquico", "Once In A Blue Universe",
                                                           getDate("01 Jun 1997") },
        { "Hymn For Her",   "Rick Braun",     "Body And Soul",
                                                           getDate("25 Jan 1997") },
        { "Magic",          "Ken Navarro",    "Smooth Sensation",
                                                           getDate("14 Oct 1997") },
        { "After The Rain", "Boney James",    "Sweet Thing",
                                                           getDate("12 Mar 1997") }
    };
    static int[] catSizes;

    public static void main(String[] args) {
        initCatSizes();
        // Sort by category, viz, column in songs.
        for(int j = 0; j < songs[0].length; j++) {
            sort(j);
            print();
            System.out.println("-----------------");
        }
    }

    private static void sort(int cat) {
        int c = 0;
        for(int j = 0; j < songs.length; j++) {
            for(int k = j+1; k < songs[j].length; k++) {
                if(cat < 3)
                    c = ((String)songs[j][cat]).compareTo((String)songs[k][cat]);
                else
                    c = ((Date)songs[j][cat]).compareTo((Date)songs[k][cat]);
                if(c > 0) {
                    Object[] temp = songs[j];
                    songs[j] = songs[k];
                    songs[k] = temp;
                }
            }
        }
    }

    private static void print() {
        for(int j = 0; j < songs.length; j++) {
            for(int k = 0; k < songs[j].length; k++) {
                String s = getString(j, k);
                int spaces = catSizes[k] - s.length();
                System.out.print(s + space(spaces));
                if(k < songs[j].length-1)
                    System.out.print("  ");
            }
            System.out.println();
        }
    }

    private static Date getDate(String s) {
        Date date = null;
        try {
            date = df.parse(s);
        } catch(ParseException e) {
            System.out.println("Parse error for: " + s);
        }
        return date;
    }

    private static void initCatSizes() {
        int numCats = songs[0].length;
        catSizes = new int[numCats];
        for(int col = 0; col < numCats; col++) {
            int max = 0;
            for(int row = 0; row < songs.length; row++) {
                int length = getString(row, col).length();
                if(length > max)
                    max = length;
            }
            catSizes[col] = max;
        }
    }

    private static String getString(int row, int col) {
        if(col == 3)
            return df.format(songs[row][col]);
        return (String)songs[row][col];
    }

    private static String space(int n) {
        String s = "";
        for(int j = 0; j < n; j++)
            s += " ";
        return s;
    }
}

[carderne]

Ok, I got my thing to work. Just had the wrong name for one of the variables.
@ShoeNinja - the compareTo() method is from the java api...

Thanks again hardwired, will try your method.