Dynamic Arrays In Java

[Brian Mulvany]

Hi
I have a set of Java classes that parse a website looking for cd's. The amount of cd's vary depending on the search. I want to be able to sort the search results by price, album, artist etc. I figure one way to do this might be to use a dynamic array to store the results. I dont know how to do one of these or where to start. Has anybody here got any useful guidelines or hints as to where I can go and start.
Thanks
Brian

[Horatio Westock]

If you need dynamically sized collections of things, I recommend you read the Collections Trail. I'm sure you will find some interesting stuff there on storing and sorting collections of objects.

[Yevgeniy Treyvus]

Hey Brian,

I wrote a simple example for you that should get you started. But I think once you get into it, you will see that you will probably need to make improvements in order to make it useful in your application.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
 
 
 
public class CDRecord implements Comparable {
 
public static final int MAX_COLUMNS = 4;
private String[] cdDetails;
private static int colummToSortBy = -1;

public CDRecord(String[] details) {
cdDetails = details;
}

public int compareTo(Object o) {
CDRecord otherRecord = (CDRecord)o;
return cdDetails[colummToSortBy].compareTo(otherRecord.cdDetails[colummToSortBy]);
}

public String toString() {
return cdDetails[0] + "\t" + 
cdDetails[1] + "\t" + 
cdDetails[2] + "\t" + 
cdDetails[3] + "\n"; 
}

public static void main(String[] args) {
List cds = new ArrayList();
cds.add(new CDRecord(new String[] {
"Matchbox 20","Best Hits","19.99","1999"
}));
cds.add(new CDRecord(new String[] {
"Titaniums","Metal Hits 101","27.99","1967"
}));
cds.add(new CDRecord(new String[] {
"Abracadabra","Magic Touch","14.99","2003"
}));
 
for(int i=0; i<MAX_COLUMNS; i++) {
System.out.println("Sorting by column " + (i+1) + " ...");
colummToSortBy = i;
Collections.sort(cds);
System.out.println(cds);
System.out.println();
}

}
}

By the way here's the corresponding output:

Sorting by column 1 ...
[AbracadabraMagic Touch14.992003
, Matchbox 20Best Hits19.991999
, TitaniumsMetal Hits 10127.991967
]

Sorting by column 2 ...
[Matchbox 20Best Hits19.991999
, AbracadabraMagic Touch14.992003
, TitaniumsMetal Hits 10127.991967
]

Sorting by column 3 ...
[AbracadabraMagic Touch14.992003
, Matchbox 20Best Hits19.991999
, TitaniumsMetal Hits 10127.991967
]

Sorting by column 4 ...
[TitaniumsMetal Hits 10127.991967
, Matchbox 20Best Hits19.991999
, AbracadabraMagic Touch14.992003
]
[ April 01, 2005: Message edited by: Yevgeniy Treyvus ]