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vertigo
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 Posted: Wed Dec 22, 2004 10:07 am Post subject: sorted table |
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Hello
I need to build array with Integers which should be later sorted.
What container should i use ?
Thanx
Michal
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Stefan Schulz
Guest
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| Posted: Wed Dec 22, 2004 10:56 am Post subject: Re: sorted table |
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On Wed, 22 Dec 2004 11:07:32 +0100
vertigo <ax178 (AT) wp (DOT) pl> wrote:
| Quote: | Hello
I need to build array with Integers which should be later sorted.
What container should i use ?
|
That depends. If you know how many integers you'll get, a plain old
array is likely the best. Otherwise, and ArrayList (or any other List)
is the way to go.
--
In pioneer days they used oxen for heavy pulling, and when one ox
couldn't budge a log, they didn't try to grow a larger ox. We shouldn't
be trying for bigger computers, but for more systems of computers.
--- Rear Admiral Grace Murray Hopper
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vertigo
Guest
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| Posted: Wed Dec 22, 2004 11:18 am Post subject: Re: sorted table |
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| Quote: | That depends. If you know how many integers you'll get, a plain old
array is likely the best. Otherwise, and ArrayList (or any other List)
is the way to go.
|
but, how can i sort ArrayList ? I do not see any sorting function in
ArrayList class.
What should i look for ?
Thanx
Michal
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karlheinz klingbeil
Guest
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| Posted: Wed Dec 22, 2004 11:43 am Post subject: Re: sorted table |
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vertigo schrub am Mittwoch, 22. Dezember 2004 12:18
folgendes:
| Quote: | but, how can i sort ArrayList ? I do not see any
sorting function in ArrayList class.
What should i look for ?
|
ArrayList's Superclass Connection has a Sort() method.
All you have to do is to supply it with a "Comparator"
which acutally compares 2 items and tells whether on
is greater, less or equal
Her is an example:
--------------------------------------------
ArrayList liste;
Collator coll;
Comparator compInt;
Comparator compString;
public StichwortListe() {
super();
coll =
Collator.getInstance(Locale.getDefault());
compInt = new Comparator(){
public int compare(Object o1,Object o2){
return (((StichwortItem)o1).getID() -
((StichwortItem)o2).getID() );
}
};
compString = new Comparator()
{
public int compare(Object o1,Object o2){
String s1 =
((StichwortItem)o1).getName();
String s2 =
((StichwortItem)o2).getName();
return coll.compare(s1,s2);
}
};
}
/*
* As you can see, we have 2 Comparators, one compares
* an int field in an item, the other a string
* the "Collator" is locale-dependant, it gives the
* sort-order for Strings (which in German is different
* than in English for example.
*/
/*---------------------------------------------------------
* at last, you call Collections.Sort() with your
* ArrayList (here it is "this" for this class is
* derived from ArrayList) and the desired
* Comparator (String, in this case)
*---------------------------------------------------------
*/
public void sortItems(){
Collections.sort(this,compInt);
}
--------------------------------------------
Hope this helps...
--
greetz Karlheinz Klingbeil (lunqual)
http://www.lunqual.de oder http:www.lunqual.net
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VisionSet
Guest
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| Posted: Wed Dec 22, 2004 11:56 am Post subject: Re: sorted table |
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"karlheinz klingbeil" <karlheinz-klingbeil (AT) despammed (DOT) com> wrote
| Quote: | vertigo schrub am Mittwoch, 22. Dezember 2004 12:18
folgendes:
but, how can i sort ArrayList ? I do not see any
sorting function in ArrayList class.
What should i look for ?
ArrayList's Superclass Connection has a Sort() method.
All you have to do is to supply it with a "Comparator"
which acutally compares 2 items and tells whether on
is greater, less or equal
|
You mean Collections which is not a superclass of anything, but a utility
class for sorting, searching Collection classes.
Collection is the superinterface to most of the concrete container classes
and specifies no sorting abilities.
Note one is plural the other isn't.
--
Mike W
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IchBin
Guest
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| Posted: Wed Dec 22, 2004 12:04 pm Post subject: Re: sorted table |
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vertigo wrote:
| Quote: | Hello
I need to build array with Integers which should be later sorted.
What container should i use ?
Thanx
Michal
Something different. I wrote a method to take a vector and sort it by |
converting to a sorted set, sort it and then copy back to vector and
return it. Should work just using the array code.
static Vector getSortedVector(Vector targetTree) {
SortedSet set = new TreeSet();
int setSize = targetTree.size();
// Add elements to the set
for (int i = 0; i < setSize; i++) {
set.add(targetTree.get(i));
}
// Iterating over the elements in the set
Iterator it = set.iterator();
while (it.hasNext()) {
Object element = it.next();
}
// Sort elements
String[] array = (String[]) set.toArray(new String[set.size()]);
// Clean out vector before reading
targetTree.clear();
// Add elements back to vector
for (int i = 0; i < setSize; i++) {
targetTree.add(array[i]);
}
return (targetTree);
}
--
Thanks in Advance...
IchBin
__________________________________________________________________________
'The meeting of two personalities is like the contact of two chemical
substances:
if there is any reaction, both are transformed.'
- Carl Gustav Jung, (1875-1961), psychiatrist and psychologist
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Ryan Stewart
Guest
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| Posted: Wed Dec 22, 2004 12:36 pm Post subject: Re: sorted table |
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"VisionSet" <spam (AT) ntlworld (DOT) com> wrote
| Quote: | "karlheinz klingbeil" <karlheinz-klingbeil (AT) despammed (DOT) com> wrote in message
news:cqbmjl$4o2$1 (AT) online (DOT) de...
vertigo schrub am Mittwoch, 22. Dezember 2004 12:18
folgendes:
but, how can i sort ArrayList ? I do not see any
sorting function in ArrayList class.
What should i look for ?
ArrayList's Superclass Connection has a Sort() method.
All you have to do is to supply it with a "Comparator"
which acutally compares 2 items and tells whether on
is greater, less or equal
You mean Collections which is not a superclass of anything, but a utility
class for sorting, searching Collection classes.
Collection is the superinterface to most of the concrete container classes
and specifies no sorting abilities.
Note one is plural the other isn't.
Not to mention that Integer (which the OP wants to sort) already implements |
Comparable, so writing a separate Comparator is totally redundant.
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Stefan Schulz
Guest
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| Posted: Thu Dec 23, 2004 7:11 am Post subject: Re: sorted table |
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On Wed, 22 Dec 2004 07:04:16 -0500
IchBin <weconsul (AT) ptd (DOT) net> wrote:
| Quote: | static Vector getSortedVector(Vector targetTree) {
SortedSet set = new TreeSet();
|
A Set must not contain duplicates. What if your original Vector
contained duplicate entries?
| Quote: | int setSize = targetTree.size();
// Add elements to the set
for (int i = 0; i < setSize; i++) {
set.add(targetTree.get(i));
}
|
Even if you want to use a Set, why not just do a set.addAll(targetTree)?
| Quote: | // Iterating over the elements in the set
Iterator it = set.iterator();
while (it.hasNext()) {
Object element = it.next();
}
|
This loop is totally useless.
| Quote: | // Sort elements
String[] array = (String[]) set.toArray(new
String[set.size()]);
|
Why bother using an Array here?
| Quote: | // Clean out vector before reading
targetTree.clear();
// Add elements back to vector
for (int i = 0; i < setSize; i++) {
targetTree.add(array[i]);
}
return (targetTree);
}
|
This entire method can be replaced by
Collections.sort(targetTree);
--
In pioneer days they used oxen for heavy pulling, and when one ox
couldn't budge a log, they didn't try to grow a larger ox. We shouldn't
be trying for bigger computers, but for more systems of computers.
--- Rear Admiral Grace Murray Hopper
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IchBin
Guest
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| Posted: Thu Dec 23, 2004 8:29 am Post subject: Re: sorted table |
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Stefan Schulz wrote:
| Quote: | On Wed, 22 Dec 2004 07:04:16 -0500
IchBin <weconsul (AT) ptd (DOT) net> wrote:
static Vector getSortedVector(Vector targetTree) {
SortedSet set = new TreeSet();
A Set must not contain duplicates. What if your original Vector
contained duplicate entries?
int setSize = targetTree.size();
// Add elements to the set
for (int i = 0; i < setSize; i++) {
set.add(targetTree.get(i));
}
Even if you want to use a Set, why not just do a set.addAll(targetTree)?
// Iterating over the elements in the set
Iterator it = set.iterator();
while (it.hasNext()) {
Object element = it.next();
}
This loop is totally useless.
// Sort elements
String[] array = (String[]) set.toArray(new
String[set.size()]);
Why bother using an Array here?
// Clean out vector before reading
targetTree.clear();
// Add elements back to vector
for (int i = 0; i < setSize; i++) {
targetTree.add(array[i]);
}
return (targetTree);
}
This entire method can be replaced by
Collections.sort(targetTree);
Guess I should better start learning Collections.. |
--
Thanks in Advance...
IchBin
__________________________________________________________________________
'The meeting of two personalities is like the contact of two chemical
substances:
if there is any reaction, both are transformed.'
- Carl Gustav Jung, (1875-1961), psychiatrist and psychologist
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