Re: question

On Sep 26, 11:57 am, Daniel Moyne <dmo...@xxxxxxxxxx> wrote:
Peter F wrote:
On Sep 25, 8:17 pm, Daniel Moyne <dmo...@xxxxxxxxxx> wrote:
I am building a map with the key as an integer and a list of string as
the value ; basically this is the stripped code :
import java.util.Map;
import java.util.HashMap;
import java.util.TreeMap;
import java.util.ArrayList;

public class map {
public static void main(String args[]) {
ArrayList<String>clonableDataList=new ArrayList<String>();
Map<Integer,ArrayList<String>>clonableDataMap= new
HashMap<Integer,ArrayList<String>>();
for (int i=0;i<3;i++) {
clonableDataList.removeAll(clonableDataList);
clonableDataList.add(Integer.toString(i));
clonableDataList.add(Integer.toString(i+1));
clonableDataMap.put(i,clonableDataList);

System.out.println("key="+Integer.toString(i)+"list="+clonableDataList+"**");>> }
for (Map.Entry <Integer,ArrayList<String>>
entry :clonableDataMap.entrySet()) {
ArrayList<String>aa=new ArrayList<String>(entry.getValue());

System.out.println("key="+Integer.toString(entry.getKey())+"list="+entry.getValue()+"**");

}
}}

when I run the code I get this :
key=0list=[0, 1]**
key=1list=[1, 2]**
key=2list=[2, 3]**
[2, 3]
key=2list=[2, 3]**
[2, 3]
key=1list=[2, 3]**
[2, 3]
key=0list=[2, 3]**
so apparently I get all the time the same list "2, 3" for all the the
different keys when printing my map ; what is wrong ?
Thanks.
--
Daniel Moyne
(Nulix)---------------------------------------------------------
Distribution : Ubuntu Feisty \\|||// Machine : x86_64
kernel 2.6.20-16-generic / --- \ ATI Radeon X300
KDE 3.5.7 (' o-o ')
----------------------------------------oOO-(_)-OOo--------------------------

Nothing is wrong, this is normal behaviour...you're always adding the
same clonableDataList to your map, and each new iteration, you remove
all the elements from the clonableDataList. Only the last iteration
(with key 2 and values 2,3) are kept.
You need to create a new clonalbeDataList each iteration, so that each
key in you map will have his own clonableDataList.
I suggest that you replace
clonableDataList.removeAll(clonableDataList); with
clonableDataList= new ArrayList<String>();

Regards

Peter
thanks so I was expecting by recycling the same clonableDataList with :
clonableDataList.removeAll(clonableDataList);
to correctly clean the list before adding fresh new elements I will use
instead :
clonableDataList= new ArrayList<String>();
but I still do not understand what this line is actually doing in the first
loop ?
Daniel.

--
Daniel Moyne
(Nulix)---------------------------------------------------------
Distribution : Ubuntu Feisty \\|||// Machine : x86_64
kernel 2.6.20-16-generic / --- \ ATI Radeon X300
KDE 3.5.7 (' o-o ')
----------------------------------------oOO-(_)-OOo--------------------------

It's indeed better to create a new clonableDataList before going to
the next loop and not as first action of a new loop.

public class map {
public static void main(String args[]) {
ArrayList<String>clonableDataList=new ArrayList<String>();
Map<Integer,ArrayList<String>>clonableDataMap= new
HashMap<Integer,ArrayList<String>>();
for (int i=0;i<3;i++) {
clonableDataList.add(Integer.toString(i));
clonableDataList.add(Integer.toString(i+1));
clonableDataMap.put(i,clonableDataList);
clonableDataList=new ArrayList<String>();
}
}
}

so in this case, we don't create a unnecessary clonableDataList in the
first loop.

.

Relevant Pages

  • Re: How to build the => in a statement?
    ... You cannot embed a for loop in an argument list. ... a for loop and map are different beasts. ... to-possibly many transformation applied to the argument list and each ... push @args, $k, $hash; ...
    (comp.lang.perl.misc)
  • Re: question
    ... public static void main(String args[]) { ... the next loop and not as first action of a new loop. ...
    (comp.lang.java.help)
  • Re: Integer as key in HashMap
    ... public static void main(Stringargs) { ... java.util.Map<Long,String> map = ...
    (comp.lang.java.programmer)
  • Re: question
    ... public static void main(String args[]) { ... this one looks much more normal, except that you declared clonableDataList outside the loop, which is too wide a scope. ...
    (comp.lang.java.help)
  • Re: How to build the => in a statement?
    ... You cannot embed a for loop in an argument list. ... a for loop and map are different beasts. ... to-possibly many transformation applied to the argument list and each ... push @args, $k, $hash; ...
    (comp.lang.perl.misc)