keeping original Vector intact when modifying it's copy

问题

I want to Copy a Vector containing the following struct and the importance for me is to keep the original Vector intact when i modify the copied one :

public class objet_poid_n {
   public  int Num;
   public double Poid;
                       }

supposing that we have :

Vector original = new Vector();
original = filled((Vector) original); // function fills original with many objet_poid_n elements
Vector destination = new Vector();

I tried :

destination = original ;

and

destination = original.clone();

and

destination.setSize(original.size());
Collections.copy(destination,original);

and

destination.addAll((Vector) original);

and

destination.copyInto((Vector) original);

Unfortunately all of these methods i used gives me always the same problem !! Whatever i modify the destination !!! the original one is modified too !!!!!! any idea please !! it's driving me crazy ! i don't understand why !! now am stuck since 3 days

 Vector copy=new Vector((Vector) allPopulation.get(0));
        for(int j=0;j<100;j++){
            System.out.println("--------------------iteration num :"+(j+1)+"----------------------");
            System.out.println("sol 1 ------->");
            affiche_resultat((Vector) allPopulation.get(0)); \\ affiche_result to print the containing of the vector just for test



            System.out.println("Copy -------->");
            affiche_resultat(copy);

            Vector muted = new Vector();
            muted = mutation(copy);
            System.out.println("Mutated ----------->");
            affiche_resultat(muted);
            System.out.println();}


    }

the mutation function is as follow .. :

private Vector mutation(Vector son1){
      Vector topac = new Vector(); // à remplir par les objet qu'on va supprimer
       // dégager les null                 
     Vector son = new Vector(son1);

        son.removeAll(Collections.singleton(null));
       int j=0,i=0;
      boolean remove = (Math.random() > 0.3) ; // probabilité d'avoir true = 0.7
             for(i=0;i<son.size();i++){
            remove = (Math.random() > 0.3);
                      System.out.println(" remove ="+remove);

            if((remove == true) && (son.get(i) != null)){
            Capaciter_n_objet bin =(Capaciter_n_objet) son.get(i);
            Vector objetlist=bin.n_objet;
            for(j=0;j<objetlist.size();j++)
                     {
                int del =(int) Integer.parseInt(""+objetlist.get(j));
                topac.add(new Integer(del));                    
                        }
           topac.removeAll(Collections.singleton(null));
            //son.removeElementAt(i);
            son.setElementAt(null, i);
            }
            }                     
        son.removeAll(Collections.singleton(null));
        topac.removeAll(Collections.singleton(null));
        Collection noDup = new LinkedHashSet(topac); //remove duplications
        topac.clear();
        topac.addAll(noDup);  
        correctionmutation(son,topac);
             return son;
 }

回答1:

you need to do deep cloning, A simple way is to serialize the vector and desalinize it again. You will get the expected result. Note: Objects in the vector should be serializable

(or)

create a new vector, Then iterate over the existing vector and colne each object in the vector and add to new it to new vector

回答2:

Finally i ve got the solution from one of my friends, lately, i discovered that if we work with a Vector containing some Data Struct or a Class elements, all the kinds of copy that i mentioned above leads always to a shallow copy.
So the solution was to create a copy constructor or function to make a DEEP Copy, the proposed function we have got now is :

 public Vector copi(Vector copy){
        Vector callp=new Vector();
         for(int i=0;i<copy.size();i++){
                copy.removeAll(Collections.singleton(null));
                Capaciter_n_objet cno1=null,cno=(Capaciter_n_objet) copy.get(i);
                cno1=new Capaciter_n_objet();
                cno1.capaiter_rest=cno.capaiter_rest;
                cno1.n_objet= (Vector)  cno.n_objet.clone();
                callp.add(cno1);
            }       
 return callp;           
 }

And thanx for all your suggestion and ideas :)

来源：https://stackoverflow.com/questions/18731950/keeping-original-vector-intact-when-modifying-its-copy

标签

java

netbeans

data-structures

vector

copy