Adding ArrayList into Another ArrayList

Question

I have an ArrayList in my program and some part of the program I'm parsin an soap object and every item is one tempArraylist.After the item iteration is finished I'm adding this ArrayList into another Arraylist my problem is it's not adding the content it is adding the reference of the tempArray.How can I add the value of array not reference of it.

Here is my code.

for (int i = 0; i < count; i++) 
   {
       tempContents.clear();

       Log.i(TAG , String.valueOf(count));

       Object property = response2.getProperty(i);


       if (property instanceof SoapObject)
       {
           SoapObject category_list = (SoapObject) property;



           for(int j = 0 ; j<tags.size() ; j++)
           {
               if(category_list.getProperty(tags.get(j)).toString().contains("Resim"))
               {
                   String tempResim = "htttp://www.balikesir.bel.tr/";
                   tempResim += category_list.getProperty(tags.get(j)).toString();
                   tempContents.add(tempResim);  
               }
               else
               {
                   if(category_list.getProperty(tags.get(j)).toString().equals("anyType{}"))
                   {continue;}
                   tempContents.add(category_list.getProperty(tags.get(j)).toString());

               }
           }
           for(int k = 0 ;k < tempContents.size() ; k++ )
               Log.i("For ici 5 minare",tempContents.get(k));
           Log.i("For disi 4 minare","Asdas asdas");
           contents.add(tempContents);
       }

    }

Please have a look at my answer Important Notes part, for getting more clearity.It will help you — Prateek
– Prateek, Commented Feb 3, 2014 at 13:49

Prateek · Accepted Answer · 2014-02-03 13:48:43Z

Use public boolean addAll(Collection<? extends E> c)

contents.addAll(tempContents);

What addAll(Collection c) does ?

From Java docs,

/**
 * Appends all of the elements in the specified collection to the end of
 * this list, in the order that they are returned by the
 * specified collection's Iterator.  The behavior of this operation is
 * undefined if the specified collection is modified while the operation
 * is in progress.  (This implies that the behavior of this call is
 * undefined if the specified collection is this list, and this
 * list is nonempty.)
 *
 * @param c collection containing elements to be added to this list
 * @return <tt>true</tt> if this list changed as a result of the call
 * @throws NullPointerException if the specified collection is null
 */

EXAMPLE

List test = new ArrayList();
test.add("A");
test.add("B");
test.add("C");
test.add("D");
List test1 = new ArrayList();
test1.add("E");
test1.add("F");
test1.add("G");
test1.add("H");
test1.add("I");

//test.add(new ArrayList(test1));  // Dont use this if u want to add content and not entire arrayList as its output will be [A, B, C, D, [E, F, G, H, I]]



test.addAll(test1);
System.out.println(test);

Output

[A, B, C, D, E, F, G, H, I]

Important Notes

1. Use test.add(test1.clone()); Only if test1 reference is of ArrayList type and not of List type as List does not implements Cloneable Interface

2. Dont Use test.add(new ArrayList(test1)); ,if u want to add content and not entire arrayList as its output will be [A, B, C, D, [E, F, G, H, I]].

FD_ · Accepted Answer · 2014-02-03 13:28:15Z

2

Use something like this instead:

contents.add(new ArrayList(tempContents));

Alternative:

contents.add(tempContents.clone());

Alternative 2:

contents.addAll(tempContents);

Choose 1 or 2 for inserting the whole ArrayList as one item and 3 for adding all the items as separate items to the list.

edited Feb 3, 2014 at 13:28

answered Feb 3, 2014 at 13:21

FD_

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6 Comments

Esat IBIS Over a year ago

contents.add(tempContents.clone()); this one is not working on me but new ArrayList is working.

Esat IBIS Over a year ago

10 min rules.But I will.

Prateek Over a year ago

Output of contents.add and contents.addAll will be different.One adds list and other add elements of list

FD_ Over a year ago

Exactly. And that's what I say in my last two lines. So please remove your downvote. I upvoted yours in return ;)

Prateek Over a year ago

there is nothing like a clone() method for List reference type if reference is of type ArrayList then only clone will work

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