How to add one arraylist to other arraylist in android?

Question

I have created 3 arraylists and stored data in it. I need to pass one single arraydata to other page and so I have added my individual arrays to the main array. But when I added one array to other the data is not being aded to that array. Here is my code:

static ArrayList<ArrayList<String>> stringList1=new ArrayList<ArrayList<String>>();
static ArrayList<ArrayList<String>> stringList3; 

stringList1 = Mypage.stringList1;

 ArrayList<String> optionlist = new ArrayList<String>();
stringList3 = new ArrayList<ArrayList<String>>();stringList3 = dbAdapter.selectRecordsFromDBList(query2, null); 
 for (int i = 0; i < stringList3.size(); i++) {
    optionlist = stringList3.get(i);
    System.out.print("option list size");
    System.out.print(optionlist.size());
    stringList1.add(optionlist);
    System.out.println("total stringlist1"+stringList1.get(0));

I am getting the stringList1 array values from Mypage and accessing that in new page. In the new page I am trying to add the optionlist array to stringList1 by giving stringList1.add(optionlist) but the data is not adding. Where I went wrong? Please help me regarding this... Thanks in Advance

No iteration required. Read this. stackoverflow.com/a/8666707/2707485 — Ashokchakravarthi Nagarajan
– Ashokchakravarthi Nagarajan, Commented Jul 1, 2015 at 17:14

Sunil Kumar Sahoo · Accepted Answer · 2011-12-29 10:31:49Z

15

Use addAll() It appends all of the elements in the specified ArrayList to the end of this list, in the order that they are returned by the specified Collection's Iterator.

use stringList1.addAll(optionlist); instead of stringList1.add(optionlist);

answered Dec 29, 2011 at 10:31

Sunil Kumar Sahoo

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Comments

Dharmendra · Accepted Answer · 2011-12-29 10:54:50Z

After seeing your code I can guess that you have problem that elements of arrayList is not copy in another arrayList.If this is your issue then change your code like below

static ArrayList<ArrayList<String>> stringList1=new ArrayList<ArrayList<String>>();
static ArrayList<ArrayList<String>> stringList3; 

stringList1 = Mypage.stringList1;

ArrayList<String> optionlist;
stringList3 = new ArrayList<ArrayList<String>>();
stringList3 = dbAdapter.selectRecordsFromDBList(query2, null); 

 for (int i = 0; i < stringList3.size(); i++) {
    optionlist = new ArrayList<String>();
    optionlist = stringList3.get(i);
    System.out.print("option list size");
    System.out.print(optionlist.size());
    stringList1.add(optionlist);
    System.out.println("total stringlist1"+stringList1.get(0));
 }

Lalit Poptani · Accepted Answer · 2011-12-29 10:56:42Z

2

The problem seems that you are initializing your

ArrayList<String> optionlist;

only once that is outside the loop. So, in that case only the first ArrayList gets stored. So, initialized the ArrayList<String> optionlist inside the loop.

ArrayList<String> optionlist;

for (int i = 0; i < stringList3.size(); i++) {
    optionlist = new ArrayList<String>();
    optionlist = stringList3.get(i);
    stringList1.add(optionlist);
 }

edited Dec 29, 2011 at 10:56

answered Dec 29, 2011 at 10:35

Lalit Poptani

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4 Comments

RaagaSudha Over a year ago

Hi thanks for the response..I took a list but even then the same problem..plz help me

Lalit Poptani Over a year ago

I can't get you what you are trying to do actually, so please can you explain more.

RaagaSudha Over a year ago

I am getting values from stringlist1 from page1 to page2 using stringlist1 = page1.stringlist1. Now I need to add my optionlist array which is in page2 to stringList1 arraylist. But the data is not adding to stringlist1.What is the mistake I am doing?

Lalit Poptani Over a year ago

hmmm the problem is you are only initializing your ArrayList only once outside the loop check my edited answer.

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