Nested ArrayList

Question

I have a 3 level nested arrayList as follows:

   ArrayList<String> rowContents = new ArrayList();
   ArrayList<ArrayList<String>> rows;
   ArrayList<ArrayList<ArrayList<String>>> page;

In the code, within different loops, the arrayLists will be populated as follows:

    rowContents.add("some content");
    rows.add(rowContents);
    page.add(rows);

Is it okay to use 3 level nested arrayLists like this? Or, is there a better approach?

"is there a better approach" For what? What is your actual problem? — user1907906
– user1907906, Commented Dec 19, 2013 at 11:35
When you have 3 nested ArrayLists, it might be a sign of a bad design. — Maroun
– Maroun, Commented Dec 19, 2013 at 11:35
@LutzHorn - better approach for handling (or revising) a nested arrayList design. — janenz00
– janenz00, Commented Dec 19, 2013 at 11:42

Philipp Sander · Accepted Answer · 2013-12-19 11:39:47Z

11

I suggest to create classes for page and rows.

Internaly they can hold their children in a list:

public class Row {
    List<String> rowContent;
    Page parent;

    //...
}



public class Page {
    List<Row> rows;

    //...
}

edited Dec 19, 2013 at 11:39

answered Dec 19, 2013 at 11:37

Philipp Sander

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1 Comment

Vineet Singla Over a year ago

+1 for creating classes.. Wont you think it is tree like structure.. good to craate tree object

Knoobie · Accepted Answer · 2013-12-19 11:43:23Z

1

How about some classes for page and rows? It's easier to maintain!

public class Page{

private List<Row> rows = new ArrayList<Row>();

}

public class Row{

/* do some crazy stuff in it*/

}


/* all pages*/
List<Page> pages = new ArrayList<Page>();

for(Row row: pages.getRows()){
  /* do some crazy stuff with the content of the row */
}

answered Dec 19, 2013 at 11:43

Knoobie

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