How do I call .get() on a 2d ArrayList

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I have a 2d ArrayList

ArrayList<ArrayList<String>> list = new ArrayList<ArrayList<String>>();

I want to get the item at say (0,0).

I'm looking for something like:



You must use


since you are not using a real 2-dimensional List but a List of Lists.

2D ArrayList in java, How does the 2D ArrayList work? element of the 2D list, returns an ArrayList, which you must further call get() on to get the element you want. I have a 2D ArrayList and I want to replace one of the elements with something else by using the set method. According to the Java API: set(int index, E Element) is the constructor. How do I inp

As follows

String value = list.get(0).get(0);

Multi Dimensional ArrayList in Java, Learn how to create and work with multidimensional ArrayLists in Java. Integer endVertex = graph.get(i).get(j);. System.out.printf( "Vertex %d  ArrayList HashMap to ArrayList Sort HashMap Iterate HashMap Internal Working of HashMap Hashtable Vs HashMap HashMap Vs HashSet Comparable Comparator Comparator Vs Comparable Multithreading Thread Process vs thread Join Daemon thread Sleep Can we start a thread twice in java Can we call run() method directly to start a new thread wait, notify

Java doesn't have 2d lists (or arrays, for that matter). Use something like this:


Note that arrays have a similar issue. You do not do this:

array[0,0]  // WRONG! This isn't Fortran!

Instead you do this:


Multidimensional Collections in Java, Below is implementation of Multidimensional ArrayList in Java : filter_none. edit static List create2DArrayList() x.get( 0 ).add( 0 , 3 ); x.get( 1 ).add( 0 , 366 );. Hi, I'm having trouble adding objects to a 2D ArrayList, and am also a little confused about the different ways of declaring and initializing 2D ArrayLists and their contents. I am familiar with this way of declaring a 2D list:

It being List of List, you try :

String val = list.get(0).get(0);

Array of ArrayList in Java, super and super() in Java with Examples · In Java, Can we call the main() method of a class from another class? We often come across 2D arrays where most of the part in the array is empty. Here we use ArrayList since the length is unknown. al[i].size() will give the size of the System.out.print(al[i].get(j) + " " );. What you have to remember is that a 2D array is just an array of arrays. ie each element in your array is an array. So to convert it to an ArrayList you take the sub-array in each element, convert it to an ArrayList and add that to you main ArrayList. Sounds more confusing than it is.

This is a program to traverse the 2D-ArrayList. In this program instead of LineX your can get item in the list (i , j ) :-)


Scanner scan = new Scanner(;  
int no_of_rows = scan.nextInt();         //Number of rows 
int no_of_columns = scan.nextInt();      //Number of columns 
ArrayList<ArrayList<String>> list = new ArrayList<>();
for (int i = 0; i < no_of_rows; i++) {      
    list.add(new ArrayList<>());      //For every instance of row create an Arraylist
    for (int j = 0; j < no_of_columns; j++) {
        list.get(i).add(;        //Specify values for each indices
//ArrayList Travesal
for (int i = 0; i < list.size(); i++) {
    for (int j = 0; j < list.get(i).size(); j++) {
        System.out.print(list.get(i).get(j)+" ");   //LineX


2 3 
1 2 3 4 5 6 
1 2 3 
4 5 6

2d Arraylist java example, //Let's retrieve element from the arraylist2D. System.out.println("2nd element in list3 : "  Yes, of course, you can pick ArrayList from an ArrayList. In order to do this you can follow these 2 steps: Initialize and declare 2D ArrayList; As per your question, you have 10 rows (i = 10) and 500 columns (j=500).

2D Array Length, When calling the length of a column, we pinpoint the row before using .length . The program above checks to see how many columns the first row of the 2D array​  Part 2: Next we can call add() with one argument—this appends to the end of the ArrayList. ArrayList add, insert. Part 3: We call size(). This returns the number of elements in the collection (here it is 3). Part 4: We loop over each index with for, and call get. Finally we invoke get(), which receives the index of the element to access.

How to access the elements of a 2 dimensional ArrayList (Java in , I have a class say XYZ which contains a method getSFInGroups() and this method A 2D ArrayList isn't a built-in concept in Java like a 2D array is. A 2D String groupName = (String) outer.get( 0 ); Contact Us | advertise |. Teams. Q&A for Work. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

adding objects to a 2D ArrayList (Java in General forum at Coderanch), But I don't get how you then elements to the ArrayLists within the list (i.e to the inner ArrayList), for example to the List at arr[2][3] specifically, or  Note: The ArrayList only stores objects so although the above lines appear to add int values to ArrayList the are automatically changed to Integer objects as they are appended to the ArrayList. A standard array can be used to populate an ArrayList by converted it to a List collection using the Arrays.asList method and adding it to the ArrayList