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

Question

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:

list.get(0,0)

Thanks!

Answer 1

You must use

list.get(0).get(0)

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

Answer 2

如下

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

Answer 3

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

list.get(0).get(0)

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

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

Instead you do this:

array[0][0]

Answer 4

它是列表列表，您可以尝试：

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

Answer 5

This is a program to traverse the 2D-ArrayList. In this program instead of your can get item in the list (i , j ) （i，j） 获得项目而不是

PROGRAM:

Scanner scan = new Scanner(System.in);  
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(scan.next());        //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
    }
    System.out.println();
}

OUTPUT:

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