CODEWITHSUNDEEP
javaarraylistcollections
Rakesh B
Rakesh B

Reputation: 47

How to store/add list elements in Array-list in the below format?

How to store/add list elements in Array-list in the below format?

x.get(0)->[1,2,3,4],
x.get(1)->([5,6,7,8],
x.get(2)->[9,10,11,12],
x.get(3)->[13,14,15,16]

I'm getting a sequence of numbers and want to separate them with a list. When i use x.add(), that is adding all elements to a single list in sequence order.

Upvotes: 0

Views: 979

Answers (2)

dut gurung
dut gurung

Reputation: 216

By this way you can add list(ArrayList) into ArrayList.

//Adding `ArrayList` into `ArrayList`

ArrayList<ArrayList<Integer>> list = new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> innerList = new ArrayList<Integer>();

//adding element to innerlist 
innerList.add(10);
innerList.add(20);
...

//adding innerList into list

list.add(innerList);

if you are getting a sequence of number as : 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16.

Then below code can help you in preparing a list and adding into ArrayList.

public  ArrayList<ArrayList<Integer>> mainlist = new ArrayList<ArrayList<Integer>>();
public void prepareList() {
        ArrayList<Integer> innerList = new ArrayList<Integer>();
        for (int i = 1; i <= 16; i++) {
            innerList.add(i);
            if (i % 4 == 0) {
                mainlist.add(innerList);
                innerList = new ArrayList();
            }
        }
    }

Upvotes: 1

brso05
brso05

Reputation: 13232

You could do something like this an arraylist of arraylists:

ArrayList<ArrayList<Integer>> arrayList = new ArrayList<ArrayList<Integer>>();

ArrayList<Integer> tempArrayList = new ArrayList<Integer>();

tempArrayList.add(1);
tempArrayList.add(2);
tempArrayList.add(3);
tempArrayList.add(4);
arrayList.add(tempArrayList);

System.out.println(arrayList.get(0).get(0));
System.out.println(arrayList.get(0).get(1));

tempArrayList = new ArrayList<Integer>();

tempArrayList.add(5);
tempArrayList.add(6);
tempArrayList.add(7);
tempArrayList.add(8);
arrayList.add(tempArrayList);

System.out.println(arrayList.get(1).get(0));
System.out.println(arrayList.get(1).get(1));

etc...

If you have a fixed amount of numbers for each list you could do an ArrayList of int[] arrays...

Upvotes: 1

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