How can I get only specific values from an Arraylist

Question

I have an ArrayList<Integer> with values (20, 40, 60, 80, 100, 120) Is it possible to only retrieve the position 2-5 only which is 60, 80, 100 and 120? Thanks for any help.

for (DataSnapshot price : priceSnapshot.getChildren()) {
    int pr = price.getValue(Integer.class);
    priceList.add(pr); // size is 61 
}
int total = 0;
List<Integer> totalList = 
            new ArrayList<Integer>(priceList.subList(29, 34));               
for (int i = 0; i < totalList.size(); i++) {
    int to = totalList.get(i);
    total += to;
    txtPrice.setText(String.valueOf(total));
}

Kotlin or Java ?

Mehrdad Pedramfar
– Mehrdad Pedramfar

2019-03-03 07:27:40 +00:00
Commented Mar 3, 2019 at 7:27 — Mehrdad Pedramfar
– Mehrdad Pedramfar, Commented Mar 3, 2019 at 7:27
@MehrdadPedramfar java sir! please help :(

nani10
– nani10

2019-03-03 07:32:06 +00:00
Commented Mar 3, 2019 at 7:32 — nani10
– nani10, Commented Mar 3, 2019 at 7:32
I think below answer works.

Mehrdad Pedramfar
– Mehrdad Pedramfar

2019-03-03 07:34:59 +00:00
Commented Mar 3, 2019 at 7:34 — Mehrdad Pedramfar
– Mehrdad Pedramfar, Commented Mar 3, 2019 at 7:34

Stephen C · Accepted Answer · 2019-03-03 07:50:44Z

6

In Java you can create a sublist (javadoc) of a list; e.g.

List<Integer> list = ...
List<Integer> sublist = list.sublist(2, 6);

Notes:

The the upper bound is exclusive, so that to get the list element containing 120 we must specify 6 as the upper bound, not 5.
The resulting sublist is "backed" by the original list. Therefore:
- there is no copying involved in creating the sublist, and
- changes to the sublist will modify the corresponding positions in the original list.

answered Mar 3, 2019 at 7:50

Stephen C

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18 Comments

nani10 Over a year ago

Hi stephen the parameters of sublist are fromIndex and toIndex will the 2 became 0 index and 6 into 4? I'm a bit confused or still oni the same position?

Stephen C Over a year ago

The sublist elements are numbered from zero, as you observed. Element 2 of the old list is element 0 of the sublist, etcetera. It is done this way to conform to the List API ... which specifies that the first element of a List is at position 0.

nani10 Over a year ago

Hey stephen I have an arraylist that has a size of 61 I only want to get index 29-34 I'm having an error IndexOutOfBoundsException I don't get why? but if I use subList(29, list.size()) No error please help

Stephen C Over a year ago

You need to explain clearly 1) how you are calling sublist and 2) where / how you are getting the exception. (My guess is that you didn't comprehend my note 1.

nani10 Over a year ago

I'm still confused I don't get it. I edited my post can you check? Why is it not working

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