如何才能从Arraylist中获取特定值

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));
}

Answer 1

In Java you can create a sublist ( javadoc ) of a list; eg

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

Notes:

1. 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 .

2. 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.