如何在for循环中从arraylist获取所有数据总和？

Question

This is the code:

ArrayList<DailyChallengesModelFinal> dailyList = new ArrayList<>();
    int selectedItems = position;
                    Log.d("dbKEY", String.valueOf(exDBKey));
                    int sum = 0;
                    for (int i = selectedItems; i <=0; i++) {


                        int points = dailyList.get(position).getPoints();
                        sum = sum + points;     }

I'm not getting the desired result.

What I wanna get is for example the array has 50,80,and 60 then it should add the values from the array.

Answer 1

try this code

  int sum = 0;
    for(int i = 0; i <=dailyList.size(); i++) {
        dailyExerciseID = dailyList.get(i).getDcExerciseId();
        dailyExerciseName = dailyList.get(i).getDcexerciseName();
        points = dailyList.get(i).getPoints();
        sum = sum + points;
    }

Answer 2

Look at this:

for (int i = selectedItems; i <=0; i++) {

The starting value of i is selectedItems which is a positive number I suppose.
The limit you set for the loop to stop is i <=0 while you increase i by i++ .
This for loop will never execute.
Change the starting point and the condition to stop.
If you want to iterate through the whole list then:

for (int i = 0; i < dailyList.size(); i++) {

If you want to iterate through the first selectedItems items then:

for (int i = 0; i < selectedItems; i++) {

Answer 3

This will do your job:

    ArrayList<DailyChallengesModelFinal> dailyList = new ArrayList<>();
    int selectedItems = position;
                    Log.d("dbKEY", String.valueOf(exDBKey));
                    int sum = 0;
                    for (int i = selectedItems; i > 0; i--) 
                    {
                        int points = dailyList.get(i).getPoints();
                        sum += points;     
                    }

Answer 4

dailyList.subList(position, dailyList.size()).stream().map(DailyChallengesModelFinal::getPoint).reduce((p1, p2) -> p1 + p2).orElse(0);

Answer 5

I have updated your code. Please check it.

               int sum = 0;
             for (int i = 0; i <dailyList.size(); i++) {

                dailyExerciseID = dailyList.get(position).getDcExerciseId();
                dailyExerciseName = dailyList.get(position).getDcexerciseName();
                sum = sum + dailyList.get(position).getPoints();

              }