Sum of array list using class with multiple elements java

Question

I have a class like this

public class SellableItems {
    private int id;
    private String name;
    private double price;

    public SellableItems() {
    }

    }
    // getters and setters here
}

Now lets say I have created some objects and put them into an ArrayList, which looks like this

List<SellableItems> table1 = Main.readFromTable1();

Then goes my question. How do calculate the sum (the price) of the ArrayList?

Just a note, it's the recommended format to not start variable names with capital letters as you do with Table1. As you can see, even the SO thinks it's a type and is highlighting it teal. — xtratic
– xtratic, Commented Apr 15, 2018 at 19:44
Yes, you are absolutely right. I have updated my question, thanks! — Peter Holdensgaard
– Peter Holdensgaard, Commented Apr 30, 2020 at 22:17

Georg Plaz · Accepted Answer · 2018-04-15 21:12:48Z

2

If your List is a list of Integers you can use something like:

int sum = 0;
for (int ListItm : DataList) {
    sum += ListItm;
}

Otherwise apply necessary adaptations.

edited Apr 15, 2018 at 21:12

Georg Plaz

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answered Apr 15, 2018 at 19:47

AmerMohamed

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Comments

Ousmane D. · Accepted Answer · 2018-04-15 19:36:33Z

1

You'll need to reduce the list to a double value, to do so, you have to iterate over the Table1 and in each iteration add the price value to the sum variable:

double sum = 0d;
for(SellAbleItems s : Table1) 
     sum += s.getPrice();

answered Apr 15, 2018 at 19:36

Ousmane D.

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2 Comments

Peter Holdensgaard Over a year ago

So this is just a foreach loop and adding all the entries together to the double sum?

Ousmane D. Over a year ago

@PeterHoldensgaard yes.

Georg Plaz · Accepted Answer · 2018-04-15 21:17:37Z

1

If you are using Java 8, you can do it very easily with streams:

List<SellAbleItems> table1 = Main.readFromTable1();

double sum = table1.stream().mapToDouble(e -> e.getPrice()).sum();
// use your sum

edited Apr 15, 2018 at 21:17

Georg Plaz

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answered Apr 15, 2018 at 19:31

Schidu Luca

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2 Comments

Georg Plaz Over a year ago

@PeterHoldensgaard please consider accepting this answer then. It is 1:1 the same as the one you accepted but it was posted an hour earlier

Peter Holdensgaard Over a year ago

Works like a charm, thanks! Assuming that I did this using a string as sum, could I then print out all the names from table1?

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