Java – adds multiple bigdecimals to a map

I tried to aggregate multiple bigdecimals from the list At present, I am using two streams, but if possible, I want only one stream I'm not sure how to rewrite the following in an efficient way

BigDecimal totalCharges = tableRowDataList.stream()
            .map(el -> el.getSums().getCharges())
            .reduce(BigDecimal.ZERO,BigDecimal::add);
BigDecimal totalFees = tableRowDataList.stream()
            .map(el -> el.getSums().getFees())
            .reduce(BigDecimal.ZERO,BigDecimal::add);

As you can see, the flows are basically the same, except for the calls to getcharges / getfees

What is the best way to get the result map < string, BigDecimal >? From above? (the key is fees / charges)

Solution

First, you create a class to collect results

Then you do it like BigDecimal, that is, the zero constant and the add () method

public class ChargesAndFees {
    private static final ZERO = new ChargesAndFees(BigDecimal.ZERO,BigDecimal.ZERO);

    private final BigDecimal charges;
    private final BigDecimal fees;

    // constructor and getters

    public ChargesAndFees add(ChargesAndFees that) {
        return new ChargesAndFees(this.charges.add(that.charges),this.fees.add(that.fees));
    }
}

Now you can do flow logic

ChargesAndFees totals = tableRowDataList.stream()
        .map(el -> new ChargesAndFees(el.getSums().getCharges(),el.getSums().getFees()))
        .reduce(ChargesAndFees.ZERO,ChargesAndFees::add);

If you insist, you can convert the value in the total to map