stream()中计算BigDecimal

实体

public class ApAccountBegin {
    //数量
    private BigDecimal beginQuantity;
    //金额
    private BigDecimal beginBalance;
    //汇率
    private BigDecimal rate;

    public BigDecimal getBeginQuantity() {
        return beginQuantity;
    }

    public void setBeginQuantity(BigDecimal beginQuantity) {
        this.beginQuantity = beginQuantity;
    }

    public BigDecimal getBeginBalance() {
        return beginBalance;
    }

    public void setBeginBalance(BigDecimal beginBalance) {
        this.beginBalance = beginBalance;
    }

    public BigDecimal getRate() {
        return rate;
    }

    public void setRate(BigDecimal rate) {
        this.rate = rate;
    }
}

public static void main(String[] args) {
        BigDecimal bigDecimal = new BigDecimal("20");

        ArrayList<ApAccountBegin> list = new ArrayList<>(10);
        ApAccountBegin apAccountBegin = new ApAccountBegin();
        apAccountBegin.setBeginQuantity(bigDecimal);
        apAccountBegin.setBeginBalance(bigDecimal);
        apAccountBegin.setRate(new BigDecimal("1.00"));
        for(int i=1;i<=10;i++){
            list.add(apAccountBegin);
        }
        //累加求和计算数量
        BigDecimal reduce = list.stream().map(ApAccountBegin::getBeginQuantity).reduce(BigDecimal.ZERO,BigDecimal::add);
        //累加求和计算金额 汇率*金额
        BigDecimal reduce1 = list.stream().map(a->a.getBeginBalance().multiply(a.getRate())).reduce(BigDecimal.ZERO, BigDecimal::add);
        System.out.println(reduce);
        System.out.println(reduce1);
        //另一种写法
        //System.out.println(list.stream().map(a->a.getBeginBalance().multiply(a.getRate())).reduce((x,y)->x.add(y)).get());
    }