JavaCollectors.summarizingDouble统计浮点数方法

import java.util.*;
import java.util.stream.Collectors;

public class DoubleSummaryExample {
    public static void main(String[] args) {
        List prices = Arrays.asList(19.9, 25.5, 30.0, 12.8, 45.6);

        DoubleSummaryStatistics stats = prices.stream()
            .collect(Collectors.summarizingDouble(Double::doubleValue));

        System.out.println("数量: " + stats.getCount());
        System.out.println("总和: " + stats.getSum());
        System.out.println("最小值: " + stats.getMin());
        System.out.println("最大值: " + stats.getMax());
        System.out.println("平均值: " + stats.getAverage());
    }
}

数量: 5
总和: 133.8
最小值: 12.8
最大值: 45.6
平均值: 26.76

class Product {
    private String name;
    private double price;

    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }

    public double getPrice() {
        return price;
    }
}

// 使用示例
List products = Arrays.asList(
    new Product("A", 10.0),
    new Product("B", 20.5),
    new Product("C", 15.3)
);

DoubleSummaryStatistics stats = products.stream()
    .collect(Collectors.summarizingDouble(Product::getPrice));