面试题：Java中如何使用流式API对集合框架中的对象进行特定属性过滤并求和

Question

假设有一个包含员工信息的Java集合，员工类（Employee）有属性id（整数）、name（字符串）和salary（浮点数）。请使用Java流式API对集合进行操作，过滤出工资大于5000的员工，并计算这些员工的工资总和，给出代码实现。

Answer 1

import java.util.ArrayList;
import java.util.List;

class Employee {
    private int id;
    private String name;
    private float salary;

    public Employee(int id, String name, float salary) {
        this.id = id;
        this.name = name;
        this.salary = salary;
    }

    public float getSalary() {
        return salary;
    }
}

public class Main {
    public static void main(String[] args) {
        List<Employee> employees = new ArrayList<>();
        employees.add(new Employee(1, "Alice", 6000f));
        employees.add(new Employee(2, "Bob", 4000f));
        employees.add(new Employee(3, "Charlie", 7000f));

        float totalSalary = employees.stream()
               .filter(employee -> employee.getSalary() > 5000)
               .mapToFloat(Employee::getSalary)
               .sum();

        System.out.println("工资总和: " + totalSalary);
    }
}