package com.example.demo;

import lombok.extern.log4j.Log4j2;

import org.junit.Test;

import java.util.DoubleSummaryStatistics;

import java.util.stream.Collectors;

@Log4j2

public class EmployeeTestCase extends BaseTestCase {

    @Test

    public void statis(){

        //实现方式一

        DoubleSummaryStatistics statistics = list.stream().collect(Collectors.summarizingDouble(Employee::getSalary));

        //实现方式二

        DoubleSummaryStatistics statistics1 = list.stream().mapToDouble(Employee::getSalary) .summaryStatistics();

    }

}

package com.example.demo;

import java.util.Arrays;

import java.util.List;

public class BaseTestCase {

    protected static final List<Employee> list = Arrays.asList(

            new Employee(1, "Alex", 1000),

            new Employee(2, "Michael", 2000),

            new Employee(3, "Jack", 1500),

            new Employee(4, "Owen", 1500),

            new Employee(5, "Denny", 2000));

}