Java8 新特性 Lambda学习

import java.util.ArrayList;import java.util.Collections;import java.util.IntSummaryStatistics;import java.util.List;import java.util.stream.Collectors;public class TestLambda{        public static void main(String[] args)    {        List<Employee> employees = new ArrayList<Employee>();        employees.add(new Employee("张三", "男", 25));        employees.add(new Employee("李四", "女", 24));        employees.add(new Employee("王五", "女", 23));        employees.add(new Employee("周六", "男", 22));        employees.add(new Employee("孙七", "女", 21));        employees.add(new Employee("刘八", "男", 20));        // ---------------------------------------------- 输出employees        System.out.println("##############输出employees##############");        employees.forEach(e -> System.out.println(e));        System.out.println("----------------------------------------------");        employees.stream().forEach(e -> System.out.println(e));        // ---------------------------------------------- 按年龄排序        System.out.println("##############按年龄排序##############");        Collections.sort(employees, (e1, e2) -> e1.getAge() - e2.getAge());        employees.forEach(e -> System.out.println(e));        System.out.println("----------------------------------------------");        employees.stream().sorted((e1, e2) -> e1.getAge() - e2.getAge()).forEach(e -> System.out.println(e));        // ---------------------------------------------- 打印年龄最大的女员工        System.out.println("##############打印年龄最大的女员工##############");        Employee maxAgeFemaleEmployee =            employees.stream().filter(e -> "女".equals(e.getSex())).max((e1, e2) -> e1.getAge() - e2.getAge()).get();        System.out.println(maxAgeFemaleEmployee);        // ---------------------------------------------- 打印出年龄最大的2名男员工        System.out.println("##############打印出年龄最大的2名男员工##############");        employees.stream()            .filter(e -> "男".equals(e.getSex()))            .sorted((e1, e2) -> e2.getAge() - e1.getAge())            .limit(2)            .forEach(e -> System.out.println(e));        // ---------------------------------------------- 打印出所有男员工的姓名,使用 ,分隔        System.out.println("##############打印出所有男员工的姓名,使用 ,分隔##############");        String maleEmployeesNames = employees.stream().map(e -> e.getName()).collect(Collectors.joining(","));        System.out.println(maleEmployeesNames);                // ---------------------------------------------- 统计信息        System.out.println("##############统计信息##############");        IntSummaryStatistics stat = employees.stream().mapToInt(Employee::getAge).summaryStatistics();        System.out.println("员工总数：" + stat.getCount());        System.out.println("最高年龄：" + stat.getMax());        System.out.println("最小年龄：" + stat.getMin());        System.out.println("平均年龄：" + stat.getAverage());    }}

 

public class Employee{    private String name;        private String sex;        private int age;        public Employee(String name, String sex, int age)    {        super();        this.name = name;        this.sex = sex;        this.age = age;    }        public String getName()    {        return name;    }        public String getSex()    {        return sex;    }        public int getAge()    {        return age;    }        @Override    public String toString()    {        StringBuilder builder = new StringBuilder();        builder.append("Employee {name=")            .append(name)            .append(", sex=")            .append(sex)            .append(", age=")            .append(age)            .append("}");        return builder.toString();    }}

转载于:https://www.cnblogs.com/zhc-hnust/p/5958054.html