优化方式（java匿名类）

package com.atguigu.java8;


// Employee员工类
public class Employee {
    private String name;
    private int age;
    private double salary;

    @Override
    public String toString() {
        return "Employee{" +
                "name='" + name + ''' +
                ", age=" + age +
                ", salary=" + salary +
                '}';
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public Employee(String name, int age, double salary) {
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public Employee() {
    }
}

package com.atguigu.java8;

import org.testng.annotations.Test;

import java.util.*;



// 实现方法
public class TestLambda {

    // 原来的匿名内部类
    @Test
    public void test1(){
        Comparator com = new Comparator() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return Integer.compare(o1,o2);
            }
        };
        TreeSet ts = new TreeSet<>(com);
    }

    // Lambda 表达式
    @Test
    public void test2(){
        Comparator com = (x,y) -> Integer.compare(x,y);
        TreeSet ts = new TreeSet<>(com);
    }

    List emplyees = Arrays.asList(
            new Employee("张三",18,1132),
            new Employee("李四",48,1232),
            new Employee("王五",18,3432),
            new Employee("赵六",45,1232)
    );

    // 需求：获取当前公司中员工年龄大于35的员工信息
    @Test
    public void test3(){
        List list = filterEmployees(emplyees);
        for (Employee employee : list) {
            System.out.println(employee);
        }
    }

    public List filterEmployees(List list){
        List emps = new ArrayList<>();

        for (Employee employee : list) {
            if (employee.getAge() >= 35) {
                emps.add(employee);
            }
        }
        return emps;
    }

    // 优化方式一：策略设计模式
    @Test
    public void test4(){
        List list = filterEmployee(emplyees,new FilterEmployeeBySalary());
        for (Employee employee : list){
            System.out.println(employee);
        }

        System.out.println("=============================");

        List list2 = filterEmployee(emplyees,new FilterEmployeeByAge());
        for (Employee employee : list2) {
            System.out.println(employee);
        }
    }

    public List filterEmployee(List list, Mypredicate mp){
        List emps = new ArrayList<>();

        for (Employee employee : list) {
            if (mp.test(employee)){
                emps.add(employee);
            }
        }
        return emps;
    }

    // 优化方二； 匿名内部类
    @Test
    public void test5(){
        List list = filterEmployee(emplyees, new Mypredicate() {
            @Override
            public boolean test(Employee employee) {
                return employee.getSalary() >= 1200;
            }
        });
        for (Employee employee : list) {
            System.out.println(employee);
        }
    }

    // 优化方式三: Lambda 表达式
    @Test
    public void test6(){
        List list = filterEmployee(emplyees,(e) -> e.getSalary() >= 1200);
        list.forEach(System.out::println);
    }

    // 优化方式四；Stream API
    @Test
    public void test7(){
        emplyees.stream()
                .filter((e) -> e.getSalary() >= 1200)
                .limit(2)
                .forEach(System.out::println);
        System.out.println("------------------------------");

        emplyees.stream()
                .map(Employee::getName)
                .forEach(System.out::println);
    }
}

package com.atguigu.java8;

// 实现接口


public interface Mypredicate  {
    public boolean test(T t);
}

// Mypredicate 实现类1
package com.atguigu.java8;

public class FilterEmployeeByAge implements Mypredicate {
    @Override
    public boolean test(Employee employee) {
        return employee.getAge() >= 35;
    }
}

// Mypredicate 实现类2
package com.atguigu.java8;

public class FilterEmployeeBySalary implements  Mypredicate{
    @Override
    public boolean test(Employee employee) {
        return employee.getSalary() >= 400;
    }
}