java8使用filter()取出自己所需数据

package com.it.pojo; 

import java.util.Comparator;

import java.util.Objects;

@Data

@NoArgsConstructor

@ToString

public class Person {

    private String name;

    private Integer age;

}

package com.it.test;

import java.util.ArrayList;

import java.util.List;

import com.it.pojo.Person; 

import java.util.Comparator;

import java.util.stream.Collectors;

public class StreamTest {

     public static void main(String[] args) {

         Person person1 = new Person();

         person1.setAge( 21 );

         person1.setName( "21" );

         Person person2 = new Person();

         person2.setAge( 19 );

         person2.setName( "19" );

         Person person3 = new Person();

         person3.setAge( 19 );

         person3.setName( "20" );

         Person person4 = new Person();

         person4.setAge( 20 );

         person4.setName( "20" );

         Person person5 = new Person();

         person5.setAge( 19 );

         person5.setName( "18" );

         List<Person> people = new ArrayList<>();

         people.add(person1);

         people.add(person2);

         people.add(person3);

         people.add(person4);

         people.add(person5);

         List<Person> collect1 = people.stream().filter((person) -> {

             return person.getName().equals( "18" );  //取姓名是18的Person数据

         }).collect(Collectors.toList());

         System.out.println(collect1);

          List<Person> collect2 = people.stream().filter((person) -> {

             return person.getAge().intValue()== 19 && person.getName().equals( "19" ); 

         }).collect(Collectors.toList());

         System.out.println(collect2);

           List<Person> collect = people.stream().filter(person ->

             person.getName().equals( "181" )   //测试不满足条件的list集合会是什么样的

         ).collect(Collectors.toList());

         System.out.println(collect);    //集合size==0

         if (collect.size()== 0 ){

             System.out.println( "nihao" );

         }

    }

}