526互联

2个List集合取差集

发布时间 2023-08-13 17:25:30作者: 消失的那两年

定义了一个Student实体类

/**
 * @author 王立朝
 * @date 2023/3/21
 * @description:
 */
public class Student {
    private String id;
    private String name;
    private Integer age;

    private String ispUserId;

    @Override
    public String toString() {
        return "Student{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", ispUserId='" + ispUserId + '\'' +
                '}';
    }

    public Student() {
    }

    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public Student(String name, Integer age, String ispUserId) {
        this.name = name;
        this.age = age;
        this.ispUserId = ispUserId;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

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

    public String getIspUserId() {
        return ispUserId;
    }

    public void setIspUserId(String ispUserId) {
        this.ispUserId = ispUserId;
    }
}

需求：

// 第三方服务数据集合（其中，删除了 IspUserId == 0005 的数据，但是 数据库集合中（dbList）中没有删除IspUserId == 0005 的数据
// 需要找出 第三方已经删除掉的数据，但是数据库中没有被删除的数据的集合）

import com.wlc.vo.Student;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

/**
 * @author 王立朝
 * @date 2023/7/27
 * @description:
 */
public class MyStreamTest {
	public static void main(String[] args) {
		MyStreamTest streamTest = new MyStreamTest();
		streamTest.test02();
	}

	/**
	 *
	 *    List<BaiduHotSearchVo> collect = baiduHotSearchVoList.stream().filter(a ->
	 *                 !baiduHotSearchHistoryVoList.stream()
	 *                         .map(b -> b.getTitle()).collect(Collectors.toList())
	 *                         .contains(a.getTitle())
	 *
	 *         ).collect(Collectors.toList());
	 *
	 *
	 */
	public void test02(){
		// 第三方服务数据集合（其中，删除了 IspUserId == 0005 的数据，但是 数据库集合中（dbList）中没有删除IspUserId == 0005 的数据
		// 需要找出 第三方已经删除掉的数据，但是数据库中没有被删除的数据的集合）
		List<Student> serviceList = getServiceList();
		List<Student> dbList = getDbList();
		List<Student> collect1 = dbList.stream().filter(e -> !serviceList.stream().map(b -> b.getIspUserId()).collect(Collectors.toList()).contains(e.getIspUserId())).collect(Collectors.toList());
		System.out.println("collect1 = " + collect1);
		List<String> collect = collect1.stream().map(e -> e.getIspUserId()).collect(Collectors.toList());
		System.out.println("collect = " + collect);
		/*List<Student> collect = serviceList.stream().filter(e -> !dbList.stream()
						.map(b -> b.getIspUserId()).collect(Collectors.toList()).contains(e.getIspUserId()))
				.collect(Collectors.toList());
		System.out.println("collect = " + collect);*/

	}

	/**
	 * 第三方的List集合
	 * @return
	 */
	public List<Student> getServiceList(){
		List<Student> list1 = new ArrayList<>();
		Student student1 = new Student();
		student1.setId("1");
		student1.setName("张三");
		student1.setIspUserId("0001");

		Student student2 = new Student();
		student2.setId("2");
		student2.setName("王五");
		student2.setIspUserId("0002");

		/*Student student3 = new Student();
		student3.setId("3");
		student3.setName("赵六");
		student3.setIspUserId("0003");*/

		Student student4 = new Student();
		student4.setId("4");
		student4.setIspUserId("0004");

		/*Student student5 = new Student();
		student5.setId("5");
		student5.setName("六六");
		student5.setIspUserId("0005");*/
		list1.add(student1);
		list1.add(student2);
		/*list1.add(student3);*/
		list1.add(student4);
		/*list1.add(student5);*/
		return list1;
	}

	/**
	 * 数据库中的List集合
	 * @return
	 */
	public List<Student> getDbList(){
		List<Student> list1 = new ArrayList<>();
		Student student1 = new Student();
		student1.setId("1");
		student1.setName("张三");
		student1.setIspUserId("0001");

		Student student2 = new Student();
		student2.setId("2");
		student2.setName("王五");
		student2.setIspUserId("0002");

		Student student3 = new Student();
		student3.setId("3");
		student3.setName("赵六");
		student3.setIspUserId("0003");

		Student student4 = new Student();
		student4.setId("4");
		student4.setName("田七");
		student4.setIspUserId("0004");

		Student student5 = new Student();
		student5.setId("5");
		student5.setName("六六");
		student5.setIspUserId("0005");
		list1.add(student1);
		list1.add(student2);
		list1.add(student3);
		list1.add(student4);
		list1.add(student5);
		return list1;
	}

}

测试结果：

collect1 = [Student{id='3', name='赵六', age=null, ispUserId='0003'}, Student{id='5', name='六六', age=null, ispUserId='0005'}]
collect = [0003, 0005]