Filter 是过滤器, 也可以当查询方法使用
EmployeeTestCase.java
- package com.example.demo;
- import lombok.extern.log4j.Log4j2;
- import org.junit.Test;
- import java.util.List;
- import java.util.Optional;
- import java.util.stream.Collectors;
- import static org.junit.Assert.assertEquals;
- import static org.junit.Assert.assertTrue;
- @Log4j2
- public class EmployeeTestCase extends BaseTest{
- @Test
- public void filter() {
- // 获取包含 Alex 员工列表
- List<Employee> employeeIs1 = list.stream().filter(e -> e.getName().contains("Alex")).collect(Collectors.toList());
- assertTrue(null != employeeIs1 && employeeIs1.get(0).getId() == 1l);
- // 获取包含 Jacks 名称的首位员工
- Optional<Employee> employeeJaskFirst2 = list.stream().filter(e -> e.getName().contains("Jack")).findFirst();
- assertEquals(employeeJaskFirst2.get().getId(), 3);
- // 获取所有薪酬为 1500 的员工
- List<Employee> employees1350 = list.stream().filter(employee -> employee.getSalary() == 1500).peek(System.out::println).collect(Collectors.toList());
- assertEquals(2, employees1350.size());
- }
- }
BaseTest.java
- package com.example.demo;
- import java.util.Arrays;
- import java.util.List;
- public class BaseTest {
- 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));
- protected static final List<List<Employee>> listFlat = Arrays.asList(
- Arrays.asList(new Employee(1, "Alex", 1000),
- new Employee(2, "Michael", 2000)),
- Arrays.asList(new Employee(3, "Jack", 1500),
- new Employee(4, "Owen", 1500)),
- Arrays.asList(new Employee(5, "Denny", 2000)));
- }
来源: http://www.bubuko.com/infodetail-3303166.html