lambda

Posted 2021-02-08 paytons

 1 public class TestPerson {
 2     List<Person> javaProgrammers = new ArrayList<Person>() {
 3         {
 4             add(new Person("Elsdon", "Jaycob", "Java programmer", "male", 43, 2300));
 5             add(new Person("Tamsen", "Brittany", "Java programmer", "female", 23, 1500));
 6             add(new Person("Floyd", "Donny", "Java programmer", "male", 33, 1800));
 7             add(new Person("Sindy", "Jonie", "Java programmer", "female", 32, 1600));
 8             add(new Person("Vere", "Hervey", "Java programmer", "male", 22, 1200));
 9             add(new Person("Maude", "Jaimie", "Java programmer", "female", 27, 1900));
10             add(new Person("Shawn", "Randall", "Java programmer", "male", 30, 2300));
11             add(new Person("Jayden", "Corrina", "Java programmer", "female", 35, 1700));
12             add(new Person("Palmer", "Dene", "Java programmer", "male", 33, 2300));
13             add(new Person("Addison", "Pam", "Java programmer", "female", 34, 10));
14         }
15     };
16 
17     //遍历
18     @Test
19     public void ergodic() {
20         javaProgrammers.forEach(person -> System.out.println(person.getFirstName()));
21     }
22 
23     //给所有的程序员加薪5%
24     @Test
25     public void addSalary() {
26         javaProgrammers.forEach(person -> person.setSalary(person.getSalary() + person.getSalary() * 5 / 100));
27         javaProgrammers.forEach(person -> System.out.println(person.getFirstName() + "工资是：" + person.getSalary()));
28     }
29 
30     @Test
31     public void addSalary2() {
32         Consumer<Person> consumer = person -> {
33             person.setSalary(person.getSalary() + person.getSalary() * 5 / 100);
34         };
35         javaProgrammers.forEach(consumer);
36         javaProgrammers.forEach(person -> System.out.println(person.getFirstName() + "工资是：" + person.getSalary()));
37     }
38 
39     //过滤----工资大于2000的员工
40     @Test
41     public void filterDemo() {
42         javaProgrammers.stream().filter(person -> person.getSalary() >= 2000).
43                 forEach(person -> System.out.println(person.getFirstName() + "工资是：" + person.getSalary()));
44     }
45 
46     //自定义过滤器
47     @Test
48     public void selfDefineFilter() {
49         Predicate<Person> predicate = person -> person.getSalary() >= 2000;
50         Predicate<Person> predicate1 = person -> person.getAge() >= 40;
51         javaProgrammers.stream().filter(predicate).filter(predicate1).
52                 forEach(person -> System.out.println(person.getFirstName() + "年龄是" + person.getAge() + "工资是："
53                         + person.getSalary()));
54     }
55 
56     //限制打印的个数
57     @Test
58     public void limitDemo() {
59         javaProgrammers.stream().filter(person -> person.getGender().equals("female")).limit(3)
60                 .forEach(person -> System.out.println(person.getFirstName() + "性别是" + person.getGender()));
61     }
62 
63     //工资最高的前3位,如果工资相同按年龄排序,并放在一个集合中
64     @Test
65     public void limit3Demo() {
66         List<Person> collect = javaProgrammers.stream().sorted((p1, p2) -> (
67                 p2.getSalary() - p1.getSalary() == 0 ? p2.getAge() - p1.getAge() : p2.getSalary() - p1.getSalary()
68         )).limit(3).collect(Collectors.toList());
69         System.out.println(Arrays.deepToString(collect.toArray()));
70     }
71 
72     //打印工资最高和最小的
73     @Test
74     public void minAndMaxSarlay() {
75         Person person = javaProgrammers.stream().min((p1, p2) -> (p1.getSalary() - p2.getSalary())).get();
76         System.out.println(person);
77         Person person1 = javaProgrammers.stream().max((p1, p2) -> (p1.getSalary() - p2.getSalary())).get();
78         System.out.println(person1);
79     }