Lambda Expression - Function

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Function

Function是从T到R的一元函数映射，将参数T传递给一个函数，返回R，即 R = Function(T)

  

Demo

FunctionTest.java

 1 package org.fool.java8;
 2 
 3 import java.util.function.BiFunction;
 4 import java.util.function.Function;
 5 import java.util.function.IntFunction;
 6 
 7 public class FunctionTest {
 8     private static class Person {
 9         private String name;
10         private Integer age;
11 
12         public Person(String name, Integer age) {
13             this.name = name;
14             this.age = age;
15         }
16 
17         public String getName() {
18             return name;
19         }
20 
21         public void setName(String name) {
22             this.name = name;
23         }
24 
25         public Integer getAge() {
26             return age;
27         }
28 
29         public void setAge(Integer age) {
30             this.age = age;
31         }
32 
33         @Override
34         public String toString() {
35             return "Person{" +
36                     "name='" + name + '\'' +
37                     ", age=" + age +
38                     '}';
39         }
40     }
41 
42     private static String function(Person person, Function<Person, String> function) {
43         return function.apply(person);
44     }
45 
46     private static double intFunction(int i, IntFunction<Double> function) {
47         return function.apply(i);
48     }
49 
50     private static Person biFunction(String name, Integer age, BiFunction<String, Integer, Person> function) {
51         return function.apply(name, age);
52     }
53 
54     public static void main(String[] args) {
55         String result1 = function(new Person("zhangsan", 18), Person::getName);
56         System.out.println(result1);
57 
58         double result2 = intFunction(10, i -> i * 100.0d);
59         System.out.println(result2);
60 
61         Person result3 = biFunction("wangwu", 38, Person::new);
62         System.out.println(result3);
63     }
64 }

Console Output

zhangsan
1000.0
Person{name='wangwu', age=38}