Lambda Expression -Function

原创转载请注明出处：http://agilestyle.iteye.com/blog/2424769

 

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)

 

e.g.

package org.fool.java8;

import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.IntFunction;

public class FunctionTest {
    private static class Person {
        private String name;
        private Integer age;

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

        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;
        }

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

    private static String function(Person person, Function<Person, String> function) {
        return function.apply(person);
    }

    private static double intFunction(int i, IntFunction<Double> function) {
        return function.apply(i);
    }

    private static Person biFunction(String name, Integer age, BiFunction<String, Integer, Person> function) {
        return function.apply(name, age);
    }

    public static void main(String[] args) {
        String result1 = function(new Person("zhangsan", 18), Person::getName);
        System.out.println(result1);

        double result2 = intFunction(10, i -> i * 100.0d);
        System.out.println(result2);

        Person result3 = biFunction("wangwu", 38, Person::new);
        System.out.println(result3);
    }
}

 Console Output

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