Java8 Stream映射

package com.expgiga.Java8;/** * */public class Employee {    private String name;    private int age;    private double salary;    private int id;    public Employee() {    }    public Employee(String name, int age, double salary) {        this.name = name;        this.age = age;        this.salary = salary;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public double getSalary() {        return salary;    }    public void setSalary(double salary) {        this.salary = salary;    }    @Override    public String toString() {        return "Employee{" +                "name='" + name + '\'' +                ", age=" + age +                ", salary=" + salary +                '}';    }    public Employee(int id) {        this.id = id;    }    public Employee(int id, int age) {        this.id = id;        this.age = age;    }    @Override    public boolean equals(Object o) {        if (this == o) return true;        if (o == null || getClass() != o.getClass()) return false;        Employee employee = (Employee) o;        if (age != employee.age) return false;        if (Double.compare(employee.salary, salary) != 0) return false;        if (id != employee.id) return false;        return name != null ? name.equals(employee.name) : employee.name == null;    }    @Override    public int hashCode() {        int result;        long temp;        result = name != null ? name.hashCode() : 0;        result = 31 * result + age;        temp = Double.doubleToLongBits(salary);        result = 31 * result + (int) (temp ^ (temp >>> 32));        result = 31 * result + id;        return result;    }}

package com.expgiga.Java8;import java.util.ArrayList;import java.util.Arrays;import java.util.Iterator;import java.util.List;import java.util.stream.Stream;/** * Java8 Stream * * 一、Stream的三个操作步骤： * 1. 创建Stream * 2. 中间操作 * 3. 终止操作(终端操作) */public class TestStream2 {    public static void main(String[] args) {        /*         * 中间操作：         * filter:接受Lambda，从流中排出某些元素。         * limit:截断流，使其元素不超过给定数量         * skip:跳过元素，返回一个扔掉了前n个元素的流。若流中元素不足n个，则返回一个空流。与Limit(n)互补         * distinct:筛选，通过流所生成元素的hashCode()和equals()去除重复元素         *         */        //内部迭代：迭代操作由Stream API完成        List<Employee> employeeList = Arrays.asList(                new Employee("zhangsan", 18, 19999),                new Employee("lisi", 28, 29999),                new Employee("wangwu", 38, 39999),                new Employee("zhaoliu", 16, 17999),                new Employee("tianqi", 6, 12999),                new Employee("tianqi", 6, 12999),                new Employee("tianqi", 6, 12999)        );        /*         * 映射         * map         * flatMap         */        //map        List<String> list = Arrays.asList("aa", "bb", "cc", "dd", "ee");        list.stream()                .map((str) -> str.toUpperCase())                .forEach(System.out::println);        employeeList.stream()                .map(Employee::getName)                .forEach(System.out::println);        //        Stream<Stream<Character>> streamStream =  list.stream()                .map(TestStream2::filterCharacter);        streamStream.forEach((sm) -> {            sm.forEach(System.out::println); //{{a,a},{b,b},{c,c},{d,d},{e,e}}        });        //flatMap        list.stream()                .flatMap(TestStream2::filterCharacter)                .forEach(System.out::println);//{a,a,b,b,c,c,d,d,e,e}        //对比add(Object obj) addAll(Collection coll)        List list2 = new ArrayList<>();        list2.add(11);        list2.add(22);        list2.add(33);        list2.add(list);        System.out.println(list2);        list2.addAll(list);        System.out.println(list2);    }    private static Stream<Character> filterCharacter(String str) {        List<Character> list = new ArrayList<>();        for (Character ch : str.toCharArray()) {            list.add(ch);        }        return list.stream();    }}