package com.expgiga.Java8;
/**
*
*/
public class Employee {
private String
name;
private int age;
private double salary;
private int id;
private Status
status;
public Employee() {
}
public Employee(String name,
int age,
double salary) {
this.
name = name;
this.
age = age;
this.
salary = salary;
}
public Employee(String name,
int age,
double salary, Status status) {
this.
name = name;
this.
age = age;
this.
salary = salary;
this.
status = status;
}
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 +
", id=" +
id +
", status=" +
status +
'}';
}
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;
}
public Status getStatus() {
return status;
}
public void setStatus(Status status) {
this.
status = status;
}
public enum Status {
FREE,
BUSY,
VOCATION;
}
}
package com.expgiga.Java8;
import java.util.*;
import java.util.stream.Collector;
import java.util.stream.Collectors;
/**
* Java8 Stream的终止操作:
*/
public class TestStreamAPI {
public static void main(String[] args) {
/*
* 查找与匹配
* allMatch
* anyMatch
* noneMatch
* findFirst
* findAny
* count
* max
* min
*
*/
List<Employee> employeeList = Arrays.
asList(
new Employee(
"zhangsan",
18,
19999, Employee.Status.
FREE),
new Employee(
"lisi",
28,
29999, Employee.Status.
BUSY),
new Employee(
"wangwu",
38,
39999, Employee.Status.
VOCATION),
new Employee(
"zhaoliu",
16,
17999, Employee.Status.
BUSY),
new Employee(
"tianqi",
6,
12999, Employee.Status.
FREE),
new Employee(
"tianqi",
6,
12999, Employee.Status.
FREE)
);
/*
* 归约
* reduce
*/
List<Integer> list = Arrays.
asList(
1,
2,
3,
4,
5,
6,
7,
8,
9,
10);
Integer sum = list.stream()
.reduce(
0, (x, y) -> x + y);
System.
out.println(sum);
System.
out.println(
"-----------------------------------------------");
Optional<Double> op = employeeList.stream()
//可能为空 所有返回的是Optional
.map(Employee::getSalary)
.reduce(Double::
sum);
System.
out.println(op.get());
/*
* 收集
* collect
*/
List<String> list2 = employeeList.stream()
.map(Employee::getName)
.collect(Collectors.
toList());
list2.forEach(System.
out::println);
Set<String> set = employeeList.stream()
.map(Employee::getName)
.collect(Collectors.
toSet());
set.forEach(System.
out::println);
System.
out.println(
"-----------------------------------------------");
HashSet<String> hs = employeeList.stream()
.map(Employee::getName)
.collect(Collectors.
toCollection(HashSet::
new));
hs.forEach(System.
out::println);
//总数
Long count = employeeList.stream()
.collect(Collectors.
counting());
System.
out.println(count);
//平均值
Double avg = employeeList.stream()
.collect(Collectors.
averagingDouble(Employee::getSalary));
System.
out.println(avg);
//总和
Double sumSalary = employeeList.stream()
.collect(Collectors.
summingDouble(Employee::getSalary));
System.
out.println(sumSalary);
//最大值
Optional<Employee> max = employeeList.stream()
.collect(Collectors.
maxBy((e1, e2) -> Double.
compare(e1.getSalary(), e2.getSalary())));
System.
out.println(max.get());
//最小值
Optional<Double> min = employeeList.stream()
.map(Employee::getSalary)
.collect(Collectors.
minBy(Double::
compare));
System.
out.println(min.get());
//分组
Map<Employee.Status, List<Employee>> map = employeeList.stream()
.collect(Collectors.
groupingBy(Employee::getStatus));
System.
out.println(map);
//多级分组
Map<Employee.Status, Map<String, List<Employee>>> mapMap = employeeList.stream()
.collect(Collectors.
groupingBy(Employee::getStatus, Collectors.
groupingBy((e) -> {
if (((Employee)e).getAge() <=
18) {
return "dud";
}
else if(((Employee)e).getAge() <=
30) {
return "heh";
}
else {
return "hah";
}
})));
System.
out.println(mapMap);
//分片(分区)
Map<Boolean, List<Employee>> booleanListMap = employeeList.stream()
.collect(Collectors.
partitioningBy((e) -> e.getSalary() >
13000));
System.
out.println(booleanListMap);
//其他
DoubleSummaryStatistics dss = employeeList.stream()
.collect(Collectors.
summarizingDouble(Employee::getSalary));
System.
out.println(dss.getSum());
String str = employeeList.stream()
.map(Employee::getName)
.collect(Collectors.
joining());
System.
out.println(str);
}
}
