最新java8更新的版本的新特征我们一起来看下
package com.sykean.smartsite.pay.MyTest;
import com.sykean.smartsite.pay.contrant.PayRollCode;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.apache.commons.lang3.RandomStringUtils;
import org.apache.commons.lang3.StringUtils;
import org.aspectj.lang.annotation.Before;
import java.text.ParseException;
import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.format.FormatStyle;
import java.time.temporal.ChronoUnit;
import java.time.temporal.TemporalUnit;
import java.util.*;
import java.util.function.*;
import java.util.stream.Collectors;
/**
* 学习java8 的新特性
*
* @AuThor Administrator
* @ClassName TestJAVA8
* @description java 8
* @date 2020/7/11 0011 15:34
* @modifier Administrator
* @date 2020-07-11 15:34
* @version V1.0
*/
public class TestJAVA8 {
static List<Vehicle> vehicles = new ArrayList<>();
public TestJAVA8() {
}
public static void main(String[] args) {
// test1();
// test2();
// test3();
// test4();
// test5();
// test6();
// testNewDate();
// timeMath();
// OneHundrudDay();
dateTest();
}
private static void dateTest() {
String[] lineArr = {"1","2","20200720","133722123"};
Date tradeTime = new Date();
try {
tradeTime = PayRollCode.PAYCODE_YYMMDDHHMMSS_FORMAT.parse(lineArr[2].trim() + lineArr[3].trim());
} catch (ParseException e) {
e.printStackTrace();
}
System.out.println(tradeTime);
}
private static void OneHundrudDay() {
LocalDate birthday = LocalDate.of(2020,4,20);
System.out.println(birthday);
LocalDate now = LocalDate.now();
System.out.println(now);
Period period = Period.between(birthday,now);
// 计算2个日期之间相差的 年月日
System.out.println(period.getYears() + "-" + period.getMonths() + "-" + period.getDays());
// 计算2个日期相隔日期，不包含首位
long between1 = ChronoUnit.DAYS.between(birthday, now);
long oneHundre = 100L;
long diffDay = oneHundre - between1 - 1;
System.out.println("再过" + diffDay + "天过百天");
System.out.println("咱娃出生天数：" + (between1 + 1L));
// 计算相隔月份
long between2 = ChronoUnit.MONTHS.between(birthday, now);
System.out.println("咱娃出生月数：" + between2);
// 几月几日刚好百天？
LocalDate thatDay = now.plusDays(diffDay);
System.out.println("过百天的日期：" + thatDay);
}
private static void timeMath() {
// 创建一个两周的间隔
Period periodWeeks = Period.ofWeeks(2);
System.out.println(periodWeeks.getDays());
// 一年三个月零二天的间隔
Period custom = Period.of(1, 3, 2);
List<TemporalUnit> t = custom.getUnits();
// 一天的时长
Duration duration = Duration.ofDays(1);
System.out.println(duration.getSeconds());
// 计算2015/6/16 号到现在 2019/09/22 过了多久，它这个把间隔分到每个 part 了
LocalDate now = LocalDate.now();
LocalDate customDate = LocalDate.of(2015, 6, 16);
Period between = Period.between(customDate, now);
// 结果为 4:3:6 即过去了 4年3个月6天了
System.out.println(between.getYears() + ":" + between.getMonths() + ":" + between.getDays());
// 比较两个瞬时的时间间隔
Instant begin = Instant.now();
Instant end = Instant.now();
Duration d = Duration.between(begin, end);
System.out.println(d.getNano());
// 同样可以修改 part 信息和设置 part 信息，都是返回新的对象来表示设置过的值，原来的对象不变
Period plusDays = between.plusDays(1);
System.out.println(plusDays);
Period withDays = between.withDays(4);
System.out.println(withDays);
}
private static void testNewDate() {
// 测试执行一个 new 操作使用的时间(纳秒值)
Instant begin = Instant.now();
Instant end = Instant.now();
System.out.println(Duration.between(begin, end).toNanos());
// 可以使用 of 方法构建它们的实例,如下面创建了一个 2019-9-22 21:42:59 东八区 的时间对象
LocalDate localDate = LocalDate.of(2019, Month.SEPTEMBER, 22);
System.out.println(localDate);
LocalTime localTime = LocalTime.of(21, 42, 59);
System.out.println(localTime);
LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime);
System.out.println(localDateTime);
ZonedDateTime zonedDateTime = ZonedDateTime.of(localDateTime, ZoneId.systemDefault());
System.out.println(zonedDateTime);
// 获取现在的时间，这是一个静态方法
LocalDate now = LocalDate.now();
System.out.println(now);
// 每个实例可以获取它们的 part 信息,如获取年
int year = localDate.getYear();
System.out.println(year);
// 可以修改 part 信息，这将返回一个新对象，如增加一年
LocalDate localDatePlus = localDate.plusYears(1);
System.out.println(localDatePlus);
// 设置 part 信息，也会返回新的对象，如设置为 2017 年
LocalDate localDateWithYear = localDate.withYear(2017);
System.out.println(localDateWithYear);
// 比较两个日期 isAfter,isBefore
boolean after = localDate.isAfter(LocalDate.now());
System.out.println(after);
System.out.println("现在时间：" + now);
// 格式化日期时间
// yyyy-MM-dd
System.out.println(now.format(DateTimeFormatter.ISO_DATE));
// yyyy-MM-ddTHH:mm:ss
ZoneId zoneId = ZoneId.systemDefault();
System.out.println(zoneId);
Set<String> availableZoneIds = ZoneId.getAvailableZoneIds();
System.out.println(availableZoneIds);
LocalDateTime now2 = LocalDateTime.now(zoneId);
System.out.println(now2.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME));
// yyyy-MM-dd HH:mm:ss
System.out.println(now2.format(DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM)));
// 日期解析
System.out.println(LocalDate.parse("2019-09-22"));
System.out.println(LocalDateTime.parse("2019-09-22T21:05:22"));
System.out.println(LocalDateTime.parse("2019-09-22 21:05:22" , DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM)));
}
private static void test6() {
Map<String, Integer> map = new HashMap<>();
map.put("a" , 1);
map.put("b" , 2);
map.put("c" , 3);
map.forEach((k, v) -> System.out.println(k + "：这么着就能遍历了" + v));
// 假设有一个对象 obj ,你不知道它是不是为空的，但是你想用它的方法，可以这么玩
Object obj = 1;
Optional<Object> canUseObj = Optional.ofNullable(obj);
System.out.println(canUseObj.isPresent());
canUseObj.ifPresent(System.out::println); //如果 obj 不为空，则可以使用 obj 的方法，这里做个简单输出
}
private static void test5() {
TestJAVA8 t = new TestJAVA8();
t.initVehicles();
vehicles.forEach(System.out::println);
// 去掉评分为 3 分以下的车
List<Vehicle> collect1 =
vehicles.stream().filter(vehicle -> vehicle.getScore() >= 3).collect(Collectors.toList());
System.out.println("去掉评分为 3 分以下的车" + collect1);
// 取出所有的车架号列表
List<String> vins = vehicles.stream().map(Vehicle::getVin).collect(Collectors.toList());
System.out.println(" 取出所有的车架号列表" + vins);
// 按照公司 Id 进行分组
Map<Integer, List<Vehicle>> companyVehicles = vehicles.stream().collect(Collectors.groupingBy(Vehicle::getCompanyId));
System.out.println("按照公司 Id 进行分组" + companyVehicles);
// 按照公司分组求司机打分和
Map<Integer, Double> collect2 = vehicles.stream().collect(Collectors.groupingBy(Vehicle::getCompanyId,
Collectors.summingDouble(Vehicle::getScore)));
System.out.println("按照公司分组求司机打分和" + collect2);
// 查出所有车绑定的所有设备
List<String> collect3 = vehicles.stream().map(vehicle -> {
String deviceNos = vehicle.getDeviceNos();
return StringUtils.split(deviceNos, ',');
}).flatMap(Arrays::stream).collect(Collectors.toList());
System.out.println(" 查出所有车绑定的所有设备" + collect3);
// 对所有司机的总分求和
Double reduce = vehicles.stream().parallel().map(Vehicle::getScore).reduce(0d, Double::sum);
System.out.println("对所有司机的总分求和" + reduce);
// 总的分值
Double totalScore = vehicles.stream().parallel().map(Vehicle::getScore).reduce(0d, Double::sum);
// 查看每一个司机占的分值比重
List<String> collect4 = vehicles.stream()
.mapToDouble(vehicle -> vehicle.getScore() / totalScore)
.mapToLong(weight -> (long) (weight * 100))
.mapToObj(percentage -> percentage + "%")
.collect(Collectors.toList());
System.out.println("查看每一个司机占的分值比重" + collect4);
}
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Vehicle {
//车架号
private String vin;
// 车主手机号
private String phone;
// 车主姓名
private String name;
// 所属车租车公司
private Integer companyId;
// 个人评分
private Double score;
//安装的设备列表imei,使用逗号分隔
private String deviceNos;
}
@Before("")
public void initVehicles() {
List<String> imeis = new ArrayList<>();
for (int i = 0; i < 5; i++) {
List<String> singleVehicleDevices = new ArrayList<>();
for (int j = 0; j < 3; j++) {
String imei = RandomStringUtils.randomAlphanumeric(15);
singleVehicleDevices.add(imei);
}
imeis.add(StringUtils.join(singleVehicleDevices, ','));
}
vehicles.add(new Vehicle("KPTSOA1K67P081452" , "17620411498" , "9420" , 1, 4.5, imeis.get(0)));
vehicles.add(new Vehicle("KPTCOB1K18P057071" , "15073030945" , "张玲" , 2, 1.4, imeis.get(1)));
vehicles.add(new Vehicle("KPTS0A1K87P080237" , "19645871598" , "sanri1993" , 1, 3.0, imeis.get(2)));
vehicles.add(new Vehicle("KNAJC526975740490" , "15879146974" , "李种" , 1, 3.9, imeis.get(3)));
vehicles.add(new Vehicle("KNAJC521395884849" , "13520184976" , "袁绍" , 2, 4.9, imeis.get(4)));
}
private static void test4() {
// hello world 示例
Function<String, String> function = (x) -> {
return x;
};
System.out.println(function.apply("hello world")); // hello world Function
UnaryOperator<String> unaryOperator = x -> x + 2;
System.out.println(unaryOperator.apply("9420-")); // 9420-2
// 判断输入值是否为偶数示例
Predicate<Integer> predicate = (x) -> {
return x % 2 == 0;
};
System.out.println(predicate.test(1)); // false
// 这个没有返回值
Consumer<String> consumer = (x) -> {
System.out.println(x);
};
consumer.accept("hello world "); // hello world
// 这个没有输入
Supplier<String> supplier = () -> {
return "Supplier";
};
System.out.println(supplier.get()); // Supplier
// 找出大数
BinaryOperator<Integer> bina = (x, y) -> {
return x > y ? x : y;
};
bina.apply(1, 2);
}
private static void test3() {
final String se = ",";
Arrays.asList("a" , "b" , "c").forEach(e -> System.out.println(e));
}
private static void test2() {
int[] a = {1, 3456, 67, 8, 6, 345, 3, 453, 45};
List aa = Arrays.asList(a);
aa.forEach(System.out::println);
aa.add(456);
}
private static void test1() {
Runnable r = () -> System.out.println("Fuck U!");
r.run();
Arrays.asList("a" , "b" , "d").forEach(System.out::println);
}
} |
整体变化不是很大，细节方面做了优化。 |
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