├── Java 8函数式编程.pdf ├── Java 8实战.pdf ├── README.md ├── pom.xml └── src └── main └── java ├── Optional └── OptionalTest.java ├── date ├── DataExcample2.java └── DateExample.java ├── javaScript └── JavaScriptDemo.java ├── lambda ├── InterfaceInner.java ├── LambdaExample.java ├── LamdbaTest.java ├── User.java ├── UserArgsInterface.java └── UserInterface.java ├── methodReference ├── MethodReference.java └── Student.java └── stream └── SteamMethod.java /Java 8函数式编程.pdf: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/eratel/JDK8/c8b147f0067c200f3f2521f652854cb0b24d412e/Java 8函数式编程.pdf -------------------------------------------------------------------------------- /Java 8实战.pdf: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/eratel/JDK8/c8b147f0067c200f3f2521f652854cb0b24d412e/Java 8实战.pdf -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | * GitHub: https://github.com/ABHSY 2 | * author: ABHSY.Klein 3 | 4 | 5 | **有相对jvm 多线程并发 以及 lamdba 函数式编程的小伙伴。** 6 | * 感兴趣的添加我的**Q425359983** 7 | * 或有问题咨询也加**Q425359983** 8 | 9 | 10 | **对微服务有兴趣的可以看我的springclound的Repositiories** 11 | * 技术范围:包含EUREKA FEIGN ZULL HYSTRIX ZULL SPRINGCONFIG TUBINE HYSTRIXDASHBORD 以及通过sidecar 异构非java语言的微服务 12 | * GitHub:https://github.com/ABHSY/springCloud.git 13 | 14 | **对前端有兴趣的小伙伴可以看我的前端博客**
15 | * 技术范围:vue + vue-cli + element + vue-rouse + vue-router + es6 + webpack 16 | * GitHub:https://github.com/ABHSY/VUE-CLI-ELEMENTUI.git 17 | 18 | 19 | * 刚入门的小伙伴可以看我的springBoot 集成 20 | * mybatis quartz servert sole task springData 21 | -------------------------------------------------------------------------------- /pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 5 | 4.0.0 6 | 7 | groupId 8 | jdk8 9 | 1.0-SNAPSHOT 10 | 11 | 12 | 13 | org.apache.maven.plugins 14 | maven-compiler-plugin 15 | 16 | 1.8 17 | 1.8 18 | 19 | 20 | 21 | 22 | 23 | 24 | org.projectlombok 25 | lombok 26 | 1.16.16 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | junit 35 | junit 36 | 4.12 37 | 38 | 39 | org.apache.commons 40 | commons-lang3 41 | 3.4 42 | 43 | 44 | 45 | 46 | -------------------------------------------------------------------------------- /src/main/java/Optional/OptionalTest.java: -------------------------------------------------------------------------------- 1 | package Optional; 2 | 3 | import lambda.User; 4 | import org.junit.Test; 5 | 6 | import java.util.Optional; 7 | 8 | /** 9 | * @program: jdk8 10 | * @GitHub: https://github.com/ABHSY 11 | * @author: ABHSY.Jason 12 | * @create: 2018-03-31 16:16 13 | * 接口调用 14 | **/ 15 | public class OptionalTest { 16 | 17 | public void test(User u){ 18 | Optional optional = Optional.ofNullable(u); 19 | System.out.println(optional.orElse("nullPoint")); 20 | } 21 | @Test 22 | public void test2(){ 23 | test(new User()); 24 | test(null); 25 | } 26 | } 27 | -------------------------------------------------------------------------------- /src/main/java/date/DataExcample2.java: -------------------------------------------------------------------------------- 1 | package date; 2 | 3 | import org.junit.Test; 4 | 5 | import java.time.LocalDate; 6 | import java.time.LocalTime; 7 | import java.time.MonthDay; 8 | 9 | 10 | public class DataExcample2 { 11 | private LocalDate today = LocalDate.now(); 12 | 13 | @Test 14 | public void testData(){ 15 | LocalDate of = LocalDate.of(2014,4,1); 16 | // System.out.print(of.equals(today)); 17 | 18 | LocalDate localDate = today.plusDays(1); 19 | // boolean after = localDate.isAfter(of); 20 | System.out.print(localDate.isBefore(of)); 21 | 22 | 23 | LocalDate datebirth = LocalDate.of(1994, 4, 1); 24 | MonthDay of1 = MonthDay.of(datebirth.getMonth(), datebirth.getDayOfMonth()); 25 | MonthDay currentMonthDay = MonthDay.from(today); 26 | 27 | 28 | } 29 | 30 | @Test 31 | public void equalsData(){ 32 | LocalDate of = LocalDate.of(2014, 4, 1); 33 | 34 | LocalDate localDate = today.plusDays(1); 35 | System.out.print(today.isAfter(of)); 36 | 37 | } 38 | 39 | 40 | } 41 | -------------------------------------------------------------------------------- /src/main/java/date/DateExample.java: -------------------------------------------------------------------------------- 1 | package date; 2 | 3 | import org.junit.Test; 4 | 5 | import java.time.*; 6 | import java.time.format.DateTimeFormatter; 7 | import java.time.temporal.ChronoUnit; 8 | import java.time.temporal.TemporalAdjusters; 9 | 10 | import static java.time.temporal.ChronoUnit.DAYS; 11 | 12 | /** 13 | * jdk8 时间处理 14 | * 用到的方法都是线程安全的 15 | */ 16 | public class DateExample { 17 | private LocalDate today = LocalDate.now(); 18 | 19 | /** 20 | * 时间相关的获取 21 | */ 22 | @Test 23 | public void test() { 24 | //获取当前日期 25 | System.out.println("今天的日期 : " + today); 26 | 27 | 28 | //获取单独的年月日 29 | int year = today.getYear(); 30 | int month = today.getMonthValue(); 31 | int day = today.getDayOfMonth(); 32 | System.out.printf("Year : %d Month : %d day : %d \t %n", year, month, day); 33 | 34 | 35 | //输出当前时间 不包含日期 36 | LocalDateTime now = LocalDateTime.now(); 37 | LocalTime time = LocalTime.now(); 38 | System.out.println("LocalDateTime : " + now.format(DateTimeFormatter.ofPattern("yyyy/MM/dd/hh/ss"))); 39 | 40 | //输出当前的日期和时间 41 | LocalDateTime localDateTime = LocalDateTime.now(); 42 | System.out.println("今天的时间和日期：" + localDateTime); 43 | } 44 | 45 | /** 46 | * 时间相关的比较、检查和验证 47 | */ 48 | @Test 49 | public void test2() { 50 | 51 | 52 | //LocalDate重写了equals方法，可以直接比较两个LocalDate 53 | LocalDate date1 = LocalDate.of(2014, 1, 14); 54 | if (!date1.equals(today)) { 55 | System.out.printf("Today %s and date1 %s are same date %n", today, date1); 56 | } 57 | 58 | 59 | //日期大小比较 60 | LocalDate tomorrow = today.plusDays(1); 61 | if (tomorrow.isAfter(today)) { 62 | System.out.println("Tomorrow comes after today"); 63 | } 64 | LocalDate yesterday = today.minus(1, ChronoUnit.DAYS); 65 | if (yesterday.isBefore(today)) { 66 | System.out.println("Yesterday is day before today"); 67 | } 68 | 69 | 70 | //日期检查 71 | LocalDate dateOfBirth = LocalDate.of(2017, 5, 16); 72 | MonthDay birthday = MonthDay.of(dateOfBirth.getMonth(), dateOfBirth.getDayOfMonth()); 73 | MonthDay currentMonthDay = MonthDay.from(today); 74 | if (currentMonthDay.equals(birthday)) { 75 | System.out.println("Many Many happy returns of the day !!"); 76 | } else { 77 | System.out.println("Sorry, today is not your birthday"); 78 | } 79 | 80 | 81 | YearMonth yearMonth = YearMonth.now(); 82 | DayOfWeek dayOfWeek = DayOfWeek.of(2); 83 | System.out.println("年月：" + yearMonth); 84 | System.out.println("几号：" + MonthDay.now()); 85 | System.out.println("星期几：" + dayOfWeek); 86 | 87 | //检查是否是闰年 88 | System.out.println(today.isLeapYear()); 89 | System.out.println(today.minus(1, ChronoUnit.YEARS).isLeapYear()); 90 | 91 | 92 | LocalDate addMonth = today.plusMonths(-2).plusWeeks(2).plusDays(2); 93 | 94 | 95 | //Period是一个时间容器,做比较比较好用 96 | Period period = Period.between(addMonth, today); 97 | //两个日期相差的天数 月份并不会转换成天数。相应的也有getMonths() getYear()方法 98 | System.out.println(period.getDays()); 99 | //这个方法为判断传入的年月日是否是负数，不知道是啥用 100 | period.isNegative(); 101 | //在当前年月日的基础之上加上指定的天数，月份或者年份 102 | System.out.println(period.withDays(2).getDays()); 103 | //该方法判断Period容器中的年月日是否都是0 104 | period.isZero(); 105 | //将Period中的年月日进行翻倍 106 | period = period.multipliedBy(3); 107 | System.out.println(period.getDays()); 108 | //将时间差进行反转，比如year:2 month:-1 day:15 转换成 year:-2 month: 1 day: -15 109 | period.negated(); 110 | //将年转换成月之后，统计总月数 111 | period.toTotalMonths(); 112 | //将总月份或者年加上超过12个月的月份，根据一年12个月进行格式化。 113 | period.normalized(); 114 | 115 | } 116 | 117 | /** 118 | * 时间格式转换 119 | */ 120 | @Test 121 | public void test3() { 122 | 123 | 124 | //时间转换 125 | String dayAfterTommorrow = "20170516"; 126 | //2014-01-16 127 | LocalDate formatted = LocalDate.parse(dayAfterTommorrow, 128 | DateTimeFormatter.BASIC_ISO_DATE); 129 | //DateTimeFormatter 内置了很多时间格式化器 同上 130 | System.out.printf("Date generated from String %s is %s %n", dayAfterTommorrow, formatted); 131 | 132 | //这种格式的可以直接parse 133 | LocalDate endOfFeb = LocalDate.parse("2017-05-16"); 134 | System.out.println(endOfFeb); 135 | 136 | //自定义格式 137 | String goodFriday = "05 18 2017"; 138 | DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM dd yyyy"); 139 | LocalDate holiday = LocalDate.parse(goodFriday, formatter); 140 | System.out.printf("Successfully parsed String %s, date is %s%n", goodFriday, holiday); 141 | } 142 | 143 | /** 144 | * 时间相关的操作 和一些常用的时间提取 145 | */ 146 | @Test 147 | public void test1() { 148 | 149 | 150 | //自定义日期 151 | LocalDate dateOfBirths = LocalDate.of(2010, 1, 14); 152 | System.out.println("Your Date of birth is : " + dateOfBirths); 153 | 154 | 155 | //时间变化 156 | LocalDate addToday = today.plusDays(2); 157 | LocalDate addMonth = today.minusDays(1); 158 | //Duration这个类没用懂 类似的方法在165行 159 | // System.out.println("测试minus ：" + today.minus(Duration.ofDays(1589713165))); 160 | 161 | 162 | //增加两个世纪 163 | LocalDate newEras = today.plus(2, ChronoUnit.CENTURIES); 164 | System.out.println(addToday); 165 | System.out.println(newEras); 166 | 167 | 168 | //minus和plus是相反的 也是修改日期相关的 169 | LocalDate previousYear = today.minus(1, ChronoUnit.YEARS); 170 | System.out.println("Date before 1 year : " + previousYear); 171 | LocalDate nextYear = today.plus(1, ChronoUnit.YEARS); 172 | System.out.println("Date after 1 year : " + nextYear); 173 | 174 | 175 | //时间戳 176 | Instant timestamp = Instant.now(); 177 | System.out.println("time:" + timestamp.getEpochSecond()); 178 | 179 | Instant instant = Instant.ofEpochSecond(timestamp.getEpochSecond()); 180 | System.out.println(LocalDateTime.ofInstant(instant, ZoneId.of("Asia/Shanghai"))); 181 | 182 | 183 | //TemporalAdjusters封装很多提取时间的方法 184 | // 取本月第1天： 185 | LocalDate firstDayOfThisMonth = today.with(TemporalAdjusters.firstDayOfMonth()); // 2014-12-01 186 | // 取本月第2天： 187 | LocalDate secondDayOfThisMonth = today.withDayOfMonth(2); // 2014-12-02 188 | // 取本月最后一天，再也不用计算是28，29，30还是31： 189 | LocalDate lastDayOfThisMonth = today.with(TemporalAdjusters.lastDayOfMonth()); // 2014-12-31 190 | // 取下一天： 191 | LocalDate firstDayOf2015 = lastDayOfThisMonth.plusDays(1); // 变成了2015-01-01 192 | // 取2015年1月第一个周一，这个计算用Calendar要死掉很多脑细胞： 193 | LocalDate firstMondayOf2015 = LocalDate.parse("2015-01-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY)); // 2015-01-05 194 | 195 | //以下方法基本上都是LocalDate LocalDateTime LocalTime三个类通用的，小有区别 196 | //今年的第355天的日期 197 | System.out.println("测试withDayOfYear ：" + today.withDayOfYear(355)); 198 | //当前日期的在一月的日期，如果当前日期的在响应的月份没有则取当月的最后一天。比如取3月31,如果月份换成2月，2月没有31天它会直接判断今年是平年还是闰年然后取最后一天。 199 | System.out.println("测试withDayOfMonth ：" + today.withMonth(1)); 200 | System.out.println("测试：" + LocalDate.now().plusDays(14).withMonth(2)); 201 | //本月第二天的日期 202 | System.out.println("测试withDayOfWeek：" + today.withDayOfMonth(2)); 203 | //显示哪一年的今天的日期 204 | System.out.println("测试withYear" + today.withYear(1995)); 205 | 206 | 207 | //TemporalAdjusters有封装的选取指定日期的方法。如今年的第一天，明年的第一天，下个月的最后一天，本月的最后一天等等方法都有封装 208 | //返回今天零点的LocalDateTime 209 | System.out.println("返回今天零点的LocalDateTime：" + today.atStartOfDay()); 210 | //返回一个今天的指定时区的ZoneDateTime 211 | System.out.println("返回一个今天的达尔文的ZoneDateTime : " + today.atStartOfDay(ZoneId.of("Australia/Darwin"))); 212 | //返回今天两点二十的时间 213 | System.out.println(today.atTime(2, 20)); 214 | System.out.println(today.atTime(LocalTime.of(2, 20, 20, 321))); 215 | } 216 | 217 | @Test 218 | public void test5() { 219 | //时钟 220 | /* 221 | map.put("ACT", "Australia/Darwin"); 222 | map.put("AET", "Australia/Sydney"); 223 | map.put("AGT", "America/Argentina/Buenos_Aires"); 224 | map.put("ART", "Africa/Cairo"); 225 | map.put("AST", "America/Anchorage"); 226 | map.put("BET", "America/Sao_Paulo"); 227 | map.put("BST", "Asia/Dhaka"); 228 | map.put("CAT", "Africa/Harare"); 229 | map.put("CNT", "America/St_Johns"); 230 | map.put("CST", "America/Chicago"); 231 | map.put("CTT", "Asia/Shanghai"); 232 | map.put("EAT", "Africa/Addis_Ababa"); 233 | map.put("ECT", "Europe/Paris"); 234 | map.put("IET", "America/Indiana/Indianapolis"); 235 | map.put("IST", "Asia/Kolkata"); 236 | map.put("JST", "Asia/Tokyo"); 237 | map.put("MIT", "Pacific/Apia"); 238 | map.put("NET", "Asia/Yerevan"); 239 | map.put("NST", "Pacific/Auckland"); 240 | map.put("PLT", "Asia/Karachi"); 241 | map.put("PNT", "America/Phoenix"); 242 | map.put("PRT", "America/Puerto_Rico"); 243 | map.put("PST", "America/Los_Angeles"); 244 | map.put("SST", "Pacific/Guadalcanal"); 245 | map.put("VST", "Asia/Ho_Chi_Minh"); 246 | map.put("EST", "-05:00"); 247 | map.put("MST", "-07:00"); 248 | map.put("HST", "-10:00"); 249 | */ 250 | LocalDateTime datetime = LocalDateTime.of(2017, Month.JANUARY, 14, 19, 30); 251 | ZoneOffset offset = ZoneOffset.of("+05:30"); 252 | OffsetDateTime date = OffsetDateTime.of(datetime, offset); 253 | System.out.println("Date and Time with timezone offset in Java : " + date); 254 | 255 | 256 | //拿取偏移量 257 | ZonedDateTime zonedDateTime = ZonedDateTime.of(LocalDateTime.now(), ZoneId.of("America/New_York")); 258 | ZonedDateTime china = ZonedDateTime.of(LocalDateTime.now(), ZoneId.of("Asia/Shanghai")); 259 | ZonedDateTime Darwin = ZonedDateTime.of(LocalDateTime.now(), ZoneId.of("Australia/Darwin")); 260 | System.out.println("America : " + zonedDateTime.format(DateTimeFormatter.ISO_ZONED_DATE_TIME)); 261 | System.out.println("China : " + china); 262 | 263 | 264 | //拿取具体时区的时间 265 | System.out.println("偏移时间" + LocalDateTime.now(Clock.fixed(Instant.now(), ZoneId.of("Australia/Darwin")))); 266 | System.out.println("Darwin : " + Darwin.getOffset()); 267 | System.out.println("Now : " + LocalDateTime.now()); 268 | } 269 | /* 270 | 总结： 271 | LocalDate、LocalDate、LocalDateTime、YearMonth、MonthDay、DayOfWeek都支持 ： 272 | plus加时间， 273 | minus减时间， 274 | */ 275 | } 276 | -------------------------------------------------------------------------------- /src/main/java/javaScript/JavaScriptDemo.java: -------------------------------------------------------------------------------- 1 | package javaScript; 2 | import org.junit.Test; 3 | 4 | import javax.script.ScriptEngine; 5 | import javax.script.ScriptEngineManager; 6 | import javax.script.ScriptException; 7 | 8 | public class JavaScriptDemo { 9 | @Test 10 | public void test() throws ScriptException { 11 | ScriptEngineManager manager = new ScriptEngineManager(); 12 | ScriptEngine engine = manager.getEngineByName( "JavaScript" ); 13 | System.out.println(engine.getClass().getName()); 14 | String s = "function f() { return 1; }; f() + 1;"; 15 | System.out.println(engine.eval(s)); 16 | } 17 | } 18 | -------------------------------------------------------------------------------- /src/main/java/lambda/InterfaceInner.java: -------------------------------------------------------------------------------- 1 | package lambda; 2 | 3 | import org.junit.Test; 4 | 5 | import java.util.ArrayList; 6 | import java.util.List; 7 | 8 | /** 9 | * @program: jdk8 10 | * @GitHub: https://github.com/ABHSY 11 | * @author: ABHSY.Jason 12 | * @create: 2018-03-31 16:16 13 | * 接口调用 14 | **/ 15 | public class InterfaceInner { 16 | //////////////////////////////////////////////////////////////// 17 | // 接口调用 18 | /** lambda第一种格式，无参 */ 19 | /** 20 | * 无非就是将实现 作为参数 使用lamdba表达式的形式实现 21 | * 然后在类中被调用 22 | */ 23 | @Test 24 | public void test(){ 25 | eat(() -> System.out.println("-----------")); 26 | } 27 | 28 | /** 29 | * 当你在实现底层框架 实现lamdba的形式时。 这块写入base 业务逻辑 30 | * 传输 关键业务逻辑 31 | */ 32 | private void eat(UserInterface c){ 33 | c.eat(); 34 | } 35 | 36 | 37 | /** 38 | * lambda第二种格式 ，有参 39 | */ 40 | @Test 41 | public void test1(){ 42 | study( user -> System.out.println(user.getName())); 43 | } 44 | 45 | private void study(UserArgsInterface c){ 46 | c.study(new User("name",10)); //传入直接代码片段 对接口实现可以这么理解 47 | c.welcome(); //直接执行接口中的方法 48 | } 49 | 50 | 51 | 52 | 53 | 54 | //////////////////////////////////////////////////////////////////////////////////////// 55 | 56 | /** 57 | * for 循环 58 | */ 59 | @Test 60 | public void getLoopList() { 61 | List all = new ArrayList<>(); 62 | for (int i = 0; i < 10; i++) { 63 | all.add(new User("111"+i, 11)); 64 | } 65 | all.forEach(user -> System.out.print(user)); 66 | 67 | } 68 | 69 | public void lambdaLoopList(List list) { 70 | //三行循环效果相同 71 | //list.forEach(user -> System.out.println(user.toString())); 72 | //list.forEach(user -> System.out.println(user));//下面一行代码就是简写形式 73 | list.forEach(System.out::println); 74 | } 75 | } 76 | -------------------------------------------------------------------------------- /src/main/java/lambda/LambdaExample.java: -------------------------------------------------------------------------------- 1 | package lambda; 2 | 3 | import org.junit.Test; 4 | 5 | import java.util.*; 6 | 7 | /** 8 | * @program: jdk8 9 | * @GitHub: https://github.com/ABHSY 10 | * @author: ABHSY.Jason 11 | * @create: 2018-03-31 16:16 12 | * 匿名内部类 比较 等 13 | **/ 14 | public class LambdaExample { 15 | @Test 16 | public void test() { 17 | List wordList = Arrays.asList("123456", "1234", "123", "12", "11111"); 18 | 19 | 20 | System.out.println(compare(wordList)); 21 | System.out.println(compareLambda(wordList)); 22 | System.out.println(compareLambdaFunction(wordList)); 23 | 24 | 25 | } 26 | 27 | //匿名内部类 28 | public List compare(List wordList) { 29 | 30 | wordList.sort(new Comparator() { 31 | @Override 32 | public int compare(String s1, String s2) { 33 | return Integer.compare(s1.length(), s2.length()); 34 | } 35 | }); 36 | return wordList; 37 | } 38 | 39 | //lambda 40 | //Integer.compare 输出结果 大于=1；等于=0；小于=-1 41 | public List compareLambda(List wordList) { 42 | wordList.sort((s1, s2) -> Integer.compare(s1.length(), s2.length())); 43 | return wordList; 44 | } 45 | 46 | //函数(非空验证) 47 | public List compareLambdaFunction(List wordList) { 48 | wordList.sort(Comparator.comparingLong(String::length)); 49 | // wordList.sort(Comparator.comparingLong((a) -> a.length())); 50 | return wordList; 51 | } 52 | 53 | 54 | public void treeSetCompare() { 55 | 56 | Set set = new TreeSet<>(Comparator.comparing(User::getAge)); 57 | //原来的写法 58 | Set oldSet = new TreeSet<>(new Comparator() { 59 | @Override 60 | public int compare(User o1, User o2) { 61 | return o1.getAge() - o2.getAge(); 62 | } 63 | }); 64 | } 65 | 66 | 67 | } 68 | 69 | -------------------------------------------------------------------------------- /src/main/java/lambda/LamdbaTest.java: -------------------------------------------------------------------------------- 1 | package lambda; 2 | 3 | import org.junit.Test; 4 | 5 | import java.text.SimpleDateFormat; 6 | import java.util.*; 7 | import java.util.concurrent.atomic.AtomicInteger; 8 | import java.util.function.Function; 9 | import java.util.stream.Collectors; 10 | import java.util.stream.Stream; 11 | 12 | import static java.util.Arrays.asList; 13 | import static java.util.stream.Collectors.*; 14 | import static junit.framework.Assert.assertEquals; 15 | 16 | /** 17 | * @program: jdk8 18 | * @GitHub: https://github.com/ABHSY 19 | * @author: ABHSY.Jason 20 | * @create: 2018-03-31 16:16 21 | **/ 22 | public class LamdbaTest { 23 | 24 | public static void main(String arg[]) { 25 | List strings = Arrays.asList("name", "name1", "name2"); 26 | long l = fromLondonPrinted(strings); 27 | System.out.print(l); 28 | } 29 | 30 | /** 31 | * filter 过滤数据 32 | */ 33 | public static long fromLondonPrinted(List allArtists) { 34 | // BEGIN internal_count_londoners_printed 35 | long count = allArtists.stream() 36 | .filter(artist -> { 37 | System.out.println(artist); 38 | return artist.equals("name"); 39 | }) 40 | .count(); 41 | // END internal_count_londoners_printed 42 | return count; 43 | } 44 | 45 | @Test 46 | /** 47 | * map 操作符 48 | */ 49 | public void allToUpperCase() { 50 | // Stream a = Stream.of("a", "b", "c"); 51 | // List collect = a.map(string -> string.toUpperCase()) 52 | // .collect(Collectors.toList()); 53 | // System.out.print(collect.toString()); 54 | 55 | List strings = Arrays.asList("a", "b", "c"); 56 | List list = strings.stream().map(a -> { 57 | return a.toUpperCase(); 58 | }).collect(toList()); 59 | //将stream转换为List 的对象 60 | // List collect = stringStream.collect(toList()); 61 | 62 | } 63 | 64 | /** 65 | * 获取最小 最大 66 | */ 67 | @Test 68 | public void streamsMaxLength() { 69 | List uu = asList(new User("Bakai", 524), 70 | new User("Violets for Your Furs", 378), 71 | new User("Time Was", 451)); 72 | 73 | User user = uu.stream() 74 | // .min(Comparator.comparing(u -> u.getAge())) 75 | .max(Comparator.comparing(u -> u.getAge())) 76 | .get(); 77 | System.out.print(user); 78 | } 79 | 80 | /** 81 | * reduce 求和 82 | */ 83 | @Test 84 | public void sumUsingReduce() { 85 | Optional reduce = Stream.of(1, 2, 3) 86 | .reduce((acc, element) -> acc + element); 87 | System.out.print(reduce.get()); 88 | } 89 | 90 | ///////////////////////////////////////////////////////////////////////////////////////////// 91 | //以下是练习 92 | 93 | /** 94 | * 找到对象中 name 开头ba 的年龄是多少 95 | */ 96 | @Test 97 | public void originsOfBands() { 98 | List userList = asList(new User("Bakai", 524), 99 | new User("Violets for Your Furs", 378), 100 | new User("Time Was", 451)); 101 | // BEGIN origins_of_bands 102 | List origins = userList.stream() 103 | //先过滤 104 | .filter(artist -> artist.getName().startsWith("Ba")) 105 | //对年龄进行重新赋值 106 | .map(artist -> artist.getAge()) 107 | //将 值装换 108 | .collect(toList()); 109 | // END origins_of_bands 110 | System.out.print(origins.toString()); 111 | } 112 | 113 | @Test 114 | public void findName() { 115 | List users = asList(new User("Bakai", 524), 116 | new User("Violets for Your Furs", 378), 117 | new User("Time Was", 451)); 118 | Set tn = new HashSet<>(); 119 | users.stream() 120 | .filter(user -> user.getName().startsWith("B")) 121 | .map(user -> user.getName()) 122 | .forEachOrdered(name -> tn.add(name)); 123 | // .forEach(name ->tn.add(name)); 124 | System.out.print(tn); 125 | } 126 | 127 | //计算流中所有数之和 128 | @Test 129 | public void addUP() { 130 | List wordList = Arrays.asList(1, 2, 3); 131 | Optional reduce = wordList.stream().reduce((nu1, nu2) -> nu1 + nu2); 132 | System.out.print(reduce.get()); 133 | } 134 | 135 | 136 | /** 137 | * IntSummaryStatistics int 138 | * LongSummaryStatistics long 139 | * 等等 都包含 man min average sum 这些方法 140 | */ 141 | @Test 142 | public void printTrackLengthStatistics() { 143 | List users = asList(new User("Bakai", 524), 144 | new User("Violets for Your Furs", 378), 145 | new User("Time Was", 451)); 146 | 147 | IntSummaryStatistics trackLengthStats 148 | = users.stream() 149 | //转换为int类型 自动解包 150 | .mapToInt(user -> user.getAge()) 151 | .summaryStatistics(); 152 | 153 | System.out.printf("Max: %d, Min: %d, Ave: %f, Sum: %d", 154 | trackLengthStats.getMax(), 155 | trackLengthStats.getMin(), 156 | trackLengthStats.getAverage(), 157 | trackLengthStats.getSum()); 158 | } 159 | 160 | 161 | /** 162 | * map 循环 163 | */ 164 | @Test 165 | public void countAlbums() { 166 | HashMap map = new HashMap(); 167 | map.put("a", 1); 168 | map.put("b", 2); 169 | map.put("c", 3); 170 | Map countOfAlbums = new HashMap<>(); 171 | map.forEach((k, v) -> { 172 | countOfAlbums.put(k.toString().toUpperCase(), Integer.parseInt(v.toString())); 173 | }); 174 | System.out.print(countOfAlbums.toString()); 175 | } 176 | 177 | /** 178 | * ThreadLocal 的 withInitial 传入一个 supplier对象实例来创建对象 179 | */ 180 | @Test 181 | public void testThreadLocal() { 182 | //通过工厂方式 JVM少加载一个类 183 | ThreadLocal localFormatter = 184 | ThreadLocal.withInitial(() -> new SimpleDateFormat()); 185 | SimpleDateFormat simpleDateFormat = localFormatter.get(); 186 | //System.out.print(simpleDateFormat); 187 | 188 | /** 189 | * AtomicInteger 是一个应对多线程 高并发 实现序列化的integer类型 190 | */ 191 | AtomicInteger threadId = new AtomicInteger(1); 192 | ThreadLocal localId 193 | = ThreadLocal.withInitial(() -> threadId.incrementAndGet()); 194 | int idForThisThread = localId.get(); 195 | System.out.print(idForThisThread); 196 | } 197 | 198 | 199 | /** 200 | * HashSet 排序 201 | */ 202 | @Test 203 | public void hashSetToStreamSorted() { 204 | // BEGIN HASHSET_TO_STREAM_SORTED 205 | Set numbers = new HashSet<>(asList(4, 3, 2, 1)); 206 | 207 | List sameOrder = numbers.stream() 208 | .sorted() 209 | .collect(toList()); 210 | 211 | assertEquals(asList(1, 2, 3, 4), sameOrder); 212 | // END HASHSET_TO_STREAM_SORTED 213 | } 214 | 215 | 216 | /** 217 | * 分类 partitioningBy返回布尔类型值进行分类 218 | */ 219 | @Test 220 | public void bandsAndSolo1() { 221 | List users = asList(new User("Bakai", 524), 222 | new User("Violets for Your Furs", 378), 223 | new User("Time Was", 451)); 224 | Map> collect = users.stream().collect(partitioningBy(user -> user.getAge() == 524)); 225 | System.out.print(collect); 226 | } 227 | 228 | /** 229 | * 分类 groupingBy 数据分类 230 | */ 231 | @Test 232 | public void bandsAndSolo2() { 233 | List users = asList(new User("Bakai", 524), 234 | new User("Violets for Your Furs", 378), 235 | new User("Violets for Your Furs", 378), 236 | new User("Time Was", 451)); 237 | //计数 238 | // Map collect = users.stream().collect(groupingBy(user -> user.getName(), counting())); 239 | //分组 240 | //{451=[User(name=Time Was, age=451)], 378=[User(name=Violets for Your Furs, age=378), User(name=Violets for Your Furs, age=378)], 524=[User(name=Bakai, age=524)]} 241 | Map> collect1 = users.stream() 242 | .collect(groupingBy(User::getAge)); 243 | //{451=[451], 378=[378, 378], 524=[524]} //mapping 将两组中搞到一起 244 | Map> collect2 = users.stream() 245 | .collect(groupingBy(User::getAge, mapping(User::getAge, toList()))); 246 | 247 | System.out.print(collect2); 248 | } 249 | 250 | 251 | /** 252 | * 首先先通过 map 转换到另外一个容器 通过joining 拼接 253 | * joining 拼接 254 | */ 255 | @Test 256 | public void formatArtists() { 257 | List users = asList(new User("Bakai", 524), 258 | new User("Violets for Your Furs", 378), 259 | new User("Violets for Your Furs", 378), 260 | new User("Time Was", 451)); 261 | String result = 262 | users.stream() 263 | .map(User :: getName) 264 | //拼接 265 | .collect(joining(", ", "[", "]")); 266 | System.out.print(result); 267 | } 268 | 269 | } 270 | -------------------------------------------------------------------------------- /src/main/java/lambda/User.java: -------------------------------------------------------------------------------- 1 | package lambda; 2 | 3 | import lombok.Data; 4 | 5 | 6 | @Data 7 | public class User { 8 | 9 | private String name; 10 | private int age; 11 | 12 | public User(String name, int age) { 13 | this.name = name; 14 | this.age = age; 15 | } 16 | 17 | public User() { 18 | 19 | } 20 | } 21 | -------------------------------------------------------------------------------- /src/main/java/lambda/UserArgsInterface.java: -------------------------------------------------------------------------------- 1 | package lambda; 2 | 3 | import java.util.function.BinaryOperator; 4 | 5 | //标记在接口上，函数式接口 是指仅仅只包含一个抽象方法的接口 6 | @FunctionalInterface 7 | public interface UserArgsInterface { 8 | void study(User user); 9 | default void welcome(){ 10 | System.out.print("welcome+++++++++++++++++++"); 11 | } 12 | } 13 | -------------------------------------------------------------------------------- /src/main/java/lambda/UserInterface.java: -------------------------------------------------------------------------------- 1 | package lambda; 2 | 3 | @FunctionalInterface 4 | public interface UserInterface { 5 | void eat(); 6 | 7 | } 8 | -------------------------------------------------------------------------------- /src/main/java/methodReference/MethodReference.java: -------------------------------------------------------------------------------- 1 | package methodReference; 2 | 3 | import org.junit.Test; 4 | 5 | import java.awt.event.ActionListener; 6 | import java.util.Arrays; 7 | import java.util.Comparator; 8 | import java.util.List; 9 | import java.util.function.BinaryOperator; 10 | import java.util.function.Consumer; 11 | import java.util.function.Supplier; 12 | 13 | /** 14 | * @program: jdk8 15 | * @GitHub: https://github.com/ABHSY 16 | * @author: ABHSY.Jason 17 | * @create: 2018-03-31 16:16 18 | * 接口调用 19 | **/ 20 | public class MethodReference { 21 | 22 | @Test 23 | public void test() { 24 | print2(); 25 | System.out.println(); 26 | print3(); 27 | } 28 | 29 | public static void print2() { 30 | List wordList = Arrays.asList("spring", "summer", "autumn", "winter"); 31 | wordList.forEach(word -> System.out.print(word)); 32 | } 33 | 34 | public static void print3() { 35 | List wordList = Arrays.asList("spring", "summer", "autumn", "winter"); 36 | wordList.forEach(System.out::print); 37 | } 38 | 39 | /** 40 | * 静态方法引用 41 | */ 42 | public List sortList1() { 43 | List wordList = Arrays.asList(21, 53, 22); 44 | wordList.sort((w1, w2) -> Integer.compare(w1, w2)); 45 | return wordList; 46 | } 47 | 48 | public List sortList2() { 49 | List wordList = Arrays.asList(21, 53, 22); 50 | wordList.sort(Integer::compare); 51 | return wordList; 52 | } 53 | 54 | public List sortList3() { 55 | List wordList = Arrays.asList(21, 53, 22); 56 | wordList.sort(Comparator.comparingInt(a -> a)); 57 | return wordList; 58 | } 59 | 60 | @Test 61 | public void test2() { 62 | System.out.println(sortList1().toString()); 63 | System.out.println(sortList2().toString()); 64 | System.out.println(sortList3().toString()); 65 | BinaryOperator tComparator = (x, y) -> x + y; 66 | Runnable runnable = () -> System.out.print(1); 67 | ActionListener tConsumer = event -> System.out.print(1); 68 | Comparator tComparator1 = (x, y) -> x + y; 69 | String name = getName(); 70 | Runnable runnable1 = () -> System.out.print(name); 71 | runnable1.run(); 72 | } 73 | 74 | 75 | 76 | 77 | public void test3(){ 78 | String name = getName(); 79 | Runnable runnable = () -> System.out.print(name); 80 | ActionListener actionListener = event -> System.out.print(1); 81 | Runnable runnable1 = () -> { 82 | System.out.print(1); 83 | }; 84 | BinaryOperator binaryOperator = (x, y) -> x + y; 85 | BinaryOperator binaryOperator1 = (Long x,Long y) -> x + y; 86 | 87 | 88 | 89 | } 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | public String getName(){ 101 | return "111"; 102 | } 103 | 104 | @Test 105 | public void test77(){ 106 | ActionListener actionListener = e -> {System.out.print(1);}; 107 | } 108 | 109 | 110 | /** 111 | * 引用对象方法 112 | */ 113 | public String[] sort1() { 114 | String[] words = new String[]{"spring", "summer", "autumn", "winter"}; 115 | Arrays.sort(words, (x, y) -> x.compareToIgnoreCase(y)); 116 | return words; 117 | } 118 | 119 | public String[] sort2() { 120 | String[] words = new String[]{"spring", "summer", "autumn", "winter"}; 121 | Arrays.sort(words, String::compareToIgnoreCase); 122 | return words; 123 | } 124 | 125 | @Test 126 | public void test1() { 127 | System.out.println(Arrays.toString(sort1())); 128 | System.out.println(Arrays.toString(sort2())); 129 | } 130 | 131 | /** 132 | * 构造器引用 133 | */ 134 | @Test 135 | public void construct(){ 136 | StudentFactory studentFactory = new StudentFactory(Student::new); 137 | } 138 | 139 | static class StudentFactory{ 140 | private Supplier supplier; 141 | 142 | StudentFactory(Supplier supplier) { 143 | this.supplier = supplier; 144 | } 145 | } 146 | 147 | 148 | } 149 | -------------------------------------------------------------------------------- /src/main/java/methodReference/Student.java: -------------------------------------------------------------------------------- 1 | package methodReference; 2 | 3 | import lombok.AllArgsConstructor; 4 | import lombok.Data; 5 | import lombok.NoArgsConstructor; 6 | 7 | /** 8 | * @program: jdk8 9 | * @GitHub: https://github.com/ABHSY 10 | * @author: ABHSY.Jason 11 | * @create: 2018-03-31 16:16 12 | * 接口调用 13 | **/ 14 | @Data 15 | @AllArgsConstructor 16 | @NoArgsConstructor 17 | public class Student { 18 | private String name; 19 | private int mathGrade; 20 | private int englishGrade; 21 | 22 | 23 | 24 | public int getGradeCount(){ 25 | return mathGrade + englishGrade; 26 | } 27 | } 28 | -------------------------------------------------------------------------------- /src/main/java/stream/SteamMethod.java: -------------------------------------------------------------------------------- 1 | package stream; 2 | 3 | import methodReference.Student; 4 | import org.junit.Test; 5 | 6 | import java.util.*; 7 | import java.util.stream.Collectors; 8 | import java.util.stream.Stream; 9 | 10 | /** 11 | * @program: jdk8 12 | * @GitHub: https://github.com/ABHSY 13 | * @author: ABHSY.Jason 14 | * @create: 2018-03-31 16:16 15 | * 接口调用 16 | **/ 17 | public class SteamMethod { 18 | private List list = Arrays.asList("111", "112", "131", "4", "5", "6"); 19 | private List data = new ArrayList<>(); 20 | 21 | { 22 | data.add(new Student("xiaoming", 85, 95)); 23 | data.add(new Student("xiaohong", 86, 99)); 24 | data.add(new Student("xiaogang", 100, 100)); 25 | } 26 | 27 | @Test 28 | public void getDistinct() { 29 | 30 | //去重 distinct(非懒加载) 31 | System.out.println(list.stream().distinct().count()); 32 | 33 | 34 | /** 流转换 35 | * 流转换是懒操作的，返回值大多都是Stream，所以才支持链式编程。要想获取转换的数据需要就行聚合操作。通常遇到聚合函数才会开始执行。 36 | **/ 37 | 38 | // map 对于Stream中包含的元素使用给定的转换函数进行转换操作，新生成的Stream只包含转换生成的元素。 39 | 40 | //flatmap 对流进行合并 41 | Stream.of(list, list).flatMap(Collection::stream).forEach(System.out::println); 42 | 43 | 44 | System.out.println("----------------------map 对于Stream中包含的元素使用给定的转换函数进行转换操作"); 45 | System.out.println(list.stream().map(String::toUpperCase).collect(Collectors.toList()).toString()); 46 | 47 | // collect 收集转换后的元素将其转换成map list,同时可以进行分组，排序等一系列操作 48 | System.out.println("----------------------collect 收集转换后的元素将其转换成map list,同时可以进行分组，排序等一系列操作"); 49 | System.out.println(list.stream().map(String::toUpperCase).collect(Collectors.toList()).toString()); 50 | //set 的唯一特性 会让重复元素去掉 51 | System.out.println(list.stream().map(String::toUpperCase).collect(Collectors.toSet())); 52 | // equipmentSetEffectMetaMap = equipmentSetMetaList.stream().collect(Collectors.toMap(EquipmentSetMeta::getId, EquipmentSetEffectMeta -> EquipmentSetEffectMeta)); 53 | 54 | 55 | 56 | //peek 对每一个元素附加处理 57 | System.out.println("---------------------peek 对每一个元素附加处理"); 58 | System.out.println(Stream.of("one", "two", "three", "four") 59 | .filter(e -> e.length() > 3) 60 | .peek(e -> System.out.println("Filtered value: " + e)) 61 | .map(String::toUpperCase) 62 | .peek(e -> System.out.println("Mapped value: " + e)) 63 | .collect(Collectors.toList())); 64 | } 65 | 66 | 67 | @Test 68 | //compareToIgnoreCase 字典排序方式 69 | public void sortedTest(){ 70 | 71 | List collect = list.stream().sorted((x, y) -> x.compareToIgnoreCase(y)).collect(Collectors.toList()); 72 | System.out.print(collect); 73 | System.out.print(list.stream().sorted((x,y)-> new Integer(x).compareTo(new Integer(y))).collect(Collectors.toList())); 74 | 75 | } 76 | 77 | /** 78 | * 聚合操作（非懒加载） 79 | **/ 80 | @Test 81 | public void test3() { 82 | 83 | //max min count 在已有的Stream中获取最大值（需要传入比较器），最小值（需要传入比较器）或者统计总数。 84 | System.out.println("----------------------max min count 在已有的Stream中获取最大值（需要传入比较器），最小值（需要传入比较器）或者统计总数。"); 85 | System.out.println(list.stream().filter(w -> w.length() < 4).count()); 86 | System.out.println(list.stream().max(Comparator.comparingInt(String::length))); 87 | System.out.println(data.stream().min(Comparator.comparingInt(Student::getGradeCount))); 88 | 89 | 90 | //reduce 在一组数据中生成一个值 max min和count因为常用所以单独提取出来了，原本也是属于reduce操作 91 | System.out.println("----------------------reduce 在一组数据中生成一个值 max min和count因为常用所以单独提取出来了，原本也是属于reduce操作"); 92 | //下面是一个累加 93 | int accResult = Stream.of(1, 2, 3, 4) 94 | .reduce(0, (acc, item) -> { 95 | System.out.println("acc : " + acc); 96 | acc += item; 97 | System.out.println("item: " + item); 98 | System.out.println("acc+ : " + acc); 99 | System.out.println("--------"); 100 | return acc; 101 | }); 102 | System.out.println("accResult: " + accResult); 103 | System.out.println("--------"); 104 | //http://blog.csdn.net/io_field/article/details/54971679 105 | 106 | //collect 把Stream中的元素收集到一个容器中去。 107 | System.out.println("----------------------collect 把Stream中的元素收集到一个容器中去。"); 108 | List numList = Arrays.asList(1, 1, null, 2, 3, 4, null, 5, 6, 7, 11, 8, 9, 10); 109 | System.out.println(numList.stream().filter(Objects::nonNull).distinct().sorted().collect(Collectors.toList())); 110 | 111 | //pipeline 对集合的并行操作. fork/join 框架，fork 递归式地分解问题，然后每段并行执行，最终由 join 合并结果，返回最后的值。 112 | list.parallelStream(); 113 | /* 114 | 1. 是否需要并行？ 115 | 2. 任务之间是否是独立的？是否会引起任何竞态条件？ 116 | 3. 结果是否取决于任务的调用顺序？ 117 | */ 118 | /*性能好 119 | ArrayList 、数组或 IntStream.range ，这些数据结构支持随机读取，也就是说它们能轻 120 | 而易举地被任意分解。 121 | 性能一般 122 | HashSet 、 TreeSet ，这些数据结构不易公平地被分解，但是大多数时候分解是可能的。 123 | 性能差 ? 124 | 有些数据结构难于分解，比如，可能要花 O(N) 的时间复杂度来分解问题。其中包括 125 | LinkedList ，对半分解太难了。还有 Streams.iterate 和 BufferedReader.lines ，它们 126 | 长度未知，因此很难预测该在哪里分解。 127 | */ 128 | 129 | //forEach 和 forEachOrdered 的区别：Stream中并行处理集合forEach可能会将原本有序的数据进行打乱，forEachOrdered不会出现，仍然保持有序； 130 | System.out.println("----------------------forEach 和 forEachOrdered 的区别：Stream中并行处理集合forEach可能会将原本有序的数据进行打乱，forEachOrdered不会出现，仍然保持有序；"); 131 | List aa = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8); 132 | aa.stream().parallel().forEach(System.out::print); 133 | System.out.println(); 134 | aa.stream().parallel().forEachOrdered(System.out::print); 135 | } 136 | /** 短路操作*/ 137 | @Test 138 | public void test2(){ 139 | //allMatch 判断Stream中的元素是否全部符合要求 140 | boolean allMatch = Stream.of(1, 2, 3, 4) 141 | .allMatch(integer -> integer > 0); 142 | System.out.println("allMatch: " + allMatch); // 打印结果：allMatch: true 143 | 144 | //anyMatch 判断流中是否有一个符合要求的，有一个则返回true 145 | boolean anyMatch = Stream.of(1, 2, 3, 4) 146 | .anyMatch(integer -> integer > 3); 147 | System.out.println("anyMatch: " + anyMatch); // 打印结果：anyMatch: true 148 | 149 | //noMatch 判断流中是否所有的元素都不符合要求，是的话返回true。 150 | boolean noMatch = Stream.of(1, 2, 3, 4) 151 | .noneMatch(integer -> integer < 0); 152 | System.out.println("noMatch: " + noMatch); // 打印结果：noMatch: true 153 | 154 | //获取第一个元素，如果Stream中的元素没有排序，并行操作中调用可能会随机返回一个。 155 | Optional first = Stream.of(1, 2, 3, 4).findFirst(); 156 | System.out.println(first.get()); 157 | 158 | //获取Stream中的元素，串行操作中默认是选取第一个元素，并行操作中取到的结果不同。 159 | Optional any = Stream.of(1, 2, 3, 4).findAny(); 160 | System.out.println(any.get()); 161 | 162 | //limit 和 sql中的limit类似 截断数据 163 | System.out.println("----------------------limit 和sql中的limit类似 截断数据"); 164 | System.out.println(list.stream().limit(2).collect(Collectors.toList()).toString()); 165 | 166 | //skip 返回一个丢弃原Stream的前N个元素后剩下元素组成的新Stream，如果原Stream中包含的元素个数小于N，那么返回空Stream。 这个是一个非短路操作，因为和limit相关所以放到一起。 167 | System.out.println("----------------------skip 返回一个丢弃原Stream的前N个元素后剩下元素组成的新Stream"); 168 | System.out.println(list.stream().skip(2).collect(Collectors.toList()).toString()); 169 | 170 | 171 | } 172 | 173 | } 174 | --------------------------------------------------------------------------------