生成随机出生日期

Question

我正尝试使用Java程序为我的数据库中的人生成随机出生日期。我将如何做到这一点？

Answer 1

import java.util.GregorianCalendar; 

public class RandomDateOfBirth { 

    public static void main(String[] args) { 

     GregorianCalendar gc = new GregorianCalendar(); 

     int year = randBetween(1900, 2010); 

     gc.set(gc.YEAR, year); 

     int dayOfYear = randBetween(1, gc.getActualMaximum(gc.DAY_OF_YEAR)); 

     gc.set(gc.DAY_OF_YEAR, dayOfYear); 

     System.out.println(gc.get(gc.YEAR) + "-" + (gc.get(gc.MONTH) + 1) + "-" + gc.get(gc.DAY_OF_MONTH)); 

    } 

    public static int randBetween(int start, int end) { 
     return start + (int)Math.round(Math.random() * (end - start)); 
    } 
} 

Answer 2

java.util.Date有constructor接受毫秒自大纪元，和java.util.Random有a method，可以给你的毫秒随机数。你需要为随机值设置一个范围，具体取决于你想要的DOB的范围，但那些应该这样做。

非常大致为：

Random rnd; 
Date dt; 
long ms; 

// Get a new random instance, seeded from the clock 
rnd = new Random(); 

// Get an Epoch value roughly between 1940 and 2010 
// -946771200000L = January 1, 1940 
// Add up to 70 years to it (using modulus on the next long) 
ms = -946771200000L + (Math.abs(rnd.nextLong()) % (70L * 365 * 24 * 60 * 60 * 1000)); 

// Construct a date 
dt = new Date(ms); 

Answer 3

您需要定义一个随机的日期，对吧？

这样做的一种简单方法是，以生成一个新的Date对象，使用long（time in milliseconds since 1st January, 1970）和一个。减去随机long：

new Date(Math.abs(System.currentTimeMillis() - RandomUtils.nextLong())); 

（RandomUtils从Apache的百科全书郎截取）。

当然，这远远不是一个真正的随机日期（例如，你不会得到1970年之前的日期），但我认为它足够满足你的需求。

int year = // generate a year between 1900 and 2010; 
int dayOfYear = // generate a number between 1 and 365 (or 366 if you need to handle leap year); 
Calendar calendar = Calendar.getInstance(); 
calendar.set(Calendar.YEAR, randomYear); 
calendar.set(Calendar.DAY_OF_YEAR, dayOfYear); 
Date randomDoB = calendar.getTime(); 

Answer 4

生成出生的随机日期：

否则，您可以通过使用Calendar类来创建你自己的日期

import java.util.Calendar; 

public class Main { 
    public static void main(String[] args) { 
    for (int i = 0; i < 100; i++) { 
     System.out.println(randomDOB()); 
    } 
    } 

    public static String randomDOB() { 

    int yyyy = random(1900, 2013); 
    int mm = random(1, 12); 
    int dd = 0; // will set it later depending on year and month 

    switch(mm) { 
     case 2: 
     if (isLeapYear(yyyy)) { 
      dd = random(1, 29); 
     } else { 
      dd = random(1, 28); 
     } 
     break; 

     case 1: 
     case 3: 
     case 5: 
     case 7: 
     case 8: 
     case 10: 
     case 12: 
     dd = random(1, 31); 
     break; 

     default: 
     dd = random(1, 30); 
     break; 
    } 

    String year = Integer.toString(yyyy); 
    String month = Integer.toString(mm); 
    String day = Integer.toString(dd); 

    if (mm < 10) { 
     month = "0" + mm; 
    } 

    if (dd < 10) { 
     day = "0" + dd; 
    } 

    return day + '/' + month + '/' + year; 
    } 

    public static int random(int lowerBound, int upperBound) { 
    return (lowerBound + (int) Math.round(Math.random() 
      * (upperBound - lowerBound))); 
    } 

    public static boolean isLeapYear(int year) { 
    Calendar calendar = Calendar.getInstance(); 
    calendar.set(Calendar.YEAR, year); 
    int noOfDays = calendar.getActualMaximum(Calendar.DAY_OF_YEAR); 

    if (noOfDays > 365) { 
     return true; 
    } 

    return false; 
    } 
} 

Answer 5

我学习Scala和结束了谷歌搜索Java解决方案用于选择范围之间的随机日期。我发现this帖子超级有用，这是我的最终解决方案。希望它可以帮助未来的Scala和Java程序员。

import java.sql.Timestamp 

def date_rand(ts_start_str:String = "2012-01-01 00:00:00", ts_end_str:String = "2015-01-01 00:00:00"): String = { 
    val ts_start = Timestamp.valueOf(ts_start_str).getTime() 
    val ts_end = Timestamp.valueOf(ts_end_str).getTime() 
    val diff = ts_end - ts_start 
    println(diff) 
    val ts_rand = new Timestamp(ts_start + (Random.nextFloat() * diff).toLong) 
    return ts_rand.toString 
}           //> date_rand: (ts_start_str: String, ts_end_str: String)String 

println(date_rand())      //> 94694400000 
               //| 2012-10-28 18:21:13.216 

println(date_rand("2001-01-01 00:00:00", "2001-01-01 00:00:00")) 
               //> 0 
               //| 2001-01-01 00:00:00.0 
println(date_rand("2001-01-01 00:00:00", "2010-01-01 00:00:00")) 
               //> 283996800000 
               //| 2008-02-16 23:15:48.864     //> 2013-12-21 08:32:16.384 

Answer 6

片段为Java 8基于溶液：

Random random = new Random(); 
int minDay = (int) LocalDate.of(1900, 1, 1).toEpochDay(); 
int maxDay = (int) LocalDate.of(2015, 1, 1).toEpochDay(); 
long randomDay = minDay + random.nextInt(maxDay - minDay); 

LocalDate randomBirthDate = LocalDate.ofEpochDay(randomDay); 

System.out.println(randomBirthDate); 

注：这生成1Jan1900（含）和1Jan2015（不包括）之间的随机日期。

注意：它是基于epoch days，即天相1Jan1970（EPOCH） - 正EPOCH后的意义，EPOCH之前否定意义

---

您还可以创建一个小工具类：

public class RandomDate { 
    private final LocalDate minDate; 
    private final LocalDate maxDate; 
    private final Random random; 

    public RandomDate(LocalDate minDate, LocalDate maxDate) { 
     this.minDate = minDate; 
     this.maxDate = maxDate; 
     this.random = new Random(); 
    } 

    public LocalDate nextDate() { 
     int minDay = (int) minDate.toEpochDay(); 
     int maxDay = (int) maxDate.toEpochDay(); 
     long randomDay = minDay + random.nextInt(maxDay - minDay); 
     return LocalDate.ofEpochDay(randomDay); 
    } 

    @Override 
    public String toString() { 
     return "RandomDate{" + 
       "maxDate=" + maxDate + 
       ", minDate=" + minDate + 
       '}'; 
    } 
} 

，并使用它像这样：

RandomDate rd = new RandomDate(LocalDate.of(1900, 1, 1), LocalDate.of(2010, 1, 1)); 
System.out.println(rd.nextDate()); 
System.out.println(rd.nextDate()); // birthdays ad infinitum 

Answer 7

您将以dd/mm/yyyy得到日期
您可以使用数学。随机（）函数，就像我在下面

在这里完成我们生成3个随机数字1至31,1至12,1990至2016年和连接中的“/”他们

之间

public static String getRandomJoinDate() 
    { 
     String date=""; 
     int yearBegin=1990; 
     int yearEnd=2016-yearBegin; 

     date=""+(1 + (int)(Math.random() * 31)+"/"+(1 + (int)(Math.random() * 12)+"/"+(yearBegin + (int)(Math.random() * yearEnd)))); 
     return date; 
    } 

进一步了解下面的Math.random（）链接可以帮助
Math.random() explained

Answer 8

您可以检出randomizer随机数据generation.This库有助于下面的示例代码从给定的模型class.Checkout创建随机数据。

public class Person { 

    @DateValue(from = "01 Jan 1990",to = "31 Dec 2002" , customFormat = "dd MMM yyyy") 
    String dateOfBirth; 

} 

//Generate random 100 Person(Model Class) object 
Generator<Person> generator = new Generator<>(Person.class); 
List<Person> persons = generator.generate(100);       

由于有很多是使用注解访问，您也可以创建自定义数据generator.I建议你去通过提供的库页的文档，内置的数据发生器。

Answer 9

看看这个方法：

public static Date dateRandom(int initialYear, int lastYear) { 
    if (initialYear > lastYear) { 
     int year = lastYear; 
     lastYear = initialYear; 
     initialYear = year; 
    } 

    Calendar cInitialYear = Calendar.getInstance(); 
    cInitialYear.set(Calendar.YEAR, 2015); 
    long offset = cInitialYear.getTimeInMillis(); 

    Calendar cLastYear = Calendar.getInstance(); 
    cLastYear.set(Calendar.YEAR, 2016); 
    long end = cLastYear.getTimeInMillis(); 

    long diff = end - offset + 1; 
    Timestamp timestamp = new Timestamp(offset + (long) (Math.random() * diff)); 
    return new Date(timestamp.getTime()); 
} 

Answer 10

如果你不介意加入一个新的图书馆，以你的代码，你可以使用MockNeat（免责声明：我是作者之一）。

MockNeat mock = MockNeat.threadLocal(); 

// Generates a random date between [1970-1-1, NOW) 
LocalDate localDate = mock.localDates().val(); 
System.out.println(localDate); 

// Generates a random date in the past 
// but beore 1987-1-30 
LocalDate min = LocalDate.of(1987, 1, 30); 
LocalDate past = mock.localDates().past(min).val(); 
System.out.println(past); 

LocalDate max = LocalDate.of(2020, 1, 1); 
LocalDate future = mock.localDates().future(max).val(); 
System.out.println(future); 

// Generates a random date between 1989-1-1 and 1993-1-1 
LocalDate start = LocalDate.of(1989, 1, 1); 
LocalDate stop = LocalDate.of(1993, 1, 1); 
LocalDate between = mock.localDates().between(start, stop).val(); 
System.out.println(between); 

Answer 11

对于Java8 - > Assumming出生的数据必须是最新的前一天：

import java.time.LocalDate; 
import java.time.LocalTime; 
import java.time.Period; 
import java.time.temporal.ChronoUnit; 
import java.util.Random; 

public class RandomDate { 

    public static LocalDate randomBirthday() { 
     return LocalDate.now().minus(Period.ofDays((new Random().nextInt(365 * 70)))); 
    } 

    public static void main(String[] args) { 
     System.out.println("randomDate: " + randomBirthday()); 
    } 
} 

Answer 12

我认为这将这样的伎俩：

public static void main(String[] args) { 
    Date now = new Date(); 
    long sixMonthsAgo = (now.getTime() - 15552000000l); 
    long today = now.getTime(); 

    for(int i=0; i<10; i++) { 
     long ms = ThreadLocalRandom.current().nextLong(sixMonthsAgo, today); 

     Date date = new Date(ms); 

     System.out.println(date.toString()); 
    } 

} 

Answer 13

如果你不介意一个第三方库，Utils库有一个RandomDateUtils，它会生成随机java.util.Dates以及来自Java 8的所有日期，时间，时刻和持续时间date and time API

LocalDate birthDate = RandomDateUtils.randomPastLocalDate(); 
LocalDate today = LocalDate.now(); 
LocalDate under18YearsOld = RandomDateUtils.randomLocalDate(today.minus(18, YEARS), today); 
LocalDate over18YearsOld = RandomDateUtils.randomLocalDateBefore(today.minus(18, YEARS)); 

它是在Maven中央仓库在：

<dependency> 
    <groupId>com.github.rkumsher</groupId> 
    <artifactId>utils</artifactId> 
    <version>1.0</version> 
</dependency>