Add concept datetime and exercise booking-up-for-beauty (#2590)

* Add concept exercise booking-up-for-beauty

* Add datetime concept skeleton

* Add concept and exercise to config.json

* Fix Markdown lint errors

* Add copy for datetime concept

* Add datetime concept to existing practice exercises

* Rename concept to "Date-Time"

* Shorten concept introduction a bit

concepts/datetime/.meta/config.json

@@ -0,0 +1,5 @@
+{
+  "blurb": "There are several classes in Java to work with dates and time.",
+  "authors": ["sanderploegsma"],
+  "contributors": []
+}

concepts/datetime/about.md

@@ -0,0 +1,124 @@
+# About
+
+The `java.time` package introduced in Java 8 contains several classes to work with dates and time.
+
+## `LocalDate`
+
+The [`java.time.LocalDate`][localdate-docs] class represents a date without a time-zone in the [ISO-8601 calendar system][iso-8601], such as `2007-12-03`:
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+```
+
+Dates can be compared to other dates:
+
+```java
+LocalDate date1 = LocalDate.of(2007, 12, 3);
+LocalDate date2 = LocalDate.of(2007, 12, 4);
+
+date1.isBefore(date2);
+// => true
+
+date1.isAfter(date2);
+// => false
+```
+
+A `LocalDate` instance has getters to retrieve time portions from it:
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+
+date.getYear();
+// => 2007
+
+date.getMonthValue();
+// => 12
+
+date.getDayOfMonth();
+// => 3
+```
+
+A `LocalDate` instance has methods to add time units to it.
+
+```exercism/note
+These methods return a _new_ `LocalDate` instance and do not update the existing instance, as the `LocalDate` class is immutable.
+```
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+
+date.addDays(3);
+// => 2007-12-06
+
+date.addMonths(1);
+// => 2008-01-03
+
+date.addYears(1);
+// => 2008-12-03
+```
+
+## `LocalDateTime`
+
+The [`java.time.LocalDateTime`][localdatetime-docs] class represents a date-time without a time-zone in the [ISO-8601 calendar system][iso-8601], such as `2007-12-03T10:15:30`:
+
+```java
+LocalDateTime datetime = LocalDateTime.of(2007, 12, 3, 10, 15, 30);
+
+datetime.getYear();
+// => 2007
+
+datetime.getMonthValue();
+// => 12
+
+datetime.getDayOfMonth();
+// => 3
+
+datetime.getHours();
+// => 10
+
+datetime.getMinutes();
+// => 15
+
+datetime.getSeconds();
+// => 30
+```
+
+Like the `LocalDate` class, a `LocalDateTime` instance has the same methods to compare to other `LocalDateTime`s and to add time units to it.
+
+It is also possible to convert a `LocalDate` instance into a `LocalDateTime`:
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+LocalDateTime datetime = date.atTime(10, 15, 30);
+datetime.toString();
+// => "2007-12-03T10:15:30"
+```
+
+## Formatting datetimes
+
+Both `LocalDate` and `LocalDateTime` use the [ISO-8601][iso-8601] standard notation when converting from and to a `String`.
+
+```java
+LocalDateTime datetime = LocalDateTime.of(2007, 12, 3, 10, 15, 30);
+LocalDateTime parsed = LocalDateTime.parse("2007-12-03T10:15:30");
+
+datetime.isEqual(parsed);
+// => true
+```
+
+Attempting to parse a `LocalDate` or `LocalDateTime` from a `String` like this using a different format is not possible.
+Instead, to format dates using a custom format, you should use the [`java.time.format.DateTimeFormatter`][datetimeformatter-docs]:
+
+```java
+DateTimeFormatter parser = DateTimeFormatter.ofPattern("dd/MM/yyyy");
+LocalDate date = LocalDate.parse("03/12/2007", formatter);
+
+DateTimeFormatter printer = DateTimeFormatter.ofPattern("MMMM d, yyyy");
+printer.format(date);
+// => "December 3, 2007"
+```
+
+[iso-8601]: https://en.wikipedia.org/wiki/ISO_8601
+[localdate-docs]: https://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html
+[localdatetime-docs]: https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html
+[datetimeformatter-docs]: https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html

concepts/datetime/introduction.md

@@ -0,0 +1,89 @@
+# Introduction
+
+The `java.time` package introduced in Java 8 contains several classes to work with dates and time.
+
+## `LocalDate`
+
+The `java.time.LocalDate` class represents a date without a time-zone in the [ISO-8601 calendar system][iso-8601], such as `2007-12-03`:
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+```
+
+Dates can be compared to other dates:
+
+```java
+LocalDate date1 = LocalDate.of(2007, 12, 3);
+LocalDate date2 = LocalDate.of(2007, 12, 4);
+
+date1.isBefore(date2);
+// => true
+
+date1.isAfter(date2);
+// => false
+```
+
+A `LocalDate` instance has getters to retrieve time portions from it:
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+
+date.getDayOfMonth();
+// => 3
+```
+
+A `LocalDate` instance has methods to add time units to it:
+
+```exercism/note
+These methods return a _new_ `LocalDate` instance and do not update the existing instance, as the `LocalDate` class is immutable.
+```
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+
+date.addDays(3);
+// => 2007-12-06
+```
+
+## `LocalDateTime`
+
+The `java.time.LocalDateTime` class represents a date-time without a time-zone in the [ISO-8601 calendar system][iso-8601], such as `2007-12-03T10:15:30`:
+
+```java
+LocalDateTime datetime = LocalDateTime.of(2007, 12, 3, 10, 15, 30);
+```
+
+You can convert a `LocalDate` instance into a `LocalDateTime`:
+
+```java
+LocalDate date = LocalDate.of(2007, 12, 3);
+LocalDateTime datetime = date.atTime(10, 15, 30);
+datetime.toString();
+// => "2007-12-03T10:15:30"
+```
+
+## Formatting datetimes
+
+Both `LocalDate` and `LocalDateTime` use the [ISO-8601][iso-8601] standard notation when converting from and to a `String`.
+
+```java
+LocalDateTime datetime = LocalDateTime.of(2007, 12, 3, 10, 15, 30);
+LocalDateTime parsed = LocalDateTime.parse("2007-12-03T10:15:30");
+
+datetime.isEqual(parsed);
+// => true
+```
+
+Attempting to parse a `LocalDate` or `LocalDateTime` from a `String` like this using a different format is not possible.
+Instead, to format dates using a custom format, you should use the `java.time.format.DateTimeFormatter`:
+
+```java
+DateTimeFormatter parser = DateTimeFormatter.ofPattern("dd/MM/yyyy");
+LocalDate date = LocalDate.parse("03/12/2007", formatter);
+
+DateTimeFormatter printer = DateTimeFormatter.ofPattern("MMMM d, yyyy");
+printer.format(date);
+// => "December 3, 2007"
+```
+
+[iso-8601]: https://en.wikipedia.org/wiki/ISO_8601

concepts/datetime/links.json

@@ -0,0 +1,14 @@
+[
+  {
+    "url": "https://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html",
+    "description": "LocalDate documentation"
+  },
+  {
+    "url": "https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html",
+    "description": "LocalDateTime documentation"
+  },
+  {
+    "url": "https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html",
+    "description": "DateTimeFormatter documentation"
+  }
+]

config.json

@@ -259,6 +259,18 @@
           "numbers",
           "strings"
         ]
+      },
+      {
+        "slug": "booking-up-for-beauty",
+        "name": "Booking Up For Beauty",
+        "uuid": "6a514e9a-ed92-4e01-8af7-579d659415a4",
+        "concepts": [
+          "datetime"
+        ],
+        "prerequisites": [
+          "numbers",
+          "strings"
+        ]
       }
     ],
     "practice": [
@@ -303,9 +315,10 @@
         "name": "Gigasecond",
         "uuid": "bf1641c8-dc0d-4d38-9cfe-b4c132ea3553",
         "practices": [
-          "numbers"
+          "datetime"
         ],
         "prerequisites": [
+          "datetime",
           "numbers"
         ],
         "difficulty": 3
@@ -885,10 +898,11 @@
         "name": "Meetup",
         "uuid": "602511d5-7e89-4def-b072-4dd311816810",
         "practices": [
-          "enums",
-          "for-loops"
+          "datetime",
+          "enums"
         ],
         "prerequisites": [
+          "datetime",
           "enums"
         ],
         "difficulty": 7
@@ -1995,10 +2009,12 @@
         "name": "Ledger",
         "uuid": "6597548e-176d-49c6-be33-789f4c43867a",
         "practices": [
+          "datetime",
           "strings"
         ],
         "prerequisites": [
           "classes",
+          "datetime",
           "strings"
         ],
         "difficulty": 5
@@ -2101,6 +2117,11 @@
       "slug": "constructors",
       "name": "Constructors"
     },
+    {
+      "uuid": "16e1b053-f99d-410e-8b3c-054e764da953",
+      "slug": "datetime",
+      "name": "Date-Time"
+    },
     {
       "uuid": "cb753863-b7c1-4ff6-adeb-ae9a1f39deca",
       "slug": "enums",

exercises/concept/booking-up-for-beauty/.docs/hints.md

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+# Hints
+
+## 1. Parse appointment date
+
+- The `LocalDateTime` class has a method to [parse][localdatetime-parse] a `String` to a `LocalDateTime`.
+- Use a [`DateTimeFormatter`][datetimeformatter-docs] with a custom pattern to parse a non-standard date/time format.
+
+## 2. Check if an appointment has already passed
+
+- `LocalDateTime` instances have [methods][localdatetime-methods] to compare them to other `LocalDateTime`s.
+- There is a [method][localdatetime-methods] to retrieve the current date and time.
+
+## 3. Check if appointment is in the afternoon
+
+- Accessing the time portion of a `LocalDateTime` instance can de done through one of its [methods][localdatetime-methods].
+
+## 4. Describe the time and date of the appointment
+
+- Use a [`DateTimeFormatter`][datetimeformatter-docs] with a custom pattern to format the `LocalDateTime`.
+- The tests are running as if running on a machine in the United States, so make sure that the formatter [uses the correct locale][datetimeformatter-ofpattern-with-locale].
+
+## 5. Return the anniversary date
+
+- The `LocalDate` class has a [method][localdate-methods] to retrieve the current date.
+- Accessing the year of a `LocalDate` instance can de done through one of its [methods][localdate-methods].
+
+[localdate-methods]: https://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html
+[localdatetime-methods]: https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html
+[localdatetime-parse]: https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html#parse-java.lang.CharSequence-java.time.format.DateTimeFormatter-
+[datetimeformatter-docs]: https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html
+[datetimeformatter-ofpattern-with-locale]: https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html#ofPattern-java.lang.String-java.util.Locale-

exercises/concept/booking-up-for-beauty/.docs/instructions.md

@@ -0,0 +1,53 @@
+# Instructions
+
+In this exercise you'll be working on an appointment scheduler for a beauty salon in New York that opened on September 15th in 2012.
+
+## 1. Parse appointment date
+
+Implement the `AppointmentScheduler.schedule()` method to parse a textual representation of an appointment date into the corresponding `LocalDateTime`:
+
+```java
+AppointmentScheduler scheduler = new AppointmentScheduler();
+scheduler.schedule("7/25/2019 13:45:00");
+// => LocalDateTime.of(2019, 7, 25, 13, 45, 0)
+```
+
+## 2. Check if an appointment has already passed
+
+Implement the `AppointmentScheduler.hasPassed()` method that takes an appointment date and checks if the appointment was somewhere in the past:
+
+```java
+AppointmentScheduler scheduler = new AppointmentScheduler();
+scheduler.hasPassed(LocalDateTime.of(1999, 12, 31, 9, 0, 0));
+// => true
+```
+
+## 3. Check if appointment is in the afternoon
+
+Implement the `AppointmentScheduler.isAfternoonAppointment()` method that takes an appointment date and checks if the appointment is in the afternoon (>= 12:00 and < 18:00):
+
+```java
+AppointmentScheduler scheduler = new AppointmentScheduler();
+scheduler.isAfternoonAppointment(LocalDateTime.of(2019, 03, 29, 15, 0, 0))
+// => true
+```
+
+## 4. Describe the time and date of the appointment
+
+Implement the `AppointmentScheduler.getDescription()` method that takes an appointment date and returns a description of that date and time:
+
+```java
+AppointmentScheduler scheduler = new AppointmentScheduler();
+scheduler.getDescription(LocalDateTime.of(2019, 03, 29, 15, 0, 0))
+// => "You have an appointment on Friday, March 29, 2019, at 3:00 PM."
+```
+
+## 5. Return the anniversary date
+
+Implement the `AppointmentScheduler.getAnniversaryDate()` method that returns this year's anniversary date, which is September 15th:
+
+```java
+AppointmentScheduler scheduler = new AppointmentScheduler();
+scheduler.getAnniversaryDate()
+// => LocalDate.of(2023, 9, 15)
+```