From 7033900d839d6651f949f7dbe91c9e77175c9c9d Mon Sep 17 00:00:00 2001
From: "Dr. Martin Goik" <goik@hdm-stuttgart.de>
Date: Fri, 12 Oct 2018 17:04:28 +0200
Subject: [PATCH] Implementation hints
---
.../mi/javastreams/Java8FunctionalTest.java | 99 ++++++---
.../mi/javastreams/RosterTest.java | 202 ++++++++----------
.../hdm_stuttgart/mi/javastreams/Student.java | 49 +----
.../mi/javastreams/Java8FunctionalTest.java | 37 +++-
4 files changed, 182 insertions(+), 205 deletions(-)
diff --git a/P/Sda1/Streams/Solution/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java b/P/Sda1/Streams/Solution/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java
index 39a44d258..2e9430d4c 100644
--- a/P/Sda1/Streams/Solution/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java
+++ b/P/Sda1/Streams/Solution/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java
@@ -11,38 +11,47 @@ import java.util.stream.Collectors;
import org.hamcrest.Matchers;
import org.junit.Assert;
+import org.junit.FixMethodOrder;
import org.junit.Test;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import de.hdm_stuttgart.mi.javastreams.Student.Sex;
+import org.junit.runners.MethodSorters;
/**
* Testing functional queries.
*/
+@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class Java8FunctionalTest {
- final List<Student> roster = Student.createRoster();
+ static private final List<Student> students = ImmutableList.of(
+ new Student("Fred", 2, Student.Sex.MALE, "fred@example.com")
+ ,new Student("Jane", 1, Student.Sex.FEMALE, "jane@kiv.de")
+ ,new Student("George", 4, Student.Sex.MALE, "george@math.edu")
+ ,new Student("Bob", 2, Student.Sex.MALE, "bob@uk.edu")
+ ,new Student("Kim", 2, Student.Sex.FEMALE, "wilde@serious.de")
+ );
- /**
- * Order all male students by email and create a list of their respective names
- * in that order eliminating possible duplicates:
- *
- * "Bob", 2, Student.Sex.MALE, "bob@uk.edu"
- * "Fred", 2, Student.Sex.MALE, "fred@example.com"
- * "George", 4, Student.Sex.MALE, "george@math.edu"
- * "Jane", 1, Student.Sex.FEMALE, "jane@kiv.de"
- * "Kim", 2, Student.Sex.FEMALE, "wilde@serious.de"
- *
- * ==> {"Bob", "Fred", "George"}
- *
- */
+ /**
+ * <p>Order all male students by email and create a {@code List<String>} of their respective
+ * names alphabetically ordered eliminating possible duplicates. Implementation hints:</p>
+ *
+ * <pre
+ * >"Fred", 2, Student.Sex.MALE, "fred@example.com"
+ * "Jane", 1, Student.Sex.FEMALE, "jane@kiv.de"
+ * "George", 4, Student.Sex.MALE, "george@math.edu"
+ * "Bob", 2, Student.Sex.MALE, "bob@uk.edu"
+ * "Kim", 2, Student.Sex.FEMALE, "wilde@serious.de"</pre>
+ *
+ * <p>Result: {"Bob", "Fred", "George"}</p>
+ */
@Test
public void allMaleDistinctNameOrderedByEmail() {
final List<String> emails =
- roster.parallelStream().
+ students.parallelStream().
filter(s -> s.gender == Sex.MALE).
sorted((s1, s2) -> s1.getEmailAddress().compareTo(s2.getEmailAddress())).
map(Student::getName).
@@ -57,18 +66,42 @@ public class Java8FunctionalTest {
);
}
- /**
- * Summing students' marks having a German email address:
- *
- * "Jane", 1, Student.Sex.FEMALE, "jane@kiv.de"
- * "Kim", 2, Student.Sex.FEMALE, "wilde@serious.de"
- *
- */
+ /**
+ * <p>Summing up all students' marks having a German email address.</p>
+ *
+ * <dl>
+ *
+ * <dt>List of all students having a german E-mail:</dt>
+ * <dd>
+ * <ul>
+ * <li><code>{"Jane", 1, Student.Sex.FEMALE, "jane@kiv.de"}</code></li>
+ * <li><code>{"Kim", 2, Student.Sex.FEMALE, "wilde@serious.de"}</code></li>
+ * </ul>
+ * </dd>
+ *
+ * <dt>Summing up related marks:</dt>
+ * <dd>Expected value: 1 + 2 == 3</dd>
+ * </dl>
+ *
+ * <p>Implementation hint: Process a stream of Student instances by:</p>
+ *
+ * <ol>
+ * <li>Filter students having a german email.</li>
+ * <li>Map objects to int.</li>
+ * <li>Provide a suitable
+ * <a href="https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html#reduce"
+ * >reduce operation</a>. You may safely assume the existence of at least one Student.</li>
+ * </ol>
+ *
+ * <p>You may want to read
+ * <a href="https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html#reduce"
+ * >https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html#reduce</a>.</p>
+ */
@Test
public void markSumAllStudentsMarksHavingEmail_Dot_de() {
Assert.assertEquals(
3, //Expected marks sum 3 == 1 + 2
- roster.parallelStream()
+ students.parallelStream()
.filter(p -> p.emailAddress.endsWith(".de")) // Jane and Kim
.mapToInt(Student::getMark)
.reduce(0, (a, b) -> a + b)
@@ -76,8 +109,8 @@ public class Java8FunctionalTest {
}
/**
- * A comma separated string containing all students' alphabetically ordered
- * email addresses:
+ * <p>A comma separated string containing all students' alphabetically ordered
+ * email addresses:</p>
*
* "bob@uk.edu, fred@example.com, george@math.edu, ..."
*
@@ -88,7 +121,7 @@ public class Java8FunctionalTest {
Assert.assertEquals(
"bob@uk.edu, fred@example.com, george@math.edu, jane@kiv.de, wilde@serious.de",
- roster.parallelStream().
+ students.parallelStream().
map(Student::getEmailAddress).
sorted().
collect(new CsvCollector(", ")) // Using ", " as separator string.
@@ -110,7 +143,7 @@ public class Java8FunctionalTest {
Assert.assertEquals(
"bob@uk.edu, fred@example.com, george@math.edu, jane@kiv.de, wilde@serious.de",
- roster.parallelStream().
+ students.parallelStream().
map(Student::getEmailAddress).
sorted().
collect
@@ -134,7 +167,7 @@ public class Java8FunctionalTest {
public void averageMarkFemaleStudents() {
final OptionalDouble femaleAverage =
- roster.parallelStream().
+ students.parallelStream().
filter(s -> s.gender == Sex.FEMALE).
mapToInt(Student::getMark).
average();
@@ -161,7 +194,7 @@ public class Java8FunctionalTest {
public void studentNamesBySex() {
final Map<Student.Sex, List<String>> studentnamesBySex =
- roster
+ students
.parallelStream()
.collect(
Collectors.groupingBy(
@@ -187,14 +220,14 @@ public class Java8FunctionalTest {
* Marking frequencies:
*
* Mark 1: "Jane" --- 1 student
- * Mark 2: "Fred", "Bob", "Kim" --> 3 students
- * Mark 4: "George" --> 1 student
+ * Mark 2: "Fred", "Bob", "Kim" --- 3 students
+ * Mark 4: "George" --- 1 student
*
*/
@Test
public void markingFrequencies() {
final Map<Integer, Integer> frequencyByMark =
- roster
+ students
.parallelStream()
.collect(
Collectors.groupingBy(
@@ -229,7 +262,7 @@ public class Java8FunctionalTest {
public void studentnamessByMark() {
final Map<Integer, List<String>> namesByMark =
- roster
+ students
.parallelStream()
.collect(
Collectors.groupingBy(
diff --git a/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/RosterTest.java b/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/RosterTest.java
index 4bee36942..09b4b611c 100644
--- a/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/RosterTest.java
+++ b/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/RosterTest.java
@@ -1,5 +1,8 @@
package de.hdm_stuttgart.mi.javastreams;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Function;
@@ -10,111 +13,108 @@ import java.util.function.Predicate;
* https://docs.oracle.com/javase/tutorial/java/javaOO/examples/Person.java
* and
* https://docs.oracle.com/javase/tutorial/java/javaOO/examples/RosterTest.java
- *
*/
public class RosterTest {
-
- static final List<Student> rosterInstance = Student.createRoster();
-
+
+ static final List<Student> students = ImmutableList.of(
+ new Student("Fred", 2, Student.Sex.MALE, "fred@example.com")
+ ,new Student("Jane", 1, Student.Sex.FEMALE, "jane@kiv.de")
+ ,new Student("George", 4, Student.Sex.MALE, "george@math.edu")
+ ,new Student("Bob", 2, Student.Sex.MALE, "bob@uk.edu")
+ ,new Student("Kim", 2, Student.Sex.FEMALE, "wilde@serious.de")
+ );
+
+
interface CheckStudent {
boolean test(Student p);
}
- // Approach 1: Create Methods that Search for Persons that Match One
- // Characteristic
-
/**
+ * Approach 1: Create Methods that searching for Persons matching one characteristic
+ *
* @param roster
* @param mark
*/
- public static void printPersonsOlderThan(List<Student> roster, int mark) {
- for (Student p : roster) {
+ public static void printPersonsOlderThan(final List<Student> roster, final int mark) {
+ for (final Student p : roster) {
if (p.getMark()>= mark) {
p.print();
}
}
}
- // Approach 2: Create More Generalized Search Methods
-
/**
+ * Approach 2: Create more generalized search methods
+ *
* @param roster
* @param low
* @param high
*/
- public static void printPersonsWithinMarkRange(
- List<Student> roster, int low, int high) {
- for (Student p : roster) {
+ public static void printPersonsWithinMarkRange(final List<Student> roster, final int low, final int high) {
+ for (final Student p : roster) {
if (low <= p.getMark() && p.getMark() <= high) {
p.print();
}
}
}
- // Approach 3: Specify Search Criteria Code in a Local Class
- // Approach 4: Specify Search Criteria Code in an Anonymous Class
- // Approach 5: Specify Search Criteria Code with a Lambda Expression
-
/**
+ * Approach 3: Specify search criteria in a local class
+ * Approach 4: Specify search criteria by an anonymous class
+ * Approach 5: Specify search criteria by lambda expression
+ *
* @param roster
* @param tester
*/
- public static void printPersons(
- List<Student> roster, CheckStudent tester) {
- for (Student p : roster) {
+ public static void printPersons(final List<Student> roster, final CheckStudent tester) {
+ for (final Student p : roster) {
if (tester.test(p)) {
p.print();
}
}
}
- // Approach 6: Use Standard Functional Interfaces with Lambda Expressions
-
/**
+ * Approach 6: Use standard functional interfaces employing lambda expressions.
+ *
* @param roster
* @param tester
*/
- public static void printPersonsWithPredicate(
- List<Student> roster, Predicate<Student> tester) {
- for (Student p : roster) {
+ public static void printPersonsWithPredicate(final List<Student> roster, final Predicate<Student> tester) {
+ for (final Student p : roster) {
if (tester.test(p)) {
p.print();
}
}
}
- // Approach 7: Use Lambda Expressions Throughout Your Application
-
/**
+ * Approach 7: Use lambda expressions throughout your application
+ *
* @param roster
* @param tester
* @param block
*/
- public static void processPersons(
- List<Student> roster,
- Predicate<Student> tester,
- Consumer<Student> block) {
- for (Student p : roster) {
+ public static void processPersons(final List<Student> roster, final Predicate<Student> tester,
+ final Consumer<Student> block) {
+ for (final Student p : roster) {
if (tester.test(p)) {
block.accept(p);
}
}
}
- // Approach 7, second example
-
/**
+ * Approach 7, second example
+ *
* @param roster
* @param tester
* @param mapper
* @param block
*/
- public static void processPersonsWithFunction(
- List<Student> roster,
- Predicate<Student> tester,
- Function<Student, String> mapper,
- Consumer<String> block) {
- for (Student p : roster) {
+ public static void processPersonsByFunction(final List<Student> roster, final Predicate<Student> tester,
+ final Function<Student, String> mapper, final Consumer<String> block) {
+ for (final Student p : roster) {
if (tester.test(p)) {
String data = mapper.apply(p);
block.accept(data);
@@ -122,25 +122,22 @@ public class RosterTest {
}
}
- // Approach 8: Use Generics More Extensively
-
/**
+ * Approach 8: Use Generics more extensively
+ *
* @param source
* @param tester
* @param mapper
* @param block
*/
- public static <X, Y> void processElements(
- Iterable<X> source,
- Predicate<X> tester,
- Function<X, Y> mapper,
- Consumer<Y> block) {
- for (X p : source) {
- if (tester.test(p)) {
- Y data = mapper.apply(p);
- block.accept(data);
- }
+ public static <X, Y> void processElements( final Iterable<X> source, final Predicate<X> tester,
+ final Function<X, Y> mapper, final Consumer<Y> block) {
+ for (final X p : source) {
+ if (tester.test(p)) {
+ Y data = mapper.apply(p);
+ block.accept(data);
}
+ }
}
/**
@@ -148,27 +145,21 @@ public class RosterTest {
*/
public static void main(String... args) {
- for (Student p : rosterInstance) {
+ System.out.println("All student records:");
+ for (final Student p : students) {
p.print();
}
- // Approach 1: Create Methods that Search for Persons that Match One
- // Characteristic
-
- System.out.println("Persons older than 20:");
- printPersonsOlderThan(rosterInstance, 20);
- System.out.println();
-
- // Approach 2: Create More Generalized Search Methods
-
- System.out.println("Persons between the ages of 14 and 30:");
- printPersonsWithinMarkRange(rosterInstance, 14, 30);
- System.out.println();
+ // Approach 1: Create methods searching for students matching one characteristic
+ System.out.println("\nApproach 1: Persons older than 20:");
+ printPersonsOlderThan(students, 20);
- // Approach 3: Specify Search Criteria Code in a Local Class
-
- System.out.println("Persons who are eligible for Selective Service:");
+ // Approach 2: Create more generalized search methods
+ System.out.println("\nApproach 2: Persons between 14 and 30 of age:");
+ printPersonsWithinMarkRange(students, 14, 30);
+ // Approach 3: Specify search criteria by a local class
+ System.out.println("\nApproach 3: Persons eligible for selective service:");
class CheckStudentEligibleForSelectiveService implements CheckStudent {
@Override
public boolean test(Student p) {
@@ -177,23 +168,16 @@ public class RosterTest {
&& p.getMark() <= 3;
}
}
+ printPersons(students, new CheckStudentEligibleForSelectiveService());
- printPersons(
- rosterInstance, new CheckStudentEligibleForSelectiveService());
-
-
- System.out.println();
-
- // Approach 4: Specify Search Criteria Code in an Anonymous Class
-
- System.out.println("Persons who are eligible for Selective Service " +
+ // Approach 4: Specify search criteria code in an anonymous class
+ System.out.println("\nApproach 4: Persons eligible for selective service " +
"(anonymous class):");
-
printPersons(
- rosterInstance,
+ students,
new CheckStudent() {
@Override
- public boolean test(Student p) {
+ public boolean test(final Student p) {
return p.getSex() == Student.Sex.MALE
&& p.getMark() >= 2
&& p.getMark() <= 3;
@@ -201,59 +185,46 @@ public class RosterTest {
}
);
- System.out.println();
-
- // Approach 5: Specify Search Criteria Code with a Lambda Expression
-
- System.out.println("Persons who are eligible for Selective Service " +
+ // Approach 5: Specify search criteria by lambda expression
+ System.out.println("\nApproach 5: Persons eligible for selective service " +
"(lambda expression):");
printPersons(
- rosterInstance,
+ students,
(Student p) -> p.getSex() == Student.Sex.MALE
&& p.getMark() >= 2
&& p.getMark() <= 3
);
- System.out.println();
-
- // Approach 6: Use Standard Functional Interfaces with Lambda
- // Expressions
-
- System.out.println("Persons who are eligible for Selective Service " +
+ // Approach 6: Use Standard functional interfaces employing lambda expressions
+ System.out.println("\nApproach 6: Persons eligible for selective service " +
"(with Predicate parameter):");
printPersonsWithPredicate(
- rosterInstance,
+ students,
p -> p.getSex() == Student.Sex.MALE
&& p.getMark() >= 18
&& p.getMark() <= 25
);
- System.out.println();
-
- // Approach 7: Use Lamba Expressions Throughout Your Application
-
- System.out.println("Persons who are eligible for Selective Service " +
+ // Approach 7: Using lamba expressions throughout
+ System.out.println("\nApproach 7: Persons eligible for selective service " +
"(with Predicate and Consumer parameters):");
processPersons(
- rosterInstance,
+ students,
p -> p.getSex() == Student.Sex.MALE
&& p.getMark() >= 2
&& p.getMark() <= 3,
p -> p.print()
);
- System.out.println();
-
// Approach 7, second example
-
- System.out.println("Persons who are eligible for Selective Service " +
+ System.out.println("\nApproach 7, second example: Persons eligible for selective service " +
"(with Predicate, Function, and Consumer parameters):");
- processPersonsWithFunction(
- rosterInstance,
+ processPersonsByFunction(
+ students,
p -> p.getSex() == Student.Sex.MALE
&& p.getMark() >= 2
&& p.getMark() <= 3,
@@ -261,15 +232,12 @@ public class RosterTest {
email -> System.out.println(email)
);
- System.out.println();
-
- // Approach 8: Use Generics More Extensively
-
- System.out.println("Persons who are eligible for Selective Service " +
+ // Approach 8: Use generics more extensively
+ System.out.println("\nApproach 8: Persons eligible for selective service " +
"(generic version):");
processElements(
- rosterInstance,
+ students,
p -> p.getSex() == Student.Sex.MALE
&& p.getMark() >= 2
&& p.getMark() <= 3,
@@ -277,15 +245,13 @@ public class RosterTest {
email -> System.out.println(email)
);
- System.out.println();
-
- // Approach 9: Use Bulk Data Operations That Accept Lambda Expressions
+ // Approach 9: Using bulk data operations accepting lambda expressions
// as Parameters
- System.out.println("Persons who are eligible for Selective Service " +
+ System.out.println("\nApproach 9: Persons eligible for selective service " +
"(with bulk data operations):");
- rosterInstance
+ students
.stream()
.filter(
p -> p.getSex() == Student.Sex.MALE
@@ -294,4 +260,4 @@ public class RosterTest {
.map(p -> p.getEmailAddress())
.forEach(email -> System.out.println(email));
}
-}
+}
\ No newline at end of file
diff --git a/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/Student.java b/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/Student.java
index 80c48c353..6ed4bfd58 100644
--- a/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/Student.java
+++ b/P/Sda1/Streams/Template/src/main/java/de/hdm_stuttgart/mi/javastreams/Student.java
@@ -1,56 +1,13 @@
package de.hdm_stuttgart.mi.javastreams;
/*
- * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * - Neither the name of Oracle or the names of its
- * contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
- * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
- * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * Loosely derived from https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html.
*/
-import java.util.Arrays;
-import java.util.List;
/** Representing students among with examination marks. */
public class Student {
- /** @return Test sample of students. */
- public static List<Student> createRoster() { // Create test data records
-
- final Student[] roster = new Student[] {
- new Student("Fred", 2, Student.Sex.MALE, "fred@example.com")
- ,new Student("Jane", 1, Student.Sex.FEMALE, "jane@kiv.de")
- ,new Student("George", 4, Student.Sex.MALE, "george@math.edu")
- ,new Student("Bob", 2, Student.Sex.MALE, "bob@uk.edu")
- ,new Student("Kim", 2, Student.Sex.FEMALE, "wilde@serious.de")
- };
-
- return Arrays.asList(roster);
- }
-
/** Male or female */
public enum Sex {
/** */
@@ -60,12 +17,12 @@ public class Student {
final String extern;
- private Sex(final String extern) {this.extern = extern;}
+ Sex(final String extern) {this.extern = extern;}
@Override
public String toString(){return extern;}
}
- String name;
+ String name;
int mark;
Sex sex;
String emailAddress;
diff --git a/P/Sda1/Streams/Template/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java b/P/Sda1/Streams/Template/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java
index afbd1aced..61883b5a7 100644
--- a/P/Sda1/Streams/Template/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java
+++ b/P/Sda1/Streams/Template/src/test/java/de/hdm_stuttgart/mi/javastreams/Java8FunctionalTest.java
@@ -10,6 +10,7 @@ import java.util.stream.Collectors;
import org.hamcrest.Matchers;
import org.junit.Assert;
+import org.junit.FixMethodOrder;
import org.junit.Ignore;
import org.junit.Test;
@@ -17,18 +18,26 @@ import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import de.hdm_stuttgart.mi.javastreams.Student.Sex;
+import org.junit.runners.MethodSorters;
/**
* Testing functional queries.
*/
@Ignore // Remove me to enable testing
+@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class Java8FunctionalTest {
- final List<Student> roster = Student.createRoster();
+ static private final List<Student> students = ImmutableList.of(
+ new Student("Fred", 2, Student.Sex.MALE, "fred@example.com")
+ ,new Student("Jane", 1, Student.Sex.FEMALE, "jane@kiv.de")
+ ,new Student("George", 4, Student.Sex.MALE, "george@math.edu")
+ ,new Student("Bob", 2, Student.Sex.MALE, "bob@uk.edu")
+ ,new Student("Kim", 2, Student.Sex.FEMALE, "wilde@serious.de")
+ );
/**
* Order all male students by email and create a List<String> of their respective
- * names in that order eliminating possible duplicates:
+ * names alphabetically ordered eliminating possible duplicates:
*
* "Bob", 2, Student.Sex.MALE, "bob@uk.edu"
* "Fred", 2, Student.Sex.MALE, "fred@example.com"
@@ -42,7 +51,7 @@ public class Java8FunctionalTest {
public void allMaleDistinctNameOrderedByEmail() {
final List<String> emails =
- roster.
+ students.
stream().
filter(s -> s.sex == Sex.MALE).
map(Student::getName).
@@ -52,7 +61,7 @@ public class Java8FunctionalTest {
assertThat(
emails,
- Matchers.<List<String>> equalTo(
+ Matchers.equalTo(
ImmutableList.of("Bob", "Fred", "George")
)
);
@@ -66,13 +75,25 @@ public class Java8FunctionalTest {
*
* Expected value: 1 + 2 == 3
*
- * Implementation hint: Map objects to int and provide a suitable reduce operation.
- * You may want to read
- * https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html#reduce
+ * <p>Implementation hint: Process a stream of Student instances by:</p>
+ *
+ * <ol>
+ * <li>Filtering students having a german email.</li>
+ * <li>Map objects to int.</li>
+ * <li>Provide a suitable reduce operation.</li>
+ *
+ * </ol>
+ *
+ * <p>You may want to read
+ * <a href="https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html#reduce"
+ * >https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html#reduce</a>.</p>
*/
@Test
public void markSumAllStudentsMarksHavingEmail_Dot_de() {
- Assert.fail("Implement me!");// TODO
+ Assert.assertEquals(
+ 3, //Expected marks sum 3 == 1 + 2
+ 0 /* TODO: Start from stream students. ...*/
+ );
}
/**
--
GitLab