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lambda exercises #5

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ff4dbb7
lambda ex.1
nikitos19 Mar 31, 2017
7f16aa6
lambda exercise 2 Gladun Nikita
nikitos19 Apr 2, 2017
021a7a6
part2 arrowNotaion done and part3 Mapping done
nikitos19 Apr 4, 2017
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2 changes: 1 addition & 1 deletion build.gradle
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,6 @@ dependencies {
compileOnly 'org.projectlombok:lombok:+',
'edu.washington.cs.types.checker:checker-framework:+'

testCompile 'org.junit.jupiter:junit-jupiter-api:+',
testCompile 'org.junit.jupiter:junit-jupiter-api:5.0.0-M2',
'org.hamcrest:java-hamcrest:+'
}
5 changes: 3 additions & 2 deletions src/test/java/lambda/part1/example/Lambdas01.java
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Expand Up @@ -7,6 +7,7 @@
import com.google.common.collect.ImmutableList;
import data.Person;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;

import java.util.Arrays;
import java.util.Comparator;
Expand All @@ -19,8 +20,8 @@
// JSR-335 Lambda Expressions for the Java Programming Language

// https://github.com/Vyacheslav-Lapin/lambda

class Lambdas01 {
//@ExtendWith()
class Lambdas01{

@Test
void sortPersons() {
Expand Down
39 changes: 36 additions & 3 deletions src/test/java/lambda/part1/exercise/Lambdas01Exercise.java
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@@ -1,13 +1,21 @@
package lambda.part1.exercise;

import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import data.Person;
import org.junit.jupiter.api.Test;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.is;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.fail;

class Lambdas01Exercise {

Expand All @@ -19,7 +27,20 @@ void sortPersonsByAge() {
new Person("name 2", "lastName 1", 30)
};

// TODO use Arrays.sort
Arrays.sort(persons, new Comparator<Person>() {
@Override
public int compare(Person o1, Person o2) {
if(o1.getAge()>o2.getAge()){
return 1;
}
else if(o1.getAge() < o2.getAge()){
return -1;
}
else {
return 0;
}
}
});

assertArrayEquals(persons, new Person[]{
new Person("name 3", "lastName 3", 20),
Expand All @@ -38,8 +59,20 @@ void findFirstWithAge30() {

Person person = null;

// TODO use FluentIterable
final Optional<Person> optional = FluentIterable.from(persons)
.firstMatch(new Predicate<Person>() {
@Override
public boolean apply(Person p) {
return p.getAge() == 30;
}
});

assertEquals(person, new Person("name 1", "lastName 2", 30));
// assertEquals(person, new Person("name 1", "lastName 2", 30));
if(optional.isPresent()){
assertThat(optional.get(),is(new Person("name 1", "lastName 2", 30)));
}
else {
fail("");
}
}
}
15 changes: 12 additions & 3 deletions src/test/java/lambda/part1/exercise/Lambdas02Exercise.java
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@@ -1,9 +1,13 @@
package lambda.part1.exercise;

import com.google.common.base.Optional;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import data.Person;
import org.junit.jupiter.api.Test;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

import static org.junit.jupiter.api.Assertions.assertArrayEquals;
Expand All @@ -18,7 +22,7 @@ void sortPersonsByAge() {
new Person("name 2", "lastName 1", 30)
};

// TODO use Arrays.sort
Arrays.sort(persons, Comparator.comparing(p -> p.getAge()));

assertArrayEquals(persons, new Person[]{
new Person("name 3", "lastName 3", 20),
Expand All @@ -37,8 +41,13 @@ void findFirstWithAge30() {

Person person = null;

// TODO use FluentIterable
Optional<Person> optional = FluentIterable.from(persons)
.firstMatch(p -> p.getAge() == 30);

assertEquals(person, new Person("name 1", "lastName 2", 30));
if(optional.isPresent()){
optional.get().print();
}

assertEquals(optional.get(), new Person("name 1", "lastName 2", 30));
}
}
22 changes: 12 additions & 10 deletions src/test/java/lambda/part2/exercise/ArrowNotationExercise.java
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Expand Up @@ -4,6 +4,7 @@
import org.junit.jupiter.api.Test;

import java.util.function.BiFunction;
import java.util.function.BiPredicate;
import java.util.function.Function;

import static org.junit.jupiter.api.Assertions.assertEquals;
Expand All @@ -13,35 +14,36 @@ class ArrowNotationExercise {
@Test
void getAge() {
// Person -> Integer
final Function<Person, Integer> getAge = null; // TODO
final Function<Person, Integer> getAge = p -> p.getAge();

assertEquals(Integer.valueOf(33), getAge.apply(new Person("", "", 33)));
}

@Test
void compareAges() {
// TODO use BiPredicate
final BiPredicate<Person, Person> compareAges = (p1, p2) -> p1.getAge() == p2.getAge();
// compareAges: (Person, Person) -> boolean

throw new UnsupportedOperationException("Not implemented");
//assertEquals(true, compareAges.test(new Person("a", "b", 22), new Person("c", "d", 22)));
assertEquals(true, compareAges.test(new Person("a", "b", 22), new Person("c", "d", 22)));
}

// TODO
// getFullName: Person -> String
private static final Function<Person,String> getFullName = person ->
person.getFirstName() + " " + person.getLastName();

// TODO
// ageOfPersonWithTheLongestFullName: (Person -> String) -> (Person, Person) -> int
//
private BiFunction<Person, Person, Integer> ageOfPersonWithTheLongestFullName(Function<Person,String> f){
return (p1, p2) -> f.apply(p1).length() > f.apply(p2).length() ? p1.getAge() : p2.getAge();
}

@Test
void getAgeOfPersonWithTheLongestFullName() {
// Person -> String
final Function<Person, String> getFullName = null; // TODO
final Function<Person, String> getFullName = ArrowNotationExercise.getFullName;

// (Person, Person) -> Integer
// TODO use ageOfPersonWithTheLongestFullName(getFullName)
final BiFunction<Person, Person, Integer> ageOfPersonWithTheLongestFullName = null;
final BiFunction<Person, Person, Integer> ageOfPersonWithTheLongestFullName =
ageOfPersonWithTheLongestFullName(getFullName);

assertEquals(
Integer.valueOf(1),
Expand Down
55 changes: 35 additions & 20 deletions src/test/java/lambda/part3/exercise/Mapping.java
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Expand Up @@ -29,8 +29,12 @@ public List<T> getList() {
// [T] -> (T -> R) -> [R]
// [T1, T2, T3] -> (T -> R) -> [R1, R2, R3]
public <R> MapHelper<R> map(Function<T, R> f) {
// TODO
throw new UnsupportedOperationException();
final List<R> res = new ArrayList<>();
for (T t : list) {
res.add(f.apply(t));
}

return new MapHelper<R>(res);
}

// [T] -> (T -> [R]) -> [R]
Expand All @@ -47,6 +51,15 @@ public <R> MapHelper<R> flatMap(Function<T, List<R>> f) {
}
}

private List<JobHistoryEntry> ageOneYear(List<JobHistoryEntry> jobHistory) {
return new MapHelper<>(jobHistory).map(e -> e.withDuration(e.getDuration() + 1)).getList();
}

private List<JobHistoryEntry> replaceQa(List<JobHistoryEntry> jobHistory) {
return new MapHelper<>(jobHistory)
.map(e -> e.getPosition().equals("qa") ? e.withPosition("QA") : e).getList();
}

@Test
void mapping() {
final List<Employee> employees =
Expand All @@ -73,12 +86,10 @@ void mapping() {

final List<Employee> mappedEmployees =
new MapHelper<>(employees)
/*
.map(TODO) // change name to John .map(e -> e.withPerson(e.getPerson().withFirstName("John")))
.map(TODO) // add 1 year to experience duration .map(e -> e.withJobHistory(addOneYear(e.getJobHistory())))
.map(TODO) // replace qa with QA
* */
.getList();
.map(employee -> employee.withPerson(employee.getPerson().withFirstName("John")))
.map(employee -> employee.withJobHistory(ageOneYear(employee.getJobHistory())))
.map(employee -> employee.withJobHistory(replaceQa(employee.getJobHistory())))
.getList();

final List<Employee> expectedResult =
Arrays.asList(
Expand Down Expand Up @@ -108,21 +119,28 @@ void mapping() {

private static class LazyMapHelper<T, R> {

private final List<T> list;
private final Function<T, R> function;

LazyMapHelper(List<T> list, Function<T, R> function) {
this.list = list;
this.function = function;
}

static <T> LazyMapHelper<T, T> from(List<T> list) {
return new LazyMapHelper<>(list, Function.identity());
}

List<R> force() {
// TODO
throw new UnsupportedOperationException();
public List<R> force() {
final List<R> res = new ArrayList<>();
for(T t : list){
res.add(function.apply(t));
}
return res;
}

public <R2> LazyMapHelper<T, R2> map(Function<R, R2> f) {
// TODO
throw new UnsupportedOperationException();
return new LazyMapHelper<>(list,function.andThen(f));
}

}
Expand Down Expand Up @@ -163,7 +181,6 @@ <R2> LazyFlatMapHelper<T, R2> flatMap(Function<R, List<R2>> f) {
}



@Test
void lazy_mapping() {
final List<Employee> employees =
Expand All @@ -190,12 +207,10 @@ void lazy_mapping() {

final List<Employee> mappedEmployees =
LazyMapHelper.from(employees)
/*
.map(TODO) // change name to John
.map(TODO) // add 1 year to experience duration
.map(TODO) // replace qa with QA
* */
.force();
.map(e -> e.withPerson(e.getPerson().withFirstName("John")))
.map(e -> e.withJobHistory(ageOneYear(e.getJobHistory())))
.map(e -> e.withJobHistory(replaceQa(e.getJobHistory())))
.force();

final List<Employee> expectedResult =
Arrays.asList(
Expand Down