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Done with zipMap (Mikhail Figurin) #27

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Done with zipMap (Mikhail Figurin) #27

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107 changes: 107 additions & 0 deletions src/test/java/option/OptionalExample.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,42 @@

import java.util.Optional;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;

import static org.junit.Assert.assertEquals;

public class OptionalExample {

public static <T1, T2, R> Optional<R> zipMap1(Optional<T1> o1, Optional<T2> o2, BiFunction<T1, T2, R> f) {
if (o1.isPresent() && o2.isPresent()) {
return Optional.ofNullable(f.apply(o1.get(), o2.get()));
} else {
return Optional.empty();
}
}

public static <T1, T2, R> Optional<R> zipMap2(Optional<T1> o1, Optional<T2> o2, BiFunction<T1, T2, R> f) {
return o1.flatMap(
t1 -> o2.flatMap(
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@senia-psm senia-psm Jun 23, 2017 •
edited
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You can use map here. optional.map(f) returns empty option in case of null result of f.

t2 -> Optional.ofNullable(f.apply(t1, t2))));
}

@Test
public void zipTest() {
Optional<String> o1 = Optional.of("hello");
Optional<Integer> o2 = Optional.of(404);

BiFunction<String, Integer, String> f = (s, i) -> "" + s + i;
Optional<String> rOption1 = zipMap1(o1, o2, f);
Optional<String> rOption2 = zipMap2(o1, o2, f);

assertEquals(rOption1.get(), "hello404");
assertEquals(rOption2.get(), "hello404");
}

@Test
public void get() {
final Optional<String> o1 = Optional.empty();
Expand Down Expand Up @@ -50,6 +80,83 @@ public void map() {
assertEquals(expected, actual);
}

@Test
public void filter() {
Optional<String> o = getOptional();
Predicate<String> p = String::isEmpty;
Optional<String> expected = o.filter(p);

Optional<String> actual = (o.isPresent() && p.test(o.get()))
? o : Optional.empty();

assertEquals(expected, actual);
}

@Test
public void flatMap() {
Optional<String> o = getOptional();
Function<String, Optional<String>> f = (s) -> Optional.of(s + "hello");
Optional<String> expected = o.flatMap(f);

Optional<String> actual = (o.isPresent())
? f.apply(o.get()) : Optional.empty();

assertEquals(expected, actual);
}

@Test
public void orElse() {
Optional<String> o = getOptional();
String str = "hello";
String expected = o.orElse(str);

String actual = (o.isPresent())
? o.get() : str;

assertEquals(expected, actual);
}

@Test
public void orElseGet() {
Optional<String> o = getOptional();
Supplier<String> s = () -> "hello";
String expected = o.orElseGet(s);

String actual = (o.isPresent())
? o.get() : s.get();

assertEquals(expected, actual);
}

@Test
public void orElseThrow() {
Optional<String> o = getOptional();
Supplier<RuntimeException> s = RuntimeException::new;

String expected = null;
Exception e1 = new Exception();

try {
expected = o.orElseThrow(s);
} catch (RuntimeException e) {
e1 = e;
}

String actual = null;
try {
if (o.isPresent()) {
actual = o.get();
} else {
throw s.get();
}
} catch (RuntimeException e) {
assertEquals(e1.getClass(), e.getClass());
}

assertEquals(expected, actual);

}

private Optional<String> getOptional() {
return ThreadLocalRandom.current().nextBoolean()
? Optional.empty()
Expand Down