Merge pull request #8588 from sk1418/master

improvement of the article "How to Return Multiple Values From a Java…
This commit is contained in:
Eric Martin 2020-02-02 13:00:25 -06:00 committed by GitHub
commit fc4c5bab51
5 changed files with 117 additions and 0 deletions

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@ -15,6 +15,11 @@
</parent>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.9</version>
</dependency>
<dependency>
<groupId>commons-beanutils</groupId>
<artifactId>commons-beanutils</artifactId>

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package com.baeldung.methodmultiplereturnvalues;
import org.apache.commons.lang3.tuple.ImmutablePair;
import org.apache.commons.lang3.tuple.Pair;
import java.util.Comparator;
import java.util.List;
class MultipleReturnValuesUsingApacheCommonsPair {
static ImmutablePair<Coordinates, Double> getMostDistantPoint(
List<Coordinates> coordinatesList,
Coordinates target) {
return coordinatesList.stream()
.map(coordinates -> ImmutablePair.of(coordinates, coordinates.calculateDistance(target)))
.max(Comparator.comparingDouble(Pair::getRight))
.get();
}
}

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package com.baeldung.methodmultiplereturnvalues;
import org.apache.commons.lang3.tuple.ImmutableTriple;
import java.util.List;
import java.util.stream.Collectors;
class MultipleReturnValuesUsingApacheCommonsTriple {
static ImmutableTriple<Double, Double, Double> getMinAvgMaxTriple(
List<Coordinates> coordinatesList,
Coordinates target) {
List<Double> distanceList = coordinatesList.stream()
.map(coordinates -> coordinates.calculateDistance(target))
.collect(Collectors.toList());
Double minDistance = distanceList.stream().mapToDouble(Double::doubleValue).min().getAsDouble();
Double avgDistance = distanceList.stream().mapToDouble(Double::doubleValue).average().orElse(0.0D);
Double maxDistance = distanceList.stream().mapToDouble(Double::doubleValue).max().getAsDouble();
return ImmutableTriple.of(minDistance, avgDistance, maxDistance);
}
}

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package com.baeldung.methodmultiplereturnvalues;
import org.apache.commons.lang3.tuple.ImmutablePair;
import org.junit.jupiter.api.Test;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.List;
import static org.junit.jupiter.api.Assertions.assertEquals;
class MultipleReturnValuesUsingApacheCommonsPairUnitTest {
@Test
void whenUsingPair_thenMultipleFieldsAreReturned() {
List<Coordinates> coordinatesList = new ArrayList<>();
coordinatesList.add(new Coordinates(1, 1, "home"));
coordinatesList.add(new Coordinates(2, 2, "school"));
coordinatesList.add(new Coordinates(3, 3, "hotel"));
Coordinates target = new Coordinates(5, 5, "gym");
ImmutablePair<Coordinates, Double> mostDistantPoint = MultipleReturnValuesUsingApacheCommonsPair.getMostDistantPoint(coordinatesList, target);
assertEquals(1, mostDistantPoint.getLeft().getLongitude());
assertEquals(1, mostDistantPoint.getLeft().getLatitude());
assertEquals("home", mostDistantPoint.getLeft().getPlaceName());
assertEquals(5.66, BigDecimal.valueOf(mostDistantPoint.getRight()).setScale(2, RoundingMode.HALF_UP).doubleValue());
}
}

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package com.baeldung.methodmultiplereturnvalues;
import org.apache.commons.lang3.tuple.ImmutableTriple;
import org.junit.jupiter.api.Test;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.List;
import static org.junit.jupiter.api.Assertions.assertEquals;
class MultipleReturnValuesUsingApacheCommonsTripleUnitTest {
@Test
void whenUsingTriple_thenMultipleFieldsAreReturned() {
List<Coordinates> coordinatesList = new ArrayList<>();
coordinatesList.add(new Coordinates(1, 1, "home"));
coordinatesList.add(new Coordinates(2, 2, "school"));
coordinatesList.add(new Coordinates(3, 3, "hotel"));
Coordinates target = new Coordinates(5, 5, "gym");
ImmutableTriple<Double, Double, Double> minAvgMax = MultipleReturnValuesUsingApacheCommonsTriple.getMinAvgMaxTriple(coordinatesList, target);
assertEquals(2.83, scaleDouble(minAvgMax.left)); //min
assertEquals(4.24, scaleDouble(minAvgMax.middle)); //avg
assertEquals(5.66, scaleDouble(minAvgMax.right)); //max
}
private double scaleDouble(Double d) {
return BigDecimal.valueOf(d).setScale(2, RoundingMode.HALF_UP).doubleValue();
}
}