Merge pull request #8588 from sk1418/master

improvement of the article "How to Return Multiple Values From a Java…

core-java-modules/core-java-lang-2/pom.xml

@@ -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>

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsPair.java

@@ -0,0 +1,20 @@
+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();
+
+    }
+}

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsTriple.java

@@ -0,0 +1,23 @@
+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);
+    }
+}

core-java-modules/core-java-lang-2/src/test/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsPairUnitTest.java

@@ -0,0 +1,34 @@
+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());
+
+    }
+
+}

core-java-modules/core-java-lang-2/src/test/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsTripleUnitTest.java

@@ -0,0 +1,35 @@
+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();
+    }
+}