Bael 3510-method multiple return values (#8348)

* init

* first draft

* first review round changes

* second review round

* changing arg name

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

@@ -0,0 +1,49 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+public class Coordinates {
+
+    private double longitude;
+    private double latitude;
+    private String placeName;
+    
+    public Coordinates() {}
+    
+    public Coordinates(double longitude, double latitude, String placeName) {
+        this.longitude = longitude;
+        this.latitude = latitude;
+        this.placeName = placeName;
+    }
+
+    public double calculateDistance(Coordinates c) {
+        
+        double s1 = Math.abs(this.longitude - c.longitude);
+        double s2 = Math.abs(this.latitude - c.latitude);
+        
+        return Math.hypot(s1, s2);
+    }
+    
+    public double getLongitude() {
+        return longitude;
+    }
+
+    public void setLongitude(double longitude) {
+        this.longitude = longitude;
+    }
+
+    public double getLatitude() {
+        return latitude;
+    }
+
+    public void setLatitude(double latitude) {
+        this.latitude = latitude;
+    }
+
+    public String getPlaceName() {
+        return placeName;
+    }
+
+    public void setPlaceName(String placeName) {
+        this.placeName = placeName;
+    }
+    
+}

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

@@ -0,0 +1,27 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+class MultipleReturnValuesUsingArrays {
+
+    
+    static double[] getCoordinatesDoubleArray() {
+        
+        double[] coordinates = new double[2];
+
+        coordinates[0] = 10;
+        coordinates[1] = 12.5;
+        
+        return coordinates;
+    }
+
+    
+    static Number[] getCoordinatesNumberArray() {
+        
+        Number[] coordinates = new Number[2];
+
+        coordinates[0] = 10; //Integer
+        coordinates[1] = 12.5; //Double
+        
+        return coordinates;
+    }
+
+}

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

@@ -0,0 +1,30 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+class MultipleReturnValuesUsingCollections {
+
+    static List<Number> getCoordinatesList() {
+
+        List<Number> coordinates = new ArrayList<>();
+
+        coordinates.add(10);
+        coordinates.add(12.5);
+
+        return coordinates;
+    }
+
+    static Map<String, Number> getCoordinatesMap() {
+
+        Map<String, Number> coordinates = new HashMap<>();
+        
+        coordinates.put("longitude", 10);
+        coordinates.put("latitude", 12.5);
+
+        return coordinates;
+    }
+
+}

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

@@ -0,0 +1,14 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+class MultipleReturnValuesUsingContainer {
+
+    static Coordinates getCoordinates() {
+        
+        double longitude = 10;
+        double latitude = 12.5;
+        String placeName = "home";
+        
+        return new Coordinates(longitude, latitude, placeName);
+    }
+    
+}

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

@@ -0,0 +1,17 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import java.util.List;
+
+class MultipleReturnValuesUsingTuples {
+
+    static Tuple2<Coordinates, Double> getMostDistantPoint(List<Coordinates> coordinatesList,
+                                                           Coordinates target) {
+
+        return coordinatesList.stream()
+            .map(coor -> new Tuple2<>(coor, coor.calculateDistance(target)))
+            .max((d1, d2) -> Double.compare(d1.getSecond(), d2.getSecond()))
+            .get();
+
+    }
+
+}

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/methodmultiplereturnvalues/Tuple2.java

@@ -0,0 +1,31 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+public class Tuple2 <K, V> {
+
+    private K first;
+    private V second;
+    
+    public Tuple2() {}
+    
+    public Tuple2(K first, V second) {
+        this.first = first;
+        this.second = second;
+    }
+
+    public K getFirst() {
+        return first;
+    }
+    
+    public V getSecond() {
+        return second;
+    }
+
+    public void setFirst(K first) {
+        this.first = first;
+    }
+
+    public void setSecond(V second) {
+        this.second = second;
+    }
+
+}

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

@@ -0,0 +1,25 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+class MultipleReturnValuesUsingArraysUnitTest {
+
+    @Test
+    void whenUsingArrayOfDoubles_thenMultipleDoubleFieldsAreReturned() {
+
+        double[] coordinates = MultipleReturnValuesUsingArrays.getCoordinatesDoubleArray();
+        assertEquals(10, coordinates[0]);
+        assertEquals(12.5, coordinates[1]);
+    }
+
+    @Test
+    void whenUsingArrayOfNumbers_thenMultipleNumberFieldsAreReturned() {
+        
+        Number[] coordinates = MultipleReturnValuesUsingArrays.getCoordinatesNumberArray();
+        assertEquals(10, coordinates[0]);
+        assertEquals(12.5, coordinates[1]);
+
+    }
+    
+}

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

@@ -0,0 +1,25 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.util.List;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+
+class MultipleReturnValuesUsingCollectionsUnitTest {
+
+    @Test
+    void whenUsingList_thenMultipleFieldsAreReturned() {
+        
+        List<Number> coordinates = MultipleReturnValuesUsingCollections.getCoordinatesList();
+        assertEquals(Integer.valueOf(10), coordinates.get(0));
+        assertEquals(Double.valueOf(12.5), coordinates.get(1));
+    }
+    
+    @Test
+    void whenUsingMap_thenMultipleFieldsAreReturned() {
+        
+        Map<String, Number> coordinates = MultipleReturnValuesUsingCollections.getCoordinatesMap();
+        assertEquals(Integer.valueOf(10), coordinates.get("longitude"));
+        assertEquals(Double.valueOf(12.5), coordinates.get("latitude"));
+    }
+}

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

@@ -0,0 +1,17 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+class MultipleReturnValuesUsingContainerUnitTest {
+
+    @Test
+    void whenUsingContainerClass_thenMultipleFieldsAreReturned() {
+        
+        Coordinates coordinates = MultipleReturnValuesUsingContainer.getCoordinates();
+        
+        assertEquals(10, coordinates.getLongitude());
+        assertEquals(12.5, coordinates.getLatitude());
+        assertEquals("home", coordinates.getPlaceName());
+    }
+}

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

@@ -0,0 +1,31 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class MultipleReturnValuesUsingTuplesUnitTest {
+
+    @Test
+    void whenUsingTuple_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");
+        
+        Tuple2<Coordinates, Double> mostDistantPoint = MultipleReturnValuesUsingTuples.getMostDistantPoint(coordinatesList, target);
+        
+        assertEquals(1, mostDistantPoint.getFirst().getLongitude());
+        assertEquals(1, mostDistantPoint.getFirst().getLatitude());
+        assertEquals("home", mostDistantPoint.getFirst().getPlaceName());
+        assertEquals(5.66, BigDecimal.valueOf(mostDistantPoint.getSecond()).setScale(2, RoundingMode.HALF_UP).doubleValue());
+        
+    }
+    
+}