BAEL-3091: The Prototype Pattern in Java (further changes based on suggestions)

patterns/design-patterns-creational/src/main/java/com/baeldung/prototype/PineTree.java

@@ -15,7 +15,9 @@ public class PineTree extends Tree {
 
     @Override
     public Tree copy() {
-        return new PineTree(this.getMass(), this.getHeight());
+        PineTree pineTreeClone = new PineTree(this.getMass(), this.getHeight());
+        pineTreeClone.setPosition(this.getPosition());
+        return pineTreeClone;
     }
 
 }

patterns/design-patterns-creational/src/main/java/com/baeldung/prototype/PlasticTree.java

@@ -8,14 +8,16 @@ public class PlasticTree extends Tree {
         super(mass, height);
         this.name = "PlasticTree";
     }
-    
+
     public String getName() {
         return name;
     }
 
     @Override
     public Tree copy() {
-        return new PlasticTree(this.getMass(), this.getHeight());
+        PlasticTree plasticTreeClone = new PlasticTree(this.getMass(), this.getHeight());
+        plasticTreeClone.setPosition(this.getPosition());
+        return plasticTreeClone;
     }
 
 }

patterns/design-patterns-creational/src/test/java/com/baeldung/prototype/TreePrototypeUnitTest.java

@@ -2,6 +2,10 @@ package com.baeldung.prototype;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import java.util.Arrays;
+import java.util.List;
+import static java.util.stream.Collectors.toList;
+
 import org.junit.jupiter.api.Test;
 
 public class TreePrototypeUnitTest {
@@ -38,4 +42,27 @@ public class TreePrototypeUnitTest {
         assertEquals(position, pineTree.getPosition());
         assertEquals(otherPosition, anotherPineTree.getPosition());
     }
+    
+    @Test
+    public void givenA_ListOfTreesWhenClonedThenCreateListOfClones() {
+        double mass = 10.0;
+        double height = 3.7;
+        Position position = new Position(3, 7);
+        Position otherPosition = new Position(4, 8);
+        
+        PlasticTree plasticTree = new PlasticTree(mass, height);
+        plasticTree.setPosition(position);
+        PineTree pineTree = new PineTree(mass, height);
+        pineTree.setPosition(otherPosition);
+        
+        List<Tree> trees = Arrays.asList(plasticTree, pineTree);
+        
+        List<Tree> treeClones = trees.stream().map(Tree::copy).collect(toList());
+        
+        Tree plasticTreeClone = treeClones.get(0);
+        
+        assertEquals(mass, plasticTreeClone.getMass());
+        assertEquals(height, plasticTreeClone.getHeight());
+        assertEquals(position, plasticTreeClone.getPosition());
+    }
 }