Merge pull request #8105 from vimde/master

BAEL-3091: The Prototype Pattern in Java (changed code based on valid comments from a reader)

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

@@ -0,0 +1,23 @@
+package com.baeldung.prototype;
+
+public class PineTree extends Tree {
+
+    private String type;
+
+    public PineTree(double mass, double height) {
+        super(mass, height);
+        this.type = "Pine";
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    @Override
+    public Tree copy() {
+        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

@@ -0,0 +1,23 @@
+package com.baeldung.prototype;
+
+public class PlasticTree extends Tree {
+
+    private String name;
+
+    public PlasticTree(double mass, double height) {
+        super(mass, height);
+        this.name = "PlasticTree";
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public Tree copy() {
+        PlasticTree plasticTreeClone = new PlasticTree(this.getMass(), this.getHeight());
+        plasticTreeClone.setPosition(this.getPosition());
+        return plasticTreeClone;
+    }
+
+}

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

@@ -1,6 +1,6 @@
 package com.baeldung.prototype;
 
-public class Tree implements Cloneable {
+public abstract class Tree {
 
     private double mass;
     private double height;
@@ -35,20 +35,10 @@ public class Tree implements Cloneable {
         return position;
     }
 
-    @Override
-    public Tree clone() {
-        Tree tree = null;
-        try {
-            tree = (Tree) super.clone();
-        } catch (CloneNotSupportedException e) {
-            e.printStackTrace();
-        }
-        return tree;
-    }
-
     @Override
     public String toString() {
         return "Tree [mass=" + mass + ", height=" + height + ", position=" + position + "]";
     }
 
+    public abstract Tree copy();
 }

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

@@ -2,23 +2,67 @@ 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 {
 
     @Test
-    public void givenATreePrototypeWhenClonedThenCreateA_Clone() {
+    public void givenAPlasticTreePrototypeWhenClonedThenCreateA_Clone() {
         double mass = 10.0;
         double height = 3.7;
         Position position = new Position(3, 7);
         Position otherPosition = new Position(4, 8);
 
-        Tree tree = new Tree(mass, height);
+        PlasticTree plasticTree = new PlasticTree(mass, height);
-        tree.setPosition(position);
+        plasticTree.setPosition(position);
-        Tree anotherTree = tree.clone();
+        PlasticTree anotherPlasticTree = (PlasticTree) plasticTree.copy();
-        anotherTree.setPosition(otherPosition);
+        anotherPlasticTree.setPosition(otherPosition);
 
-        assertEquals(position, tree.getPosition());
+        assertEquals(position, plasticTree.getPosition());
-        assertEquals(otherPosition, anotherTree.getPosition());
+        assertEquals(otherPosition, anotherPlasticTree.getPosition());
+
+    }
+
+    @Test
+    public void givenAPineTreePrototypeWhenClonedThenCreateA_Clone() {
+        double mass = 10.0;
+        double height = 3.7;
+        Position position = new Position(3, 7);
+        Position otherPosition = new Position(4, 8);
+
+        PineTree pineTree = new PineTree(mass, height);
+        pineTree.setPosition(position);
+        PineTree anotherPineTree = (PineTree) pineTree.copy();
+        anotherPineTree.setPosition(otherPosition);
+
+        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());
     }
 }