Implements visitor

Author: LBeghini

README.md

@@ -1,92 +1,9 @@
 # ☕ Java Design Patterns
 
-## About
+## Visitor
 
-This application is a simple Java Console Application that aims to implement design pattern examples to a Programmin Language Class. A set of design patterns will be developed
-each week, and they are divided in different [branches](https://github.com/LBeghini/Java-Design-Patterns/branches).  
+Visitor pattern is a way to perform operations of a determinated structure build outside the structure. 
 
-The main branch is just a template for every other branch.
+For example, let's say we have a Museum, and we want to see the masterpieces. However, the arts don't come with an exhibit method, and you don't have the rights to change anything inside the classes.
 
-Also, to make it easier to download the source code, [releases](https://github.com/LBeghini/Java-Design-Patterns/releases) are created related to the task of the week, giving a snapshot of the code for that specific implementation.
-
-## Implemented design patterns
-
-### Behavioural patterns
-
-- [x] [Chain of responsibility](https://github.com/LBeghini/Java-Design-Patterns/tree/4-chain-of-responsibility)
-- [x] [Command](https://github.com/LBeghini/Java-Design-Patterns/tree/6-command)
-- [x] [Interpreter](https://github.com/LBeghini/Java-Design-Patterns/tree/9-interpreter)
-- [x] [Iterator](https://github.com/LBeghini/Java-Design-Patterns/tree/4-iterator)
-- [x] [Mediator](https://github.com/LBeghini/Java-Design-Patterns/tree/9-mediator)
-- [x] [Memento](https://github.com/LBeghini/Java-Design-Patterns/tree/5-memento)
-- [x] [Observer](https://github.com/LBeghini/Java-Design-Patterns/tree/5-observer)
-- [x] [State](https://github.com/LBeghini/Java-Design-Patterns/tree/3-state)
-- [x] [Strategy](https://github.com/LBeghini/Java-Design-Patterns/tree/6-strategy)
-- [x] [Template method](https://github.com/LBeghini/Java-Design-Patterns/tree/4-template-method)
-
-### Creational patterns
-
-- [ ] Abstract factory
-- [x] [Builder](https://github.com/LBeghini/Java-Design-Patterns/tree/1-builder)
-- [x] [Factory method](https://github.com/LBeghini/Java-Design-Patterns/tree/2-factory-method)
-- [x] [Prototype](https://github.com/LBeghini/Java-Design-Patterns/tree/2-prototype)
-- [x] [Singleton](https://github.com/LBeghini/Java-Design-Patterns/tree/1-singleton)
-
-### Structural patterns
-
-- [x] [Adapter](https://github.com/LBeghini/Java-Design-Patterns/tree/7-adapter)
-- [x] [Bridge](https://github.com/LBeghini/Java-Design-Patterns/tree/7-bridge)
-- [x] [Composite](https://github.com/LBeghini/Java-Design-Patterns/tree/8-composite)
-- [ ] Decorator
-- [x] [Facade](https://github.com/LBeghini/Java-Design-Patterns/tree/8-facade)
-- [x] [Flyweight](https://github.com/LBeghini/Java-Design-Patterns/tree/10-flyweight)
-- [x] [Proxy](https://github.com/LBeghini/Java-Design-Patterns/tree/10-proxy)
-
-
-## Technologies
-
-- Java
-- JUnit
-- Maven
-
-## Requirements 
-
-To run and edit the project, be sure to have installed in your computer the following softwares:
-- A code editor
-
-After that, you'll need to clone this repo:
-
-```bash
-git clone https://github.com/LBeghini/Java-Design-Patterns.git
-```
-
-## Change branch
-
-To change to a different branch, run the command:
-
-```bash
-git checkout name-of-the-branch
-```
-
-The branch names have the pattern:
-
-```bash
-{number-of-the-week}-{pattern-name}
-```
-
-> `number-of-the-week` corresponds to the week asked to be implemented certain pattern 
-
-## Testing
-
-This project has no aim to run any of the implemented classes, as the goal is the code itself. However, the classes will be tested to visualize the behaviour and implementation 
-of the patterns.  
-
-You can run the tests using the maven wrapper:
-
-```bash
-./mvnw test 
-```
-
-## :balance_scale: License
-
-[MIT License](https://github.com/LBeghini/Java-Design-Patterns/blob/main/LICENSE)
+So you use the Museum as a Visitor to get the exhibitions of the masterpieces.

pom.xml

@@ -31,6 +31,11 @@
       <version>5.7.1</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.code.gson</groupId>
+      <artifactId>gson</artifactId>
+      <version>2.8.5</version>
+    </dependency>
   </dependencies>
 
   <build>

src/main/java/com/language/programming/model/Art.java

@@ -0,0 +1,7 @@
+package com.language.programming.model;
+
+public interface Art {
+
+    String accept(Visitor visitor);
+    
+}

src/main/java/com/language/programming/model/Museum.java

@@ -0,0 +1,35 @@
+package com.language.programming.model;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.language.programming.model.visitors.Painting;
+import com.language.programming.model.visitors.Sculpture;
+
+public class Museum implements Visitor {
+
+    private static Museum instance = new Museum();
+    
+    private Museum() {};
+    
+    public static Museum getInstance() {
+        return instance;
+    }
+
+    public String exhibit(Art art) {
+        return art.accept(this);
+    }
+
+    @Override
+    public String exhibit(Painting painting) {
+        Gson gson = new GsonBuilder().setPrettyPrinting().create();
+        return gson.toJson(painting);
+    }
+
+    @Override
+    public String exhibit(Sculpture sculpture) {
+        Gson gson = new GsonBuilder().setPrettyPrinting().create();
+        return gson.toJson(sculpture);
+    }
+    
+    
+}

src/main/java/com/language/programming/model/Visitor.java

@@ -0,0 +1,11 @@
+package com.language.programming.model;
+
+import com.language.programming.model.visitors.Painting;
+import com.language.programming.model.visitors.Sculpture;
+
+public interface Visitor {
+
+    String exhibit(Painting painting);
+    String exhibit(Sculpture sculpture);
+    
+}

src/main/java/com/language/programming/model/visitors/Painting.java

@@ -0,0 +1,37 @@
+package com.language.programming.model.visitors;
+
+import com.language.programming.model.Art;
+import com.language.programming.model.Visitor;
+
+public class Painting implements Art {
+
+    private String name;
+    private String artist;
+
+    public Painting(String name, String artist) {
+        this.name = name;
+        this.artist = artist;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getArtist() {
+        return artist;
+    }
+
+    public void setArtist(String artist) {
+        this.artist = artist;
+    }
+
+    @Override
+    public String accept(Visitor visitor) {
+        return visitor.exhibit(this);
+    }
+    
+}

src/main/java/com/language/programming/model/visitors/Sculpture.java

@@ -0,0 +1,37 @@
+package com.language.programming.model.visitors;
+
+import com.language.programming.model.Art;
+import com.language.programming.model.Visitor;
+
+public class Sculpture implements Art{
+
+    private String name;
+    private String artist;
+
+    public Sculpture(String name, String artist) {
+        this.name = name;
+        this.artist = artist;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getArtist() {
+        return artist;
+    }
+
+    public void setArtist(String artist) {
+        this.artist = artist;
+    }
+
+    @Override
+    public String accept(Visitor visitor) {
+        return visitor.exhibit(this);
+    }
+    
+}

src/test/java/com/language/programming/model/MuseumTest.java

@@ -0,0 +1,23 @@
+package com.language.programming.model;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.language.programming.model.visitors.*;
+
+public class MuseumTest {
+        
+    @Test
+    public void shouldExhibitPainting() {
+        Painting painting = new Painting("Mona Lisa", "Leonardo da Vinci"); 
+        assertEquals("{\n  \"name\": \"Mona Lisa\",\n  \"artist\": \"Leonardo da Vinci\"\n}", Museum.getInstance().exhibit(painting));
+    }
+
+    @Test
+    public void shouldExhibitSculpture() {
+        Sculpture sculpture = new Sculpture("The Thinker", "Auguste Rodin"); 
+        assertEquals("{\n  \"name\": \"The Thinker\",\n  \"artist\": \"Auguste Rodin\"\n}", Museum.getInstance().exhibit(sculpture));
+    }
+    
+}