Implements command

Author: LBeghini

README.md

@@ -1,90 +1,10 @@
 # ☕ Java Design Patterns
 
-## About
+## Command
 
-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).  
+Command pattern stores requests as command objects that perform actions or undo it at a later time.
 
-The main branch is just a template for every other branch.
+An artist is a person that makes lots of mistakes before succeed on his artwork. It's useful for him to be able to keep track of his improvements and undo it if necessary.
 
-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.
+For example, if the artist is writing a book, he needs to be able to write, and undo it's last writing until he finds the best phrase to continue the history. So it can perform an action of write and cancel.
 
-## Implemented design patterns
-
-### Behavioural patterns
-
-- [x] [Chain of responsibility](https://github.com/LBeghini/Java-Design-Patterns/tree/4-chain-of-responsibility)
-- [ ] Command
-- [x] [Iterator](https://github.com/LBeghini/Java-Design-Patterns/tree/4-iterator)
-- [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)
-- [ ] 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
-
-- [ ] Adapter
-- [ ] Bridge
-- [ ] Composite
-- [ ] Decorator
-- [ ] Facade
-- [ ] Flyweight
-- [ ] Mediator
-- [ ] 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)

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

@@ -0,0 +1,9 @@
+package com.language.programming.model;
+
+public interface Action {
+
+    void execute();
+
+    void cancel();
+
+}

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

@@ -0,0 +1,19 @@
+package com.language.programming.model;
+
+import java.util.Stack;
+
+public class Artist {
+
+    private Stack<Action> actions = new Stack<>();
+
+    public void executeAction(Action action) {
+        this.actions.add(action);
+        action.execute();
+    }
+
+    public void cancelLastAction() {
+        Action lastAction = actions.pop();
+        lastAction.cancel();
+    }
+
+}

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

@@ -0,0 +1,25 @@
+package com.language.programming.model;
+
+import com.language.programming.model.enumerations.Condition;
+
+public class Book {
+
+    private Condition condition;
+
+    public Book() {
+        this.condition = Condition.EMPTY;
+    }
+
+    public String getCondition() {
+        return this.condition.toString();
+    }
+
+    public void write() {
+        this.condition = Condition.PROGRESS;
+    }
+
+    public void erase() {
+        this.condition = Condition.REGRESS;
+    }
+
+}

src/main/java/com/language/programming/model/actions/Erase.java

@@ -0,0 +1,24 @@
+package com.language.programming.model.actions;
+
+import com.language.programming.model.Book;
+import com.language.programming.model.Action;
+
+public class Erase implements Action {
+
+    private Book book;
+
+    public Erase(Book book) {
+        this.book = book;
+    }
+
+    @Override
+    public void execute() {
+        this.book.erase();
+    }
+
+    @Override
+    public void cancel() {
+        this.book.write();
+    }
+
+}

src/main/java/com/language/programming/model/actions/Write.java

@@ -0,0 +1,24 @@
+package com.language.programming.model.actions;
+
+import com.language.programming.model.Book;
+import com.language.programming.model.Action;
+
+public class Write implements Action {
+
+    private Book book;
+
+    public Write(Book book) {
+        this.book = book;
+    }
+
+    @Override
+    public void execute() {
+        this.book.write();
+    }
+
+    @Override
+    public void cancel() {
+        this.book.erase();
+    }
+
+}

src/main/java/com/language/programming/model/enumerations/Condition.java

@@ -0,0 +1,19 @@
+package com.language.programming.model.enumerations;
+
+public enum Condition {
+    PROGRESS("Writing..."), REGRESS("Erasing..."), EMPTY("Not yet written.");
+
+    private final String description;
+
+    private Condition(String description) {
+        this.description = description;
+    }
+
+    public boolean equalsName(String name) {
+        return description.equals(name);
+    }
+
+    public String toString() {
+        return this.description;
+    }
+}

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

@@ -0,0 +1,52 @@
+package com.language.programming.model;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.language.programming.model.actions.Erase;
+import com.language.programming.model.actions.Write;
+
+import org.junit.jupiter.api.BeforeEach;
+
+public class PoetTest {
+
+    Book book;
+    Artist artist;
+
+    @BeforeEach
+    void setUp() {
+        book = new Book();
+        artist = new Artist();
+
+    }
+
+    @Test
+    public void shouldWriteBook() {
+        Action write = new Write(book);
+        artist.executeAction(write);
+
+        assertEquals("Writing...", book.getCondition());
+    }
+
+    @Test
+    public void shouldEraseBook() {
+        Action erase = new Erase(book);
+        artist.executeAction(erase);
+
+        assertEquals("Erasing...", book.getCondition());
+    }
+
+    @Test
+    public void shouldCancelEraseBook() {
+        Action write = new Write(book);
+        Action erase = new Erase(book);
+
+        artist.executeAction(write);
+        artist.executeAction(erase);
+        artist.cancelLastAction();
+
+        assertEquals("Writing...", book.getCondition());
+    }
+
+}