add Command pattern v1 implementation

Author: BuntyRaghani

README.md

@@ -10,4 +10,5 @@ Behavioural patterns are all about the interaction or communication between the
 | State Pattern | state-pattern |
 | Iterator Pattern | iterator-pattern |
 | Strategy Pattern | strategy-pattern |
-| Template Method Pattern | template-method-pattern |
+| Template Method Pattern | template-method-pattern |
+| Command Pattern | command-pattern |

command-pattern/README.md

@@ -0,0 +1,3 @@
+# Command Design Pattern
+
+**Command pattern is used to implement loose coupling in a request-response model. It is used to decouple the sender from the receiver.**

command-pattern/pom.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>java-behavioral-design-patterns</artifactId>
+        <groupId>com.example</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>command-pattern</artifactId>
+
+    <properties>
+        <maven.compiler.source>16</maven.compiler.source>
+        <maven.compiler.target>16</maven.compiler.target>
+    </properties>
+
+</project>

command-pattern/src/main/java/com/example/command/v1/AddCustomerConcreteCommand.java

@@ -0,0 +1,18 @@
+package com.example.command.v1;
+
+import com.example.command.v1.framework.Command;
+
+public class AddCustomerConcreteCommand implements Command {
+
+    private CustomerServiceReceiver customerServiceReceiver;
+
+    public AddCustomerConcreteCommand(CustomerServiceReceiver customerServiceReceiver) {
+        this.customerServiceReceiver = customerServiceReceiver;
+    }
+
+    @Override
+    public void execute() {
+        // delegating the work to add customer method of customer service receiver
+        customerServiceReceiver.addCustomer();
+    }
+}

command-pattern/src/main/java/com/example/command/v1/Application.java

@@ -0,0 +1,16 @@
+package com.example.command.v1;
+
+import com.example.command.v1.framework.ButtonInvoker;
+import com.example.command.v1.framework.Command;
+
+public class Application {
+
+    public static void main(String[] args) {
+
+        CustomerServiceReceiver customerServiceReceiver = new CustomerServiceReceiver();
+        Command addCustomerConcreteCommand = new AddCustomerConcreteCommand(customerServiceReceiver);
+        ButtonInvoker buttonInvoker = new ButtonInvoker(addCustomerConcreteCommand);
+
+        buttonInvoker.click();
+    }
+}

command-pattern/src/main/java/com/example/command/v1/CustomerServiceReceiver.java

@@ -0,0 +1,8 @@
+package com.example.command.v1;
+
+public class CustomerServiceReceiver {
+
+    public void addCustomer() {
+        System.out.println("Add customer");
+    }
+}

command-pattern/src/main/java/com/example/command/v1/framework/ButtonInvoker.java

@@ -0,0 +1,24 @@
+package com.example.command.v1.framework;
+
+public class ButtonInvoker {
+
+    private String label;
+    private Command command;
+
+    public ButtonInvoker(Command command) {
+        this.command = command;
+    }
+
+    public void click() {
+        // delegating the work to command object
+        command.execute();
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public void setLabel(String label) {
+        this.label = label;
+    }
+}

command-pattern/src/main/java/com/example/command/v1/framework/Command.java

@@ -0,0 +1,6 @@
+package com.example.command.v1.framework;
+
+public interface Command {
+
+    void execute();
+}

pom.xml

@@ -15,6 +15,7 @@
         <module>iterator-pattern</module>
         <module>strategy-pattern</module>
         <module>template-method-pattern</module>
+        <module>command-pattern</module>
     </modules>
 
     <properties>