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

protobuffer/README.md

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+## Google Protocol Buffer
+
+This module contains articles about Google Protocol Buffer.
+
+### Relevant articles
+
+- [Introduction to Google Protocol Buffer](https://www.baeldung.com/google-protocol-buffer)

protobuffer/pom.xml

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+<?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">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>protobuffer</artifactId>
+	<name>protobuffer</name>
+	
+    <parent>
+        <artifactId>parent-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java</artifactId>
+            <version>${protobuf.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <protobuf.version>3.2.0</protobuf.version>
+    </properties>
+
+</project>

protobuffer/src/main/resources/addressbook.proto

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+package protobuf;
+
+option java_package = "com.baeldung.protobuf";
+option java_outer_classname = "AddressBookProtos";
+
+message Person {
+  required string name = 1;
+  required int32 id = 2;
+  optional string email = 3;
+
+  repeated string numbers = 4;
+}
+
+message AddressBook {
+  repeated Person people = 1;
+}

protobuffer/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

protobuffer/src/test/java/com/baeldung/protobuf/ProtobufUnitTest.java

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+package com.baeldung.protobuf;
+
+
+import org.junit.After;
+import org.junit.Test;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.Random;
+
+import static org.junit.Assert.assertEquals;
+
+public class ProtobufUnitTest {
+    private final String filePath = "address_book";
+
+    @After
+    public void cleanup() throws IOException {
+        Files.deleteIfExists(Paths.get(filePath));
+    }
+
+    @Test
+    public void givenGeneratedProtobufClass_whenCreateClass_thenShouldCreateJavaInstance() {
+        //when
+        String email = "j@baeldung.com";
+        int id = new Random().nextInt();
+        String name = "Michael Program";
+        String number = "01234567890";
+        AddressBookProtos.Person person =
+                AddressBookProtos.Person.newBuilder()
+                        .setId(id)
+                        .setName(name)
+                        .setEmail(email)
+                        .addNumbers(number)
+                        .build();
+        //then
+        assertEquals(person.getEmail(), email);
+        assertEquals(person.getId(), id);
+        assertEquals(person.getName(), name);
+        assertEquals(person.getNumbers(0), number);
+    }
+
+
+    @Test
+    public void givenAddressBookWithOnePerson_whenSaveAsAFile_shouldLoadFromFileToJavaClass() throws IOException {
+        //given
+        String email = "j@baeldung.com";
+        int id = new Random().nextInt();
+        String name = "Michael Program";
+        String number = "01234567890";
+        AddressBookProtos.Person person =
+                AddressBookProtos.Person.newBuilder()
+                        .setId(id)
+                        .setName(name)
+                        .setEmail(email)
+                        .addNumbers(number)
+                        .build();
+
+        //when
+        AddressBookProtos.AddressBook addressBook = AddressBookProtos.AddressBook.newBuilder().addPeople(person).build();
+        FileOutputStream fos = new FileOutputStream(filePath);
+        addressBook.writeTo(fos);
+        fos.close();
+
+        //then
+        FileInputStream fis = new FileInputStream(filePath);
+        AddressBookProtos.AddressBook deserialized =
+                AddressBookProtos.AddressBook.newBuilder().mergeFrom(fis).build();
+        fis.close();
+        assertEquals(deserialized.getPeople(0).getEmail(), email);
+        assertEquals(deserialized.getPeople(0).getId(), id);
+        assertEquals(deserialized.getPeople(0).getName(), name);
+        assertEquals(deserialized.getPeople(0).getNumbers(0), number);
+
+
+    }
+}