Merge branch 'master' into bael-1908

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "testgitrepo"]
-	path = testgitrepo
-	url = /home/prd/Development/projects/idea/tutorials/spring-boot/src/main/resources/testgitrepo/

algorithms/README.md

@@ -22,3 +22,6 @@
 - [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)
 - [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)
 - [Find All Pairs of Numbers in an Array That Add Up to a Given Sum](http://www.baeldung.com/java-algorithm-number-pairs-sum)
+- [Converting Between Roman and Arabic Numerals in Java](http://www.baeldung.com/java-convert-roman-arabic)
+- [Practical Java Examples of the Big O Notation](http://www.baeldung.com/java-algorithm-complexity)
+- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)

algorithms/src/main/java/com/baeldung/algorithms/mcts/montecarlo/MonteCarloTreeSearch.java

@@ -10,7 +10,7 @@ public class MonteCarloTreeSearch {
 
     private static final int WIN_SCORE = 10;
     private int level;
-    private int oponent;
+    private int opponent;
 
     public MonteCarloTreeSearch() {
         this.level = 3;
@@ -32,11 +32,11 @@ public class MonteCarloTreeSearch {
         long start = System.currentTimeMillis();
         long end = start + 60 * getMillisForCurrentLevel();
 
-        oponent = 3 - playerNo;
+        opponent = 3 - playerNo;
         Tree tree = new Tree();
         Node rootNode = tree.getRoot();
         rootNode.getState().setBoard(board);
-        rootNode.getState().setPlayerNo(oponent);
+        rootNode.getState().setPlayerNo(opponent);
 
         while (System.currentTimeMillis() < end) {
             // Phase 1 - Selection
@@ -93,7 +93,7 @@ public class MonteCarloTreeSearch {
         State tempState = tempNode.getState();
         int boardStatus = tempState.getBoard().checkStatus();
 
-        if (boardStatus == oponent) {
+        if (boardStatus == opponent) {
             tempNode.getParent().getState().setWinScore(Integer.MIN_VALUE);
             return boardStatus;
         }

algorithms/src/main/java/com/baeldung/algorithms/romannumerals/RomanArabicConverter.java

@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.romannumerals;
+
+import java.util.List;
+
+class RomanArabicConverter {
+
+    public static int romanToArabic(String input) {
+        String romanNumeral = input.toUpperCase();
+        int result = 0;
+        
+        List<RomanNumeral> romanNumerals = RomanNumeral.getReverseSortedValues();
+
+        int i = 0;
+
+        while ((romanNumeral.length() > 0) && (i < romanNumerals.size())) {
+            RomanNumeral symbol = romanNumerals.get(i);
+            if (romanNumeral.startsWith(symbol.name())) {
+                result += symbol.getValue();
+                romanNumeral = romanNumeral.substring(symbol.name().length());
+            } else {
+                i++;
+            }
+        }
+        if (romanNumeral.length() > 0) {
+            throw new IllegalArgumentException(input + " cannot be converted to a Roman Numeral");
+        }
+
+        return result;
+    }
+
+    public static String arabicToRoman(int number) {
+        if ((number <= 0) || (number > 4000)) {
+            throw new IllegalArgumentException(number + " is not in range (0,4000]");
+        }
+
+        List<RomanNumeral> romanNumerals = RomanNumeral.getReverseSortedValues();
+
+        int i = 0;
+        StringBuilder sb = new StringBuilder();
+
+        while (number > 0 && i < romanNumerals.size()) {
+            RomanNumeral currentSymbol = romanNumerals.get(i);
+            if (currentSymbol.getValue() <= number) {
+                sb.append(currentSymbol.name());
+                number -= currentSymbol.getValue();
+            } else {
+                i++;
+            }
+        }
+        return sb.toString();
+    }
+}

algorithms/src/main/java/com/baeldung/algorithms/romannumerals/RomanNumeral.java

@@ -0,0 +1,26 @@
+package com.baeldung.algorithms.romannumerals;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+enum RomanNumeral {
+    I(1), IV(4), V(5), IX(9), X(10), XL(40), L(50), XC(90), C(100), CD(400), D(500), CM(900), M(1000);
+
+    private int value;
+
+    RomanNumeral(int value) {
+        this.value = value;
+    }
+
+    public int getValue() {
+        return value;
+    }
+    
+    public static List<RomanNumeral> getReverseSortedValues() {
+        return Arrays.stream(values())
+          .sorted(Comparator.comparing((RomanNumeral e) -> e.value).reversed())
+          .collect(Collectors.toList());
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/romannumerals/RomanArabicConverterUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.romannumerals;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class RomanArabicConverterUnitTest {
+
+    @Test
+    public void given2018Roman_WhenConvertingToArabic_ThenReturn2018() {
+
+        String roman2018 = "MMXVIII";
+
+        int result = RomanArabicConverter.romanToArabic(roman2018);
+
+        assertThat(result).isEqualTo(2018);
+    }
+
+    @Test
+    public void given1999Arabic_WhenConvertingToRoman_ThenReturnMCMXCIX() {
+
+        int arabic1999 = 1999;
+
+        String result = RomanArabicConverter.arabicToRoman(arabic1999);
+
+        assertThat(result).isEqualTo("MCMXCIX");
+    }
+
+}

antlr/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles: 
+
+- [Java with ANTLR](http://www.baeldung.com/java-antlr)

apache-meecrowave/pom.xml

@@ -0,0 +1,57 @@
+<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>
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-meecrowave</artifactId>
+    <version>0.0.1</version>
+    <name>apache-meecrowave</name>
+    <description>A sample REST API application with Meecrowave</description>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+    <dependencies>
+        <!-- https://mvnrepository.com/artifact/org.apache.meecrowave/meecrowave-core -->
+        <dependency>
+            <groupId>org.apache.meecrowave</groupId>
+            <artifactId>meecrowave-core</artifactId>
+            <version>1.2.1</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.meecrowave/meecrowave-jpa -->
+        <dependency>
+            <groupId>org.apache.meecrowave</groupId>
+            <artifactId>meecrowave-jpa</artifactId>
+            <version>1.2.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>okhttp</artifactId>
+            <version>3.10.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.meecrowave</groupId>
+            <artifactId>meecrowave-junit</artifactId>
+            <version>1.2.0</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/junit/junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.10</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.meecrowave</groupId>
+                <artifactId>meecrowave-maven-plugin</artifactId>
+                <version>1.2.1</version>
+            </plugin>
+        </plugins>
+    </build>
+</project>

apache-meecrowave/src/main/java/com/baeldung/meecrowave/Article.java

@@ -0,0 +1,30 @@
+package com.baeldung.meecrowave;
+
+public class Article {
+    private String name;
+    private String author;
+
+    public Article() {
+    }
+
+    public Article(String name, String author) {
+        this.author = author;
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+}

apache-meecrowave/src/main/java/com/baeldung/meecrowave/ArticleEndpoints.java

@@ -0,0 +1,32 @@
+package com.baeldung.meecrowave;
+
+import javax.enterprise.context.RequestScoped;
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.Response.Status;
+
+@RequestScoped
+@Path("article")
+public class ArticleEndpoints {
+
+    @Inject
+    ArticleService articleService;
+
+    @GET
+    public Response getArticle() {
+        return Response.ok()
+            .entity(new Article("name", "author"))
+            .build();
+
+    }
+
+    @POST
+    public Response createArticle(Article article) {
+        return Response.status(Status.CREATED)
+            .entity(articleService.createArticle(article))
+            .build();
+    }
+}

apache-meecrowave/src/main/java/com/baeldung/meecrowave/ArticleService.java

@@ -0,0 +1,10 @@
+package com.baeldung.meecrowave;
+
+import javax.enterprise.context.ApplicationScoped;
+
+@ApplicationScoped
+public class ArticleService {
+    public Article createArticle(Article article) {
+        return article;
+    }
+}

apache-meecrowave/src/main/java/com/baeldung/meecrowave/Server.java

@@ -0,0 +1,16 @@
+package com.baeldung.meecrowave;
+
+import org.apache.meecrowave.Meecrowave;
+
+public class Server {
+    public static void main(String[] args) {
+        final Meecrowave.Builder builder = new Meecrowave.Builder();
+        builder.setScanningPackageIncludes("com.baeldung.meecrowave");
+        builder.setJaxrsMapping("/api/*");
+        builder.setJsonpPrettify(true);
+
+        try (Meecrowave meecrowave = new Meecrowave(builder)) {
+            meecrowave.bake().await();
+        }
+    }
+}

apache-meecrowave/src/test/java/com/baeldung/meecrowave/ArticleEndpointsTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.meecrowave;
+
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+
+import org.apache.meecrowave.Meecrowave;
+import org.apache.meecrowave.junit.MonoMeecrowave;
+import org.apache.meecrowave.testing.ConfigurationInject;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+
+@RunWith(MonoMeecrowave.Runner.class)
+public class ArticleEndpointsTest {
+    
+    @ConfigurationInject
+    private Meecrowave.Builder config;
+    private static OkHttpClient client;
+    
+    @BeforeClass
+    public static void setup() {
+        client = new OkHttpClient();
+    }
+    
+   @Test
+    public void whenRetunedArticle_thenCorrect() throws IOException {
+        final String base = "http://localhost:"+config.getHttpPort();
+        
+        Request request = new Request.Builder()
+          .url(base+"/article")
+          .build();
+        Response response = client.newCall(request).execute();
+        assertEquals(200,  response.code());
+    }
+}

apache-solrj/src/test/java/com/baeldung/solrjava/SolrJavaLiveTest.java

@@ -12,7 +12,7 @@ import org.apache.solr.common.SolrDocumentList;
 import org.junit.Before;
 import org.junit.Test;
 
-public class SolrJavaIntegrationTest {
+public class SolrJavaLiveTest {
 
     private SolrJavaIntegration solrJavaIntegration;
 

aws-lambda/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles: 
+- [Using AWS Lambda with API Gateway](http://www.baeldung.com/aws-lambda-api-gateway)
+- [Introduction to AWS Serverless Application Model](http://www.baeldung.com/aws-serverless)

aws-lambda/sam-templates/template-implicit.yaml

@@ -0,0 +1,60 @@
+AWSTemplateFormatVersion: '2010-09-09'
+Transform: 'AWS::Serverless-2016-10-31'
+Description: Baeldung Serverless Application Model Example with Implicit API Definition
+Globals:
+  Api:
+    EndpointConfiguration: REGIONAL
+    Name: "TestAPI"
+Resources:
+  PersonTable:
+    Type: AWS::Serverless::SimpleTable
+    Properties:
+      PrimaryKey:
+          Name: id
+          Type: Number
+      TableName: Person
+  StorePersonFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleRequest
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBCrudPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        StoreApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: PUT
+  GetPersonByHTTPParamFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleGetByParam
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBReadPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        GetByPathApi:
+          Type: Api
+          Properties:
+            Path: /persons/{id}
+            Method: GET
+        GetByQueryApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: GET

aws-lambda/sam-templates/template-inline-swagger.yaml

@@ -0,0 +1,112 @@
+AWSTemplateFormatVersion: '2010-09-09'
+Transform: 'AWS::Serverless-2016-10-31'
+Description: Baeldung Serverless Application Model Example with Inline Swagger API Definition
+Resources:
+  PersonTable:
+    Type: AWS::Serverless::SimpleTable
+    Properties:
+      PrimaryKey:
+          Name: id
+          Type: Number
+      TableName: Person
+  StorePersonFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleRequest
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBCrudPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        StoreApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: PUT
+            RestApiId:
+                Ref: MyApi
+  GetPersonByHTTPParamFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleGetByParam
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBReadPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        GetByPathApi:
+          Type: Api
+          Properties:
+            Path: /persons/{id}
+            Method: GET
+            RestApiId:
+                Ref: MyApi
+        GetByQueryApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: GET
+            RestApiId:
+                Ref: MyApi
+  MyApi:
+    Type: AWS::Serverless::Api
+    Properties:
+      StageName: test
+      EndpointConfiguration: REGIONAL
+      DefinitionBody:
+        swagger: "2.0"
+        info:
+          title: "TestAPI"
+        paths:
+          /persons:
+            get:
+              parameters:
+              - name: "id"
+                in: "query"
+                required: true
+                type: "string"
+              x-amazon-apigateway-request-validator: "Validate query string parameters and\
+                \ headers"
+              x-amazon-apigateway-integration:
+                uri:
+                  Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetPersonByHTTPParamFunction.Arn}/invocations
+                responses: {}
+                httpMethod: "POST"
+                type: "aws_proxy"
+            put:
+              x-amazon-apigateway-integration:
+                uri:
+                  Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${StorePersonFunction.Arn}/invocations
+                responses: {}
+                httpMethod: "POST"
+                type: "aws_proxy"
+          /persons/{id}:
+            get:
+              parameters:
+              - name: "id"
+                in: "path"
+                required: true
+                type: "string"
+              responses: {}
+              x-amazon-apigateway-integration:
+                uri:
+                  Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetPersonByHTTPParamFunction.Arn}/invocations
+                responses: {}
+                httpMethod: "POST"
+                type: "aws_proxy"
+        x-amazon-apigateway-request-validators:
+          Validate query string parameters and headers:
+            validateRequestParameters: true
+            validateRequestBody: false

aws-lambda/src/main/java/com/baeldung/lambda/apigateway/APIDemoHandler.java

@@ -15,152 +15,107 @@ import java.io.*;
 
 public class APIDemoHandler implements RequestStreamHandler {
 
-	private JSONParser parser = new JSONParser();
-	private  static final String DYNAMODB_TABLE_NAME = System.getenv("TABLE_NAME");
+    private JSONParser parser = new JSONParser();
+    private static final String DYNAMODB_TABLE_NAME = System.getenv("TABLE_NAME");
 
-	@Override
-	public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
+    @Override
+    public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
 
-		BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
-		JSONObject responseJson = new JSONObject();
+        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+        JSONObject responseJson = new JSONObject();
 
-		AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
-		DynamoDB dynamoDb = new DynamoDB(client);
+        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
+        DynamoDB dynamoDb = new DynamoDB(client);
 
-		try {
-			JSONObject event = (JSONObject) parser.parse(reader);
+        try {
+            JSONObject event = (JSONObject) parser.parse(reader);
 
-			if (event.get("body") != null) {
+            if (event.get("body") != null) {
 
-				Person person = new Person((String) event.get("body"));
+                Person person = new Person((String) event.get("body"));
 
-				dynamoDb.getTable(DYNAMODB_TABLE_NAME)
-						.putItem(new PutItemSpec().withItem(new Item().withNumber("id", person.getId())
-								.withString("firstName", person.getFirstName())
-								.withString("lastName", person.getLastName()).withNumber("age", person.getAge())
-								.withString("address", person.getAddress())));
-			}
+                dynamoDb.getTable(DYNAMODB_TABLE_NAME)
+                    .putItem(new PutItemSpec().withItem(new Item().withNumber("id", person.getId())
+                        .withString("name", person.getName())));
+            }
 
-			JSONObject responseBody = new JSONObject();
-			responseBody.put("message", "New item created");
+            JSONObject responseBody = new JSONObject();
+            responseBody.put("message", "New item created");
 
-			JSONObject headerJson = new JSONObject();
-			headerJson.put("x-custom-header", "my custom header value");
+            JSONObject headerJson = new JSONObject();
+            headerJson.put("x-custom-header", "my custom header value");
 
-			responseJson.put("statusCode", 200);
-			responseJson.put("headers", headerJson);
-			responseJson.put("body", responseBody.toString());
+            responseJson.put("statusCode", 200);
+            responseJson.put("headers", headerJson);
+            responseJson.put("body", responseBody.toString());
 
-		} catch (ParseException pex) {
-			responseJson.put("statusCode", 400);
-			responseJson.put("exception", pex);
-		}
+        } catch (ParseException pex) {
+            responseJson.put("statusCode", 400);
+            responseJson.put("exception", pex);
+        }
 
-		OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
-		writer.write(responseJson.toString());
-		writer.close();
-	}
+        OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
+        writer.write(responseJson.toString());
+        writer.close();
+    }
 
-	public void handleGetByPathParam(InputStream inputStream, OutputStream outputStream, Context context)
-			throws IOException {
+    public void handleGetByParam(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
 
-		BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
-		JSONObject responseJson = new JSONObject();
+        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+        JSONObject responseJson = new JSONObject();
 
-		AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
-		DynamoDB dynamoDb = new DynamoDB(client);
+        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
+        DynamoDB dynamoDb = new DynamoDB(client);
 
-		Item result = null;
-		try {
-			JSONObject event = (JSONObject) parser.parse(reader);
-			JSONObject responseBody = new JSONObject();
+        Item result = null;
+        try {
+            JSONObject event = (JSONObject) parser.parse(reader);
+            JSONObject responseBody = new JSONObject();
 
-			if (event.get("pathParameters") != null) {
+            if (event.get("pathParameters") != null) {
 
-				JSONObject pps = (JSONObject) event.get("pathParameters");
-				if (pps.get("id") != null) {
+                JSONObject pps = (JSONObject) event.get("pathParameters");
+                if (pps.get("id") != null) {
 
-					int id = Integer.parseInt((String) pps.get("id"));
-					result = dynamoDb.getTable(DYNAMODB_TABLE_NAME).getItem("id", id);
-				}
+                    int id = Integer.parseInt((String) pps.get("id"));
+                    result = dynamoDb.getTable(DYNAMODB_TABLE_NAME)
+                        .getItem("id", id);
+                }
 
-			}
-			if (result != null) {
+            } else if (event.get("queryStringParameters") != null) {
 
-				Person person = new Person(result.toJSON());
-				responseBody.put("Person", person);
-				responseJson.put("statusCode", 200);
-			} else {
+                JSONObject qps = (JSONObject) event.get("queryStringParameters");
+                if (qps.get("id") != null) {
 
-				responseBody.put("message", "No item found");
-				responseJson.put("statusCode", 404);
-			}
+                    int id = Integer.parseInt((String) qps.get("id"));
+                    result = dynamoDb.getTable(DYNAMODB_TABLE_NAME)
+                        .getItem("id", id);
+                }
+            }
+            if (result != null) {
 
-			JSONObject headerJson = new JSONObject();
-			headerJson.put("x-custom-header", "my custom header value");
+                Person person = new Person(result.toJSON());
+                responseBody.put("Person", person);
+                responseJson.put("statusCode", 200);
+            } else {
 
-			responseJson.put("headers", headerJson);
-			responseJson.put("body", responseBody.toString());
+                responseBody.put("message", "No item found");
+                responseJson.put("statusCode", 404);
+            }
 
-		} catch (ParseException pex) {
-			responseJson.put("statusCode", 400);
-			responseJson.put("exception", pex);
-		}
+            JSONObject headerJson = new JSONObject();
+            headerJson.put("x-custom-header", "my custom header value");
 
-		OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
-		writer.write(responseJson.toString());
-		writer.close();
-	}
+            responseJson.put("headers", headerJson);
+            responseJson.put("body", responseBody.toString());
 
-	public void handleGetByQueryParam(InputStream inputStream, OutputStream outputStream, Context context)
-			throws IOException {
-
-		BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
-		JSONObject responseJson = new JSONObject();
-
-		AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
-		DynamoDB dynamoDb = new DynamoDB(client);
-
-		Item result = null;
-		try {
-			JSONObject event = (JSONObject) parser.parse(reader);
-			JSONObject responseBody = new JSONObject();
-
-			if (event.get("queryStringParameters") != null) {
-
-				JSONObject qps = (JSONObject) event.get("queryStringParameters");
-				if (qps.get("id") != null) {
-
-					int id = Integer.parseInt((String) qps.get("id"));
-					result = dynamoDb.getTable(DYNAMODB_TABLE_NAME).getItem("id", id);
-				}
-			}
-
-			if (result != null) {
-
-				Person person = new Person(result.toJSON());
-				responseBody.put("Person", person);
-				responseJson.put("statusCode", 200);
-			} else {
-
-				responseBody.put("message", "No item found");
-				responseJson.put("statusCode", 404);
-			}
-
-			JSONObject headerJson = new JSONObject();
-			headerJson.put("x-custom-header", "my custom header value");
-
-			responseJson.put("headers", headerJson);
-			responseJson.put("body", responseBody.toString());
-
-		} catch (ParseException pex) {
-			responseJson.put("statusCode", 400);
-			responseJson.put("exception", pex);
-		}
-
-		OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
-		writer.write(responseJson.toString());
-		writer.close();
-	}
+        } catch (ParseException pex) {
+            responseJson.put("statusCode", 400);
+            responseJson.put("exception", pex);
+        }
 
+        OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
+        writer.write(responseJson.toString());
+        writer.close();
+    }
 }

aws-lambda/src/main/java/com/baeldung/lambda/apigateway/model/Person.java

@@ -5,64 +5,34 @@ import com.google.gson.GsonBuilder;
 
 public class Person {
 
-	private int id;
-	private String firstName;
-	private String lastName;
-	private int age;
-	private String address;
+    private int id;
+    private String name;
 
-	public Person(String json) {
-		Gson gson = new Gson();
-		Person request = gson.fromJson(json, Person.class);
-		this.id = request.getId();
-		this.firstName = request.getFirstName();
-		this.lastName = request.getLastName();
-		this.age = request.getAge();
-		this.address = request.getAddress();
-	}
+    public Person(String json) {
+        Gson gson = new Gson();
+        Person request = gson.fromJson(json, Person.class);
+        this.id = request.getId();
+        this.name = request.getName();
+    }
 
-	public String toString() {
-		final Gson gson = new GsonBuilder().setPrettyPrinting().create();
-		return gson.toJson(this);
-	}
+    public String toString() {
+        final Gson gson = new GsonBuilder().setPrettyPrinting().create();
+        return gson.toJson(this);
+    }
 
-	public int getId() {
-		return id;
-	}
+    public int getId() {
+        return id;
+    }
 
-	public void setId(int id) {
-		this.id = id;
-	}
+    public void setId(int id) {
+        this.id = id;
+    }
 
-	public String getFirstName() {
-		return firstName;
-	}
+    public String getName() {
+        return name;
+    }
 
-	public void setFirstName(String firstName) {
-		this.firstName = firstName;
-	}
-
-	public String getLastName() {
-		return lastName;
-	}
-
-	public void setLastName(String lastName) {
-		this.lastName = lastName;
-	}
-
-	public int getAge() {
-		return age;
-	}
-
-	public void setAge(int age) {
-		this.age = age;
-	}
-
-	public String getAddress() {
-		return address;
-	}
-
-	public void setAddress(String address) {
-		this.address = address;
-	}
+    public void setName(String name) {
+        this.name = name;
+    }
 }

baeldung-pmd-rules.xml

@@ -3,8 +3,8 @@
 	xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd" 
 	xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">
 	<description>Baeldung custom PMD rules</description>
-	<rule name="UnitTestMustFollowNamingConventionRule" message="Test class name doesn't follow the naming convention" class="org.baeldung.pmd.UnitTestNamingConventionRule">
+	<rule name="UnitTestMustFollowNamingConventionRule" message="Unit test class names need to end in 'UnitTest', integration tests with 'IntegrationTest', etc " class="org.baeldung.pmd.UnitTestNamingConventionRule">
 		<description>Test does not follow Baeldung naming convention</description>
 		<priority>3</priority>
 	</rule>
-</ruleset>
+</ruleset>

cdi/README.md

@@ -1,2 +1,3 @@
 ### Relevant Articles:
 - [CDI Interceptor vs Spring AspectJ](http://www.baeldung.com/cdi-interceptor-vs-spring-aspectj)
+- [An Introduction to CDI (Contexts and Dependency Injection) in Java](http://www.baeldung.com/java-ee-cdi)

core-java-8/README.md

@@ -54,3 +54,5 @@
 - [An Introduction to Java.util.Hashtable Class](http://www.baeldung.com/java-hash-table)
 - [Method Parameter Reflection in Java](http://www.baeldung.com/java-parameter-reflection)
 - [Java 8 Unsigned Arithmetic Support](http://www.baeldung.com/java-unsigned-arithmetic)
+- [How to Get the Start and the End of a Day using Java](http://www.baeldung.com/java-day-start-end)
+- [Generalized Target-Type Inference in Java](http://www.baeldung.com/java-generalized-target-type-inference)

core-java-8/src/main/java/com/baeldung/datetime/AddHoursToDate.java

@@ -0,0 +1,54 @@
+package com.baeldung.datetime;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.Date;
+
+import org.apache.commons.lang3.time.DateUtils;
+
+public class AddHoursToDate {
+
+    public Date addHoursToJavaUtilDate(Date date, int hours) {
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(date);
+        calendar.add(Calendar.HOUR_OF_DAY, hours);
+        return calendar.getTime();
+    }
+
+    public Date addHoursToDateUsingInstant(Date date, int hours) {
+        return Date.from(date.toInstant()
+            .plus(Duration.ofHours(hours)));
+    }
+
+    public LocalDateTime addHoursToLocalDateTime(LocalDateTime localDateTime, int hours) {
+        return localDateTime.plusHours(hours);
+    }
+
+    public LocalDateTime subtractHoursToLocalDateTime(LocalDateTime localDateTime, int hours) {
+        return localDateTime.minusHours(hours);
+    }
+
+    public ZonedDateTime addHoursToZonedDateTime(ZonedDateTime zonedDateTime, int hours) {
+        return zonedDateTime.plusHours(hours);
+    }
+
+    public ZonedDateTime subtractHoursToZonedDateTime(ZonedDateTime zonedDateTime, int hours) {
+        return zonedDateTime.minusHours(hours);
+    }
+
+    public Instant addHoursToInstant(Instant instant, int hours) {
+        return instant.plus(hours, ChronoUnit.HOURS);
+    }
+
+    public Instant subtractHoursToInstant(Instant instant, int hours) {
+        return instant.minus(hours, ChronoUnit.HOURS);
+    }
+
+    public Date addHoursWithApacheCommons(Date date, int hours) {
+        return DateUtils.addHours(date, hours);
+    }
+}

core-java-8/src/test/java/com/baeldung/datetime/AddHoursToDateUnitTest.java

@@ -0,0 +1,116 @@
+package com.baeldung.datetime;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.Month;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+
+import org.junit.Test;
+
+public class AddHoursToDateUnitTest {
+
+    private final AddHoursToDate addHoursToDateObj = new AddHoursToDate();
+
+    @Test
+    public void givenJavaUtilDate_whenPositiveHours_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToJavaUtilDate(actualDate, 2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenNegativeHours_thenMinusHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 3, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToJavaUtilDate(actualDate, -2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingToInstantAndPostiveHours_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToDateUsingInstant(actualDate, 2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingToInstantAndNegativeHours_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 3, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToDateUsingInstant(actualDate, -2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenLocalDateTime_whenUsingAddHoursToLocalDateTime_thenAddHours() {
+        LocalDateTime actualDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 5, 0);
+        LocalDateTime expectedDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 7, 0);
+
+        assertThat(addHoursToDateObj.addHoursToLocalDateTime(actualDateTime, 2)).isEqualTo(expectedDateTime);
+    }
+
+    @Test
+    public void givenLocalDateTime_whenUsingMinusHoursToLocalDateTime_thenMinusHours() {
+        LocalDateTime actualDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 5, 0);
+        LocalDateTime expectedDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 3, 0);
+
+        assertThat(addHoursToDateObj.subtractHoursToLocalDateTime(actualDateTime, 2)).isEqualTo(expectedDateTime);
+    }
+
+    @Test
+    public void givenZonedDateTime_whenUsingAddHoursToZonedDateTime_thenAddHours() {
+        ZonedDateTime actualZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 5, 0), ZoneId.systemDefault());
+        ZonedDateTime expectedZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 7, 0), ZoneId.systemDefault());
+
+        assertThat(addHoursToDateObj.addHoursToZonedDateTime(actualZonedDateTime, 2)).isEqualTo(expectedZonedDateTime);
+    }
+
+    @Test
+    public void givenZonedDateTime_whenUsingMinusHoursToZonedDateTime_thenMinusHours() {
+        ZonedDateTime actualZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 5, 0), ZoneId.systemDefault());
+        ZonedDateTime expectedZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 3, 0), ZoneId.systemDefault());
+
+        assertThat(addHoursToDateObj.subtractHoursToZonedDateTime(actualZonedDateTime, 2)).isEqualTo(expectedZonedDateTime);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingPositiveHrsAndAddHoursWithApacheCommons_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursWithApacheCommons(actualDate, 2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingNegativeHrsAndAddHoursWithApacheCommons_thenMinusHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursWithApacheCommons(actualDate, -2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenInstant_whenUsingAddHoursToInstant_thenAddHours() {
+        Instant actualValue = Instant.parse("2018-06-25T05:12:35Z");
+        Instant expectedValue = Instant.parse("2018-06-25T07:12:35Z");
+
+        assertThat(addHoursToDateObj.addHoursToInstant(actualValue, 2)).isEqualTo(expectedValue);
+    }
+
+    @Test
+    public void givenInstant_whenUsingSubtractHoursToInstant_thenMinusHours() {
+        Instant actualValue = Instant.parse("2018-06-25T07:12:35Z");
+        Instant expectedValue = Instant.parse("2018-06-25T05:12:35Z");
+
+        assertThat(addHoursToDateObj.subtractHoursToInstant(actualValue, 2)).isEqualTo(expectedValue);
+    }
+
+}

core-java-8/src/test/java/com/baeldung/fileToBase64StringConversion/FileToBase64StringConversionUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.fileToBase64StringConversion;
+
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Base64;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Test;
+
+public class FileToBase64StringConversionUnitTest {
+
+    private String inputFilePath = "test_image.jpg";
+    private String outputFilePath = "test_image_copy.jpg";
+
+    @Test
+    public void fileToBase64StringConversion() throws IOException {
+        //load file from /src/test/resources
+        ClassLoader classLoader = getClass().getClassLoader();
+        File inputFile = new File(classLoader
+          .getResource(inputFilePath)
+          .getFile());
+
+        byte[] fileContent = FileUtils.readFileToByteArray(inputFile);
+        String encodedString = Base64
+          .getEncoder()
+          .encodeToString(fileContent);
+
+        //create output file
+        File outputFile = new File(inputFile
+          .getParentFile()
+          .getAbsolutePath() + File.pathSeparator + outputFilePath);
+
+        // decode the string and write to file
+        byte[] decodedBytes = Base64
+          .getDecoder()
+          .decode(encodedString);
+        FileUtils.writeByteArrayToFile(outputFile, decodedBytes);
+
+        assertTrue(FileUtils.contentEquals(inputFile, outputFile));
+    }
+}

core-java-collections/src/main/java/com/baeldung/java/list/ReverseIterator.java

@@ -0,0 +1,80 @@
+package com.baeldung.java.list;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.ListIterator;
+
+import org.apache.commons.collections4.iterators.ReverseListIterator;
+
+import com.google.common.collect.Lists;
+
+/**
+ * Provides methods for iterating backward over a list.
+ */
+public class ReverseIterator {
+
+    /**
+     * Iterate using the for loop.
+     *
+     * @param list the list
+     */
+    public void iterateUsingForLoop(final List<String> list) {
+
+        for (int i = list.size(); i-- > 0; ) {
+            System.out.println(list.get(i));
+        }
+    }
+
+    /**
+     * Iterate using the Java {@link ListIterator}.
+     *
+     * @param list the list
+     */
+    public void iterateUsingListIterator(final List<String> list) {
+
+        final ListIterator listIterator = list.listIterator(list.size());
+        while (listIterator.hasPrevious()) {
+            System.out.println(listIterator.previous());
+        }
+    }
+
+    /**
+     * Iterate using Java {@link Collections} API.
+     *
+     * @param list the list
+     */
+    public void iterateUsingCollections(final List<String> list) {
+
+        Collections.reverse(list);
+        for (final String item : list) {
+            System.out.println(item);
+        }
+    }
+
+    /**
+     * Iterate using Apache Commons {@link ReverseListIterator}.
+     *
+     * @param list the list
+     */
+    public void iterateUsingApacheReverseListIterator(final List<String> list) {
+
+        final ReverseListIterator listIterator = new ReverseListIterator(list);
+        while (listIterator.hasNext()) {
+            System.out.println(listIterator.next());
+        }
+    }
+
+    /**
+     * Iterate using Guava {@link Lists} API.
+     *
+     * @param list the list
+     */
+    public void iterateUsingGuava(final List<String> list) {
+
+        final List<String> reversedList = Lists.reverse(list);
+        for (final String item : reversedList) {
+            System.out.println(item);
+        }
+    }
+
+}

core-java-collections/src/test/java/com/baeldung/java/list/ReverseIteratorUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.java.list;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.ListIterator;
+
+import org.apache.commons.collections4.iterators.ReverseListIterator;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import com.google.common.collect.Lists;
+
+public class ReverseIteratorUnitTest {
+
+    private final ReverseIterator reverseIterator = new ReverseIterator();
+
+    private List<String> list;
+
+    private final String originalString = "ABCDE";
+
+    @BeforeEach
+    void setUp() {
+
+        list = Lists.newArrayList("A", "B", "C", "D", "E");
+    }
+
+    @Test
+    void whenIteratingUsingForLoop_thenCorrect() {
+
+        String reverseString = "";
+        for (int i = list.size(); i-- > 0; ) {
+            reverseString += list.get(i);
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+    }
+
+    @Test
+    void whenIteratingUsingListIterator_thenCorrect() {
+
+        String reverseString = "";
+        final ListIterator listIterator = list.listIterator(list.size());
+        while (listIterator.hasPrevious()) {
+            reverseString += listIterator.previous();
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+    }
+
+    @Test
+    void whenIteratingUsingCollections_thenCorrect() {
+
+        String reverseString = "";
+        Collections.reverse(list);
+        for (final String item : list) {
+            reverseString += item;
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+
+        assertEquals("E", list.get(0));
+    }
+
+    @Test
+    void whenIteratingUsingApacheReverseListIterator_thenCorrect() {
+
+        String reverseString = "";
+        final ReverseListIterator listIterator = new ReverseListIterator(list);
+        while (listIterator.hasNext()) {
+            reverseString += listIterator.next();
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+    }
+
+    @Test
+    void whenIteratingUsingGuava_thenCorrect() {
+
+        String reverseString = "";
+        final List<String> reversedList = Lists.reverse(list);
+        for (final String item : reversedList) {
+            reverseString += item;
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+
+        assertEquals("A", list.get(0));
+    }
+}

core-java-io/src/main/java/com/baeldung/symlink/SymLinkExample.java

@@ -0,0 +1,54 @@
+package com.baeldung.symlink;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.DirectoryStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import static java.nio.file.StandardOpenOption.*;
+import java.util.stream.IntStream;
+
+public class SymLinkExample {
+
+    public void createSymbolicLink(Path link, Path target) throws IOException {
+        if (Files.exists(link)) {
+            Files.delete(link);
+        }
+        Files.createSymbolicLink(link, target);
+    }
+
+    public void createHardLink(Path link, Path target) throws IOException {
+        if (Files.exists(link)) {
+            Files.delete(link);
+        }
+        Files.createLink(link, target);
+    }
+
+    public Path createTextFile() throws IOException {
+        byte[] content = IntStream.range(0, 10000)
+            .mapToObj(i -> i + System.lineSeparator())
+            .reduce("", String::concat)
+            .getBytes(StandardCharsets.UTF_8);
+        Path filePath = Paths.get(".", "target_link.txt");
+        Files.write(filePath, content, CREATE, TRUNCATE_EXISTING);
+        return filePath;
+    }
+
+    public void printLinkFiles(Path path) throws IOException {
+        try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
+            for (Path file : stream) {
+                if (Files.isDirectory(file)) {
+                    printLinkFiles(file);
+                } else if (Files.isSymbolicLink(file)) {
+                    System.out.format("File link '%s' with target '%s'%n", file, Files.readSymbolicLink(file));
+                }
+            }
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        new SymLinkExample().printLinkFiles(Paths.get("."));
+    }
+
+}

core-java-io/src/test/java/com/baeldung/symlink/SymLinkExampleUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.symlink;
+
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.junit.Test;
+
+public class SymLinkExampleUnitTest {
+
+    @Test
+    public void whenUsingFiles_thenCreateSymbolicLink() throws IOException {
+        SymLinkExample example = new SymLinkExample();
+        Path filePath = example.createTextFile();
+        Path linkPath = Paths.get(".", "symbolic_link.txt");
+        example.createSymbolicLink(linkPath, filePath);
+        assertTrue(Files.isSymbolicLink(linkPath));
+    }
+
+    @Test
+    public void whenUsingFiles_thenCreateHardLink() throws IOException {
+        SymLinkExample example = new SymLinkExample();
+        Path filePath = example.createTextFile();
+        Path linkPath = Paths.get(".", "hard_link.txt");
+        example.createHardLink(linkPath, filePath);
+        assertFalse(Files.isSymbolicLink(linkPath));
+        assertEquals(filePath.toFile()
+            .length(),
+            linkPath.toFile()
+                .length());
+    }
+
+}