Merge pull request #1 from eugenp/master

Syncing

algorithms-miscellaneous-1/README.md

@@ -15,3 +15,5 @@
 - [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
 - [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
 - [Java Two Pointer Technique](https://www.baeldung.com/java-two-pointer-technique)
+- [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
+- [Implementing Simple State Machines with Java Enums](https://www.baeldung.com/java-enum-simple-state-machine)

apache-spark/README.md

@@ -1,3 +1,4 @@
 ### Relevant articles
 
 - [Introduction to Apache Spark](http://www.baeldung.com/apache-spark)
+- [Building a Data Pipeline with Kafka, Spark Streaming and Cassandra](https://www.baeldung.com/kafka-spark-data-pipeline)

core-groovy/src/main/groovy/com/baeldung/strings/Concatenate.groovy

@@ -0,0 +1,43 @@
+package com.baeldung.strings;
+
+class Concatenate {
+    String first = 'Hello'
+    String last = 'Groovy'
+  
+    String doSimpleConcat() {
+        return 'My name is ' + first + ' ' + last
+    }
+
+    String doConcatUsingGString() {
+        return "My name is $first $last"
+    }
+
+    String doConcatUsingGStringClosures() {
+        return "My name is ${-> first} ${-> last}"
+    }
+
+    String doConcatUsingStringConcatMethod() {
+        return 'My name is '.concat(first).concat(' ').concat(last)
+    }
+
+    String doConcatUsingLeftShiftOperator() {
+        return 'My name is ' << first << ' ' << last
+    }
+    
+    String doConcatUsingArrayJoinMethod() {
+        return ['My name is', first, last].join(' ')
+    }
+
+    String doConcatUsingArrayInjectMethod() {
+        return  [first,' ', last]
+          .inject(new StringBuffer('My name is '), { initial, name -> initial.append(name); return initial }).toString()
+    }
+ 
+    String doConcatUsingStringBuilder() {
+        return new StringBuilder().append('My name is ').append(first).append(' ').append(last)
+    }
+
+    String doConcatUsingStringBuffer() {
+        return new StringBuffer().append('My name is ').append(first).append(' ').append(last)
+    }
+}

core-groovy/src/test/groovy/com/baeldung/strings/ConcatenateTest.groovy

@@ -0,0 +1,101 @@
+import com.baeldung.strings.Concatenate;
+
+class ConcatenateTest extends GroovyTestCase {
+    
+    void testSimpleConcat() {
+        def name = new Concatenate()
+        name.first = 'Joe';
+        name.last = 'Smith';
+        def expected = 'My name is Joe Smith'
+        assertToString(name.doSimpleConcat(), expected)
+    }
+    
+    void testConcatUsingGString() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingGString(), expected)
+    }
+    
+    void testConcatUsingGStringClosures() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingGStringClosures(), expected)
+    }
+    
+    void testConcatUsingStringConcatMethod() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingStringConcatMethod(), expected)
+    }
+
+    void testConcatUsingLeftShiftOperator() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingLeftShiftOperator(), expected)
+    }
+
+    void testConcatUsingArrayJoinMethod() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingArrayJoinMethod(), expected)
+    }
+
+    void testConcatUsingArrayInjectMethod() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingArrayInjectMethod(), expected)
+    }
+
+    void testConcatUsingStringBuilder() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingStringBuilder(), expected)
+    }
+
+    void testConcatUsingStringBuffer() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingStringBuffer(), expected)
+    }
+
+    void testConcatMultilineUsingStringConcatMethod() {
+        def name = new Concatenate()
+        name.first = '''Joe
+                        Smith
+                        ''';
+        name.last = 'Junior';
+        def expected = '''My name is Joe
+                        Smith
+                         Junior''';
+        assertToString(name.doConcatUsingStringConcatMethod(), expected)
+    }
+
+    void testGStringvsClosure(){
+        def first = "Joe";
+        def last = "Smith";
+        def eagerGString = "My name is $first $last"
+        def lazyGString = "My name is ${-> first} ${-> last}"
+
+        assert eagerGString == "My name is Joe Smith"
+        assert lazyGString == "My name is Joe Smith"
+        first = "David";
+        assert eagerGString == "My name is Joe Smith"
+        assert lazyGString == "My name is David Smith"
+    }  
+}

core-java-11/README.md

@@ -3,3 +3,4 @@
 - [Java 11 Single File Source Code](https://www.baeldung.com/java-single-file-source-code)
 - [Java 11 Local Variable Syntax for Lambda Parameters](https://www.baeldung.com/java-var-lambda-params)
 - [Java 11 String API Additions](https://www.baeldung.com/java-11-string-api)
+- [Java 11 Nest Based Access Control](https://www.baeldung.com/java-nest-based-access-control)

core-java-8/src/test/java/com/baeldung/collectors/Java8CollectorsUnitTest.java

@@ -39,6 +39,7 @@ import static org.assertj.core.api.Assertions.assertThatThrownBy;
 public class Java8CollectorsUnitTest {
 
     private final List<String> givenList = Arrays.asList("a", "bb", "ccc", "dd");
+    private final List<String> listWithDuplicates = Arrays.asList("a", "bb", "c", "d", "bb");
 
     @Test
     public void whenCollectingToList_shouldCollectToList() throws Exception {
@@ -48,12 +49,19 @@ public class Java8CollectorsUnitTest {
     }
 
     @Test
-    public void whenCollectingToList_shouldCollectToSet() throws Exception {
+    public void whenCollectingToSet_shouldCollectToSet() throws Exception {
         final Set<String> result = givenList.stream().collect(toSet());
 
         assertThat(result).containsAll(givenList);
     }
 
+    @Test
+    public void givenContainsDuplicateElements_whenCollectingToSet_shouldAddDuplicateElementsOnlyOnce() throws Exception {
+        final Set<String> result = listWithDuplicates.stream().collect(toSet());
+
+        assertThat(result).hasSize(4);
+    }
+
     @Test
     public void whenCollectingToCollection_shouldCollectToCollection() throws Exception {
         final List<String> result = givenList.stream().collect(toCollection(LinkedList::new));
@@ -83,6 +91,13 @@ public class Java8CollectorsUnitTest {
         assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("ccc", 3).containsEntry("dd", 2);
     }
 
+    @Test
+    public void givenContainsDuplicateElements_whenCollectingToMap_shouldThrowException() throws Exception {
+        assertThatThrownBy(() -> {
+            listWithDuplicates.stream().collect(toMap(Function.identity(), String::length));
+        }).isInstanceOf(IllegalStateException.class);
+    }
+
     @Test
     public void whenCollectingAndThen_shouldCollect() throws Exception {
         final List<String> result = givenList.stream().collect(collectingAndThen(toList(), ImmutableList::copyOf));

core-java-9/README.md

@@ -26,3 +26,4 @@
 - [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap)
 - [Java 9 Platform Logging API](https://www.baeldung.com/java-9-logging-api)
 - [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
+- [Immutable Set in Java](https://www.baeldung.com/java-immutable-set)

core-java-arrays/README.md

@@ -14,3 +14,4 @@
 - [Array Operations in Java](http://www.baeldung.com/java-common-array-operations)
 - [Intersection Between two Integer Arrays](https://www.baeldung.com/java-array-intersection)
 - [Sorting Arrays in Java](https://www.baeldung.com/java-sorting-arrays)
+- [Convert a Float to a Byte Array in Java](https://www.baeldung.com/java-convert-float-to-byte-array)

core-java-collections-list/pom.xml

@@ -36,6 +36,22 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
+
+        <dependency>
+            <groupId>net.sf.trove4j</groupId>
+            <artifactId>trove4j</artifactId>
+            <version>3.0.2</version>
+        </dependency>
+        <dependency>
+            <groupId>it.unimi.dsi</groupId>
+            <artifactId>fastutil</artifactId>
+            <version>8.1.0</version>
+        </dependency>
+        <dependency>
+            <groupId>colt</groupId>
+            <artifactId>colt</artifactId>
+            <version>1.2.0</version>
+        </dependency>
     </dependencies>
 
     <properties>

core-java-collections-list/src/main/java/com/baeldung/list/primitive/PrimitiveCollections.java

@@ -0,0 +1,52 @@
+package com.baeldung.list.primitive;
+
+import com.google.common.primitives.ImmutableIntArray;
+import com.google.common.primitives.Ints;
+import gnu.trove.list.array.TIntArrayList;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.OptionalDouble;
+import java.util.function.IntPredicate;
+import java.util.stream.IntStream;
+
+public class PrimitiveCollections {
+
+    public static void main(String[] args) {
+
+        int[] primitives = new int[] {5, 10, 0, 2, -8};
+
+        guavaPrimitives(primitives);
+
+        intStream(primitives);
+
+        TIntArrayList tList = new TIntArrayList(primitives);
+
+        cern.colt.list.IntArrayList coltList = new cern.colt.list.IntArrayList(primitives);
+
+        IntArrayList fastUtilList = new IntArrayList(primitives);
+
+        System.out.println(tList);
+
+        System.out.println(coltList);
+
+        System.out.println(fastUtilList);
+    }
+
+    private static void intStream(int[] primitives) {
+
+        IntStream stream = IntStream.of(5, 10, 0, 2, -8);
+
+        IntStream newStream = IntStream.of(primitives);
+
+        OptionalDouble average = stream.filter(i -> i > 0).average();
+    }
+
+
+    private static void guavaPrimitives(int[] primitives) {
+
+        ImmutableIntArray immutableIntArray = ImmutableIntArray.builder().addAll(primitives).build();
+        System.out.println(immutableIntArray);
+    }
+}

core-java-collections/README.md

@@ -31,3 +31,4 @@
 - [A Guide to EnumMap](https://www.baeldung.com/java-enum-map)
 - [A Guide to Iterator in Java](http://www.baeldung.com/java-iterator)
 - [Differences Between HashMap and Hashtable](https://www.baeldung.com/hashmap-hashtable-differences)
+- [Java ArrayList vs Vector](https://www.baeldung.com/java-arraylist-vs-vector)

core-java-io/README.md

@@ -36,4 +36,7 @@
 - [Reading a CSV File into an Array](https://www.baeldung.com/java-csv-file-array)
 - [Guide to BufferedReader](https://www.baeldung.com/java-buffered-reader)
 - [How to Get the File Extension of a File in Java](http://www.baeldung.com/java-file-extension)
-- [Getting a File’s Mime Type in Java](http://www.baeldung.com/java-file-mime-type)
+- [Getting a File’s Mime Type in Java](http://www.baeldung.com/java-file-mime-type)
+- [Create a Directory in Java](https://www.baeldung.com/java-create-directory)
+- [How to Write to a CSV File in Java](https://www.baeldung.com/java-csv)
+- [List Files in a Directory in Java](https://www.baeldung.com/java-list-directory-files)

core-java-lang-syntax/README.md

@@ -16,4 +16,5 @@
 - [Quick Guide to java.lang.System](http://www.baeldung.com/java-lang-system)
 - [Java Switch Statement](https://www.baeldung.com/java-switch)
 - [The Modulo Operator in Java](https://www.baeldung.com/modulo-java)
-- [Ternary Operator In Java](https://www.baeldung.com/java-ternary-operator)
+- [Ternary Operator In Java](https://www.baeldung.com/java-ternary-operator)
+- [Java instanceof Operator](https://www.baeldung.com/java-instanceof)

core-java-lang/README.md

@@ -34,4 +34,10 @@
 - [“Sneaky Throws” in Java](http://www.baeldung.com/java-sneaky-throws)
 - [Retrieving a Class Name in Java](https://www.baeldung.com/java-class-name)
 - [Java Compound Operators](https://www.baeldung.com/java-compound-operators)
-- [Guide to Java Packages](https://www.baeldung.com/java-packages)
+- [Guide to Java Packages](https://www.baeldung.com/java-packages)
+- [The Java Native Keyword and Methods](https://www.baeldung.com/java-native)
+- [If-Else Statement in Java](https://www.baeldung.com/java-if-else)
+- [Control Structures in Java](https://www.baeldung.com/java-control-structures)
+- [Java Interfaces](https://www.baeldung.com/java-interfaces)
+- [Attaching Values to Java Enum](https://www.baeldung.com/java-enum-values)
+- [Variable Scope in Java](https://www.baeldung.com/java-variable-scope)

core-java-lang/src/main/java/com/baeldung/scope/BracketScopeExample.java

@@ -1,4 +1,4 @@
-package org.baeldung.variable.scope.examples;
+package com.baeldung.scope;
 
 public class BracketScopeExample {
 

core-java-lang/src/main/java/com/baeldung/scope/ClassScopeExample.java

@@ -1,4 +1,4 @@
-package org.baeldung.variable.scope.examples;
+package com.baeldung.scope;
 
 public class ClassScopeExample {
 

core-java-lang/src/main/java/com/baeldung/scope/LoopScopeExample.java

@@ -1,4 +1,4 @@
-package org.baeldung.variable.scope.examples;
+package com.baeldung.scope;
 
 import java.util.Arrays;
 import java.util.List;

core-java-lang/src/main/java/com/baeldung/scope/MethodScopeExample.java

@@ -1,4 +1,4 @@
-package org.baeldung.variable.scope.examples;
+package com.baeldung.scope;
 
 public class MethodScopeExample {
 

core-java-lang/src/main/java/com/baeldung/scope/NestedScopesExample.java

@@ -1,4 +1,4 @@
-package org.baeldung.variable.scope.examples;
+package com.baeldung.scope;
 
 public class NestedScopesExample {
 

core-java-lang/src/test/java/com/baeldung/java/enumiteration/EnumIterationExamples.java

@@ -1,18 +1,43 @@
 package com.baeldung.java.enumiteration;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.EnumSet;
+import java.util.List;
+
 
 public class EnumIterationExamples {
 	public static void main(String[] args) {
-		System.out.println("Enum iteration using forEach:");
+		System.out.println("Enum iteration using EnumSet:");
 		EnumSet.allOf(DaysOfWeekEnum.class).forEach(day -> System.out.println(day));
 
 		System.out.println("Enum iteration using Stream:");
 		DaysOfWeekEnum.stream().filter(d -> d.getTypeOfDay().equals("off")).forEach(System.out::println);
 
-		System.out.println("Enum iteration using for loop:");
+		System.out.println("Enum iteration using a for loop:");
 		for (DaysOfWeekEnum day : DaysOfWeekEnum.values()) {
 			System.out.println(day);
 		}
+		
+		System.out.println("Enum iteration using Arrays.asList():");
+	        Arrays.asList(DaysOfWeekEnum.values()).forEach(day -> System.out.println(day));
+	        
+	        System.out.println("Add Enum values to ArrayList:");
+	        List<DaysOfWeekEnum> days = new ArrayList<>();
+                days.add(DaysOfWeekEnum.FRIDAY);
+                days.add(DaysOfWeekEnum.SATURDAY);
+                days.add(DaysOfWeekEnum.SUNDAY);
+                for (DaysOfWeekEnum day : days) {
+                    System.out.println(day);
+                }
+                System.out.println("Remove SATURDAY from the list:");
+                days.remove(DaysOfWeekEnum.SATURDAY); 
+                if (!days.contains(DaysOfWeekEnum.SATURDAY)) { 
+                    System.out.println("Saturday is no longer in the list"); 
+                }
+                for (DaysOfWeekEnum day : days) {
+                    System.out.println(day);
+                }
+
 	}
 }

core-java-perf/README.md

@@ -5,4 +5,5 @@
 - [Different Ways to Capture Java Heap Dumps](https://www.baeldung.com/java-heap-dump-capture)
 - [Understanding Memory Leaks in Java](https://www.baeldung.com/java-memory-leaks)
 - [OutOfMemoryError: GC Overhead Limit Exceeded](http://www.baeldung.com/java-gc-overhead-limit-exceeded)
-- [Basic Introduction to JMX](http://www.baeldung.com/java-management-extensions)
+- [Basic Introduction to JMX](http://www.baeldung.com/java-management-extensions)
+- [Monitoring Java Applications with Flight Recorder](https://www.baeldung.com/java-flight-recorder-monitoring)

core-java-security/README.md

@@ -8,4 +8,5 @@
 - [Encrypting and Decrypting Files in Java](http://www.baeldung.com/java-cipher-input-output-stream)
 - [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
 - [SSL Handshake Failures](https://www.baeldung.com/java-ssl-handshake-failures)
-- [SHA-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)
+- [SHA-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)
+- [Enabling TLS v1.2 in Java 7](https://www.baeldung.com/java-7-tls-v12)

core-java-security/pom.xml

@@ -44,8 +44,8 @@
 
         <!-- util -->
         <commons-lang3.version>3.8.1</commons-lang3.version>
-        <bouncycastle.version>1.55</bouncycastle.version>
-        <commons-codec.version>1.10</commons-codec.version>
+        <bouncycastle.version>1.60</bouncycastle.version>
+        <commons-codec.version>1.11</commons-codec.version>
 
         <!-- testing -->
         <assertj-core.version>3.10.0</assertj-core.version>

core-java-security/src/main/java/com/baeldung/hashing/DigestAlgorithms.java

@@ -0,0 +1,9 @@
+package com.baeldung.hashing;
+
+public class DigestAlgorithms {
+
+    public static final String SHA3_256 = "SHA3-256";
+    public static final String SHA_256 = "SHA-256";
+    public static final String KECCAK_256 = "Keccak-256";
+
+}

core-java-security/src/main/java/com/baeldung/hashing/Keccak256Hashing.java

@@ -0,0 +1,30 @@
+package com.baeldung.hashing;
+
+import org.bouncycastle.jcajce.provider.digest.Keccak;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.bouncycastle.util.encoders.Hex;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.Security;
+
+import static com.baeldung.hashing.DigestAlgorithms.KECCAK_256;
+import static com.baeldung.hashing.SHACommonUtils.bytesToHex;
+
+public class Keccak256Hashing {
+
+    public static String hashWithJavaMessageDigest(final String originalString) throws NoSuchAlgorithmException {
+        Security.addProvider(new BouncyCastleProvider());
+        final MessageDigest digest = MessageDigest.getInstance(KECCAK_256);
+        final byte[] encodedhash = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
+        return bytesToHex(encodedhash);
+    }
+
+    public static String hashWithBouncyCastle(final String originalString) {
+        Keccak.Digest256 digest256 = new Keccak.Digest256();
+        byte[] hashbytes = digest256.digest(originalString.getBytes(StandardCharsets.UTF_8));
+        return new String(Hex.encode(hashbytes));
+    }
+
+}

core-java-security/src/main/java/com/baeldung/hashing/SHA256Hashing.java

@@ -8,15 +8,18 @@ import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
+import static com.baeldung.hashing.DigestAlgorithms.SHA_256;
+import static com.baeldung.hashing.SHACommonUtils.bytesToHex;
+
 public class SHA256Hashing {
 
     public static String HashWithJavaMessageDigest(final String originalString) throws NoSuchAlgorithmException {
-        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        final MessageDigest digest = MessageDigest.getInstance(SHA_256);
         final byte[] encodedhash = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
         return bytesToHex(encodedhash);
     }
 
-    public static String HashWithGuava(final String originalString) {
+    public static String hashWithGuava(final String originalString) {
         final String sha256hex = Hashing.sha256().hashString(originalString, StandardCharsets.UTF_8).toString();
         return sha256hex;
     }
@@ -27,20 +30,10 @@ public class SHA256Hashing {
     }
 
     public static String HashWithBouncyCastle(final String originalString) throws NoSuchAlgorithmException {
-        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        final MessageDigest digest = MessageDigest.getInstance(SHA_256);
         final byte[] hash = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
         final String sha256hex = new String(Hex.encode(hash));
         return sha256hex;
     }
 
-    private static String bytesToHex(byte[] hash) {
-        StringBuffer hexString = new StringBuffer();
-        for (int i = 0; i < hash.length; i++) {
-            String hex = Integer.toHexString(0xff & hash[i]);
-            if (hex.length() == 1)
-                hexString.append('0');
-            hexString.append(hex);
-        }
-        return hexString.toString();
-    }
 }

core-java-security/src/main/java/com/baeldung/hashing/SHA3Hashing.java

@@ -0,0 +1,45 @@
+package com.baeldung.hashing;
+
+import com.google.common.hash.Hashing;
+import org.apache.commons.codec.digest.DigestUtils;
+import org.bouncycastle.crypto.digests.SHA3Digest;
+import org.bouncycastle.jcajce.provider.digest.SHA3;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.bouncycastle.util.encoders.Hex;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.Security;
+
+import static com.baeldung.hashing.DigestAlgorithms.SHA3_256;
+import static com.baeldung.hashing.SHACommonUtils.bytesToHex;
+
+public class SHA3Hashing {
+
+    /* works with JDK9+ only */
+    public static String hashWithJavaMessageDigestJDK9(final String originalString) throws NoSuchAlgorithmException {
+        final MessageDigest digest = MessageDigest.getInstance(SHA3_256);
+        final byte[] hashbytes = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
+        return bytesToHex(hashbytes);
+    }
+
+    public static String hashWithJavaMessageDigest(final String originalString) throws NoSuchAlgorithmException {
+        Security.addProvider(new BouncyCastleProvider());
+        final MessageDigest digest = MessageDigest.getInstance(SHA3_256);
+        final byte[] hashbytes = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
+        return bytesToHex(hashbytes);
+    }
+
+    /* works with JDK9+ only */
+    public static String hashWithApacheCommonsJDK9(final String originalString) {
+        return new DigestUtils(SHA3_256).digestAsHex(originalString);
+    }
+
+    public static String hashWithBouncyCastle(final String originalString) {
+        SHA3.Digest256 digest256 = new SHA3.Digest256();
+        byte[] hashbytes = digest256.digest(originalString.getBytes(StandardCharsets.UTF_8));
+        return new String(Hex.encode(hashbytes));
+    }
+
+}

core-java-security/src/main/java/com/baeldung/hashing/SHACommonUtils.java

@@ -0,0 +1,16 @@
+package com.baeldung.hashing;
+
+class SHACommonUtils {
+
+    public static String bytesToHex(byte[] hash) {
+        StringBuffer hexString = new StringBuffer();
+        for (byte h : hash) {
+            String hex = Integer.toHexString(0xff & h);
+            if (hex.length() == 1)
+                hexString.append('0');
+            hexString.append(hex);
+        }
+        return hexString.toString();
+    }
+
+}

core-java-security/src/test/java/com/baeldung/hashing/Keccak256HashingUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.hashing;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class Keccak256HashingUnitTest {
+
+    private static String originalValue = "abc123";
+    private static String hashedValue = "719accc61a9cc126830e5906f9d672d06eab6f8597287095a2c55a8b775e7016";
+
+    @Test public void testHashWithJavaMessageDigest() throws Exception {
+        final String currentHashedValue = Keccak256Hashing.hashWithJavaMessageDigest(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
+    }
+
+    @Test public void testHashWithBouncyCastle() {
+        final String currentHashedValue = Keccak256Hashing.hashWithBouncyCastle(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
+    }
+
+}

core-java-security/src/test/java/com/baeldung/hashing/SHA256HashingUnitTest.java

@@ -12,24 +12,24 @@ public class SHA256HashingUnitTest {
     @Test
     public void testHashWithJavaMessageDigest() throws Exception {
         final String currentHashedValue = SHA256Hashing.HashWithJavaMessageDigest(originalValue);
-        assertEquals(currentHashedValue, hashedValue);
+        assertEquals(hashedValue, currentHashedValue);
     }
 
     @Test
     public void testHashWithGuava() throws Exception {
-        final String currentHashedValue = SHA256Hashing.HashWithApacheCommons(originalValue);
-        assertEquals(currentHashedValue, hashedValue);
+        final String currentHashedValue = SHA256Hashing.hashWithGuava(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
     }
 
     @Test
     public void testHashWithApacheCommans() throws Exception {
-        final String currentHashedValue = SHA256Hashing.HashWithGuava(originalValue);
-        assertEquals(currentHashedValue, hashedValue);
+        final String currentHashedValue = SHA256Hashing.HashWithApacheCommons(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
     }
 
     @Test
     public void testHashWithBouncyCastle() throws Exception {
         final String currentHashedValue = SHA256Hashing.HashWithBouncyCastle(originalValue);
-        assertEquals(currentHashedValue, hashedValue);
+        assertEquals(hashedValue, currentHashedValue);
     }
 }

core-java-security/src/test/java/com/baeldung/hashing/SHA3HashingUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.hashing;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class SHA3HashingUnitTest {
+
+    private static String originalValue = "abc123";
+    private static String hashedValue = "f58fa3df820114f56e1544354379820cff464c9c41cb3ca0ad0b0843c9bb67ee";
+
+    /* works with JDK9+ only */
+    //@Test
+    public void testHashWithJavaMessageDigestJDK9() throws Exception {
+        final String currentHashedValue = SHA3Hashing.hashWithJavaMessageDigestJDK9(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
+    }
+
+    @Test
+    public void testHashWithJavaMessageDigest() throws Exception {
+        final String currentHashedValue = SHA3Hashing.hashWithJavaMessageDigest(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
+    }
+
+    /* works with JDK9+ only */
+    //@Test
+    public void testHashWithApacheCommonsJDK9() {
+        final String currentHashedValue = SHA3Hashing.hashWithApacheCommonsJDK9(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
+    }
+
+    @Test
+    public void testHashWithBouncyCastle() {
+        final String currentHashedValue = SHA3Hashing.hashWithBouncyCastle(originalValue);
+        assertEquals(hashedValue, currentHashedValue);
+    }
+
+}

core-java/README.md

@@ -46,3 +46,8 @@
 - [Graphs in Java](https://www.baeldung.com/java-graphs)
 - [Console I/O in Java](http://www.baeldung.com/java-console-input-output)
 - [Formatting with printf() in Java](https://www.baeldung.com/java-printstream-printf)
+- [Retrieve Fields from a Java Class Using Reflection](https://www.baeldung.com/java-reflection-class-fields)
+- [Introduction to Basic Syntax in Java](https://www.baeldung.com/java-syntax)
+- [Using Curl in Java](https://www.baeldung.com/java-curl)
+- [Finding Leap Years in Java](https://www.baeldung.com/java-leap-year)
+- [Java Bitwise Operators](https://www.baeldung.com/java-bitwise-operators)

core-java/src/main/java/com/baeldung/jar/JarExample.java

@@ -0,0 +1,9 @@
+package com.baeldung.jar;
+
+public class JarExample {
+
+    public static void main(String[] args) {
+        System.out.println("Hello Baeldung Reader!");
+    }
+
+}

core-java/src/main/java/com/baeldung/jar/example_manifest.txt

@@ -0,0 +1 @@
+Main-Class: com.baeldung.jar.JarExample

core-kotlin/README.md

@@ -51,3 +51,4 @@
 - [Operator Overloading in Kotlin](https://www.baeldung.com/kotlin-operator-overloading)
 - [Inline Classes in Kotlin](https://www.baeldung.com/kotlin-inline-classes)
 - [Creating Java static final Equivalents in Kotlin](https://www.baeldung.com/kotlin-java-static-final)
+- [Nested forEach in Kotlin](https://www.baeldung.com/kotlin-nested-foreach)

guice/pom.xml

@@ -26,4 +26,4 @@
         <guice.version>4.1.0</guice.version>
     </properties>
 
-</project>
+</project>

guice/src/main/java/com/baeldung/examples/common/Account.java

@@ -0,0 +1,24 @@
+package com.baeldung.examples.common;
+
+public class Account {
+
+	private String accountNumber;
+	private String type;
+
+	public String getAccountNumber() {
+		return accountNumber;
+	}
+
+	public void setAccountNumber(String accountNumber) {
+		this.accountNumber = accountNumber;
+	}
+
+	public String getType() {
+		return type;
+	}
+
+	public void setType(String type) {
+		this.type = type;
+	}
+
+}

guice/src/main/java/com/baeldung/examples/common/AccountService.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public interface AccountService {
+
+}

guice/src/main/java/com/baeldung/examples/common/AccountServiceImpl.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public class AccountServiceImpl implements AccountService {
+
+}

guice/src/main/java/com/baeldung/examples/common/AudioBookService.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public interface AudioBookService {
+
+}

guice/src/main/java/com/baeldung/examples/common/AudioBookServiceImpl.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public class AudioBookServiceImpl implements AudioBookService {
+
+}

guice/src/main/java/com/baeldung/examples/common/AuthorService.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public interface AuthorService {
+
+}

guice/src/main/java/com/baeldung/examples/common/AuthorServiceImpl.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public class AuthorServiceImpl implements AuthorService {
+
+}

guice/src/main/java/com/baeldung/examples/common/BookService.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public interface BookService {
+
+}

guice/src/main/java/com/baeldung/examples/common/BookServiceImpl.java

@@ -0,0 +1,7 @@
+package com.baeldung.examples.common;
+
+public class BookServiceImpl implements BookService {
+
+	private AuthorService authorService;
+
+}

guice/src/main/java/com/baeldung/examples/common/PersonDao.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public interface PersonDao {
+
+}

guice/src/main/java/com/baeldung/examples/common/PersonDaoImpl.java

@@ -0,0 +1,5 @@
+package com.baeldung.examples.common;
+
+public class PersonDaoImpl implements PersonDao {
+
+}

guice/src/main/java/com/baeldung/examples/guice/Foo.java

@@ -0,0 +1,4 @@
+package com.baeldung.examples.guice;
+
+public class Foo {
+}

guice/src/main/java/com/baeldung/examples/guice/FooProcessor.java

@@ -0,0 +1,9 @@
+package com.baeldung.examples.guice;
+
+import com.google.inject.Inject;
+
+public class FooProcessor {
+
+	@Inject
+	private Foo foo;
+}

guice/src/main/java/com/baeldung/examples/guice/GuicePersonService.java

@@ -0,0 +1,19 @@
+package com.baeldung.examples.guice;
+
+import com.baeldung.examples.common.PersonDao;
+import com.google.inject.Inject;
+
+public class GuicePersonService {
+
+	@Inject
+	private PersonDao personDao;
+
+	public PersonDao getPersonDao() {
+		return personDao;
+	}
+
+	public void setPersonDao(PersonDao personDao) {
+		this.personDao = personDao;
+	}
+
+}

guice/src/main/java/com/baeldung/examples/guice/GuiceUserService.java

@@ -0,0 +1,19 @@
+package com.baeldung.examples.guice;
+
+import com.baeldung.examples.common.AccountService;
+import com.google.inject.Inject;
+
+public class GuiceUserService {
+
+	@Inject
+	private AccountService accountService;
+
+	public AccountService getAccountService() {
+		return accountService;
+	}
+
+	public void setAccountService(AccountService accountService) {
+		this.accountService = accountService;
+	}
+
+}

guice/src/main/java/com/baeldung/examples/guice/Person.java

@@ -0,0 +1,24 @@
+package com.baeldung.examples.guice;
+
+public class Person {
+	private String firstName;
+
+	private String lastName;
+
+	public String getFirstName() {
+		return firstName;
+	}
+
+	public void setFirstName(String firstName) {
+		this.firstName = firstName;
+	}
+
+	public String getLastName() {
+		return lastName;
+	}
+
+	public void setLastName(String lastName) {
+		this.lastName = lastName;
+	}
+
+}

guice/src/main/java/com/baeldung/examples/guice/modules/GuiceModule.java

@@ -0,0 +1,50 @@
+package com.baeldung.examples.guice.modules;
+
+import com.baeldung.examples.common.AccountService;
+import com.baeldung.examples.common.AccountServiceImpl;
+import com.baeldung.examples.common.BookService;
+import com.baeldung.examples.common.BookServiceImpl;
+import com.baeldung.examples.common.PersonDao;
+import com.baeldung.examples.common.PersonDaoImpl;
+import com.baeldung.examples.guice.Foo;
+import com.baeldung.examples.guice.Person;
+import com.google.inject.AbstractModule;
+import com.google.inject.Provider;
+import com.google.inject.Provides;
+
+public class GuiceModule extends AbstractModule {
+
+	@Override
+	protected void configure() {
+		try {
+			bind(AccountService.class).to(AccountServiceImpl.class);
+			bind(Person.class).toConstructor(Person.class.getConstructor());
+			// bind(Person.class).toProvider(new Provider<Person>() {
+			// public Person get() {
+			// Person p = new Person();
+			// return p;
+			// }
+			// });
+			bind(Foo.class).toProvider(new Provider<Foo>() {
+				public Foo get() {
+					return new Foo();
+				}
+			});
+			bind(PersonDao.class).to(PersonDaoImpl.class);
+
+		} catch (NoSuchMethodException e) {
+			// TODO Auto-generated catch block
+			e.printStackTrace();
+		} catch (SecurityException e) {
+			// TODO Auto-generated catch block
+			e.printStackTrace();
+		}
+
+	}
+
+	@Provides
+	public BookService bookServiceGenerator() {
+		return new BookServiceImpl();
+	}
+
+}

guice/src/test/java/com/baeldung/examples/GuiceUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.examples;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.Test;
+
+import com.baeldung.examples.common.BookService;
+import com.baeldung.examples.guice.FooProcessor;
+import com.baeldung.examples.guice.GuicePersonService;
+import com.baeldung.examples.guice.GuiceUserService;
+import com.baeldung.examples.guice.Person;
+import com.baeldung.examples.guice.modules.GuiceModule;
+import com.google.inject.Guice;
+import com.google.inject.Injector;
+
+public class GuiceUnitTest {
+
+	@Test
+	public void givenAccountServiceInjectedInGuiceUserService_WhenGetAccountServiceInvoked_ThenReturnValueIsNotNull() {
+		Injector injector = Guice.createInjector(new GuiceModule());
+		GuiceUserService guiceUserService = injector.getInstance(GuiceUserService.class);
+		assertNotNull(guiceUserService.getAccountService());
+	}
+
+	@Test
+	public void givenBookServiceIsRegisteredInModule_WhenBookServiceIsInjected_ThenReturnValueIsNotNull() {
+		Injector injector = Guice.createInjector(new GuiceModule());
+		BookService bookService = injector.getInstance(BookService.class);
+		assertNotNull(bookService);
+	}
+
+	@Test
+	public void givenMultipleBindingsForPerson_WhenPersonIsInjected_ThenTestFailsByProvisionException() {
+		Injector injector = Guice.createInjector(new GuiceModule());
+		Person person = injector.getInstance(Person.class);
+		assertNotNull(person);
+	}
+
+	@Test
+	public void givenFooInjectedToFooProcessorAsOptionalDependency_WhenFooProcessorIsRetrievedFromContext_ThenCreationExceptionIsNotThrown() {
+		Injector injector = Guice.createInjector(new GuiceModule());
+		FooProcessor fooProcessor = injector.getInstance(FooProcessor.class);
+		assertNotNull(fooProcessor);
+	}
+
+	@Test
+	public void givenGuicePersonServiceConstructorAnnotatedByInject_WhenGuicePersonServiceIsInjected_ThenInstanceWillBeCreatedFromTheConstructor() {
+		Injector injector = Guice.createInjector(new GuiceModule());
+		GuicePersonService personService = injector.getInstance(GuicePersonService.class);
+		assertNotNull(personService);
+	}
+
+	@Test
+	public void givenPersonDaoInjectedToGuicePersonServiceBySetterInjection_WhenGuicePersonServiceIsInjected_ThenPersonDaoInitializedByTheSetter() {
+		Injector injector = Guice.createInjector(new GuiceModule());
+		GuicePersonService personService = injector.getInstance(GuicePersonService.class);
+		assertNotNull(personService);
+		assertNotNull(personService.getPersonDao());
+	}
+
+}

jackson/README.md

@@ -37,3 +37,4 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 - [Serialize Only Fields that meet a Custom Criteria with Jackson](http://www.baeldung.com/jackson-serialize-field-custom-criteria)
 - [Mapping Nested Values with Jackson](http://www.baeldung.com/jackson-nested-values)
 - [Convert XML to JSON Using Jackson](https://www.baeldung.com/jackson-convert-xml-json)
+- [Deserialize Immutable Objects with Jackson](https://www.baeldung.com/jackson-deserialize-immutable-objects)

java-collections-maps/README.md

@@ -19,3 +19,4 @@
 - [How to Check If a Key Exists in a Map](https://www.baeldung.com/java-map-key-exists)
 - [Comparing Two HashMaps in Java](https://www.baeldung.com/java-compare-hashmaps)
 - [Immutable Map Implementations in Java](https://www.baeldung.com/java-immutable-maps) 
+- [Map to String Conversion in Java](https://www.baeldung.com/java-map-to-string-conversion)

java-dates/README.md

@@ -27,4 +27,5 @@
 - [Convert Between java.time.Instant and java.sql.Timestamp](https://www.baeldung.com/java-time-instant-to-java-sql-timestamp)
 - [Convert between String and Timestamp](https://www.baeldung.com/java-string-to-timestamp)
 - [A Guide to SimpleDateFormat](https://www.baeldung.com/java-simple-date-format)
-- [ZoneOffset in Java](https://www.baeldung.com/java-zone-offset)
+- [ZoneOffset in Java](https://www.baeldung.com/java-zone-offset)
+- [Differences Between ZonedDateTime and OffsetDateTime](https://www.baeldung.com/java-zoneddatetime-offsetdatetime)

java-streams/README.md

@@ -15,3 +15,5 @@
 - [Stream Ordering in Java](https://www.baeldung.com/java-stream-ordering)
 - [Introduction to Protonpack](https://www.baeldung.com/java-protonpack)
 - [Java Stream Filter with Lambda Expression](https://www.baeldung.com/java-stream-filter-lambda)
+- [Counting Matches on a Stream Filter](https://www.baeldung.com/java-stream-filter-count)
+- [Java 8 Streams peek() API](https://www.baeldung.com/java-streams-peek-api)

java-strings/README.md

@@ -50,3 +50,6 @@
 - [Remove Leading and Trailing Characters from a String](https://www.baeldung.com/java-remove-trailing-characters)
 - [Concatenating Strings In Java](https://www.baeldung.com/java-strings-concatenation)
 - [Java toString() Method](https://www.baeldung.com/java-tostring)
+- [Java String Interview Questions and Answers](https://www.baeldung.com/java-string-interview-questions)
+- [Check if a String is a Pangram in Java](https://www.baeldung.com/java-string-pangram)
+- [Check If a String Contains Multiple Keywords](https://www.baeldung.com/string-contains-multiple-words)

jooby/src/test/java/com/baeldung/jooby/AppLiveTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.jooby;
+
+import static io.restassured.RestAssured.get;
+import static org.hamcrest.Matchers.equalTo;
+
+import org.jooby.test.JoobyRule;
+import org.junit.ClassRule;
+import org.junit.Test;
+
+public class AppLiveTest {
+
+	@ClassRule
+	public static JoobyRule app = new JoobyRule(new App());
+
+	@Test
+	public void given_defaultUrl_expect_fixedString() {
+		get("/").then().assertThat().body(equalTo("Hello World!")).statusCode(200)
+				.contentType("text/html;charset=UTF-8");
+	}
+
+}

jooby/src/test/java/com/baeldung/jooby/AppUnitTest.java

@@ -1,25 +1,12 @@
 package com.baeldung.jooby;
 
-import static io.restassured.RestAssured.get;
-import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertEquals;
 
-import org.jooby.test.JoobyRule;
 import org.jooby.test.MockRouter;
-import org.junit.ClassRule;
 import org.junit.Test;
 
 public class AppUnitTest {
 
-	@ClassRule
-	public static JoobyRule app = new JoobyRule(new App());
-
-	@Test
-	public void given_defaultUrl_expect_fixedString() {
-		get("/").then().assertThat().body(equalTo("Hello World!")).statusCode(200)
-				.contentType("text/html;charset=UTF-8");
-	}
-
 	@Test
 	public void given_defaultUrl_with_mockrouter_expect_fixedString() throws Throwable {
 		String result = new MockRouter(new App()).get("/");

kotlin-libraries/README.md

@@ -9,3 +9,4 @@
 - [Working with Dates in Kotlin](https://www.baeldung.com/kotlin-dates)
 - [Introduction to Arrow in Kotlin](https://www.baeldung.com/kotlin-arrow)
 - [Kotlin with Ktor](https://www.baeldung.com/kotlin-ktor)
+- [REST API With Kotlin and Kovert](https://www.baeldung.com/kotlin-kovert)

libraries-server/README.md

@@ -7,3 +7,4 @@
 - [Creating and Configuring Jetty 9 Server in Java](http://www.baeldung.com/jetty-java-programmatic)
 - [Testing Netty with EmbeddedChannel](http://www.baeldung.com/testing-netty-embedded-channel)
 - [MQTT Client in Java](https://www.baeldung.com/java-mqtt-client)
+- [Guide to XMPP Smack Client](https://www.baeldung.com/xmpp-smack-chat-client)

libraries/README.md

@@ -64,7 +64,8 @@
 - [Exactly Once Processing in Kafka](https://www.baeldung.com/kafka-exactly-once)
 - [An Introduction to SuanShu](https://www.baeldung.com/suanshu)
 - [Implementing a FTP-Client in Java](http://www.baeldung.com/java-ftp-client)
-- [Introduction to Functional Java](https://www.baeldung.com/java-functional-library
+- [Introduction to Functional Java](https://www.baeldung.com/java-functional-library)
+- [Intro to Derive4J](https://www.baeldung.com/derive4j)
 
 The libraries module contains examples related to small libraries that are relatively easy to use and does not require any separate module of its own.
 

mapstruct/pom.xml

@@ -30,6 +30,11 @@
             <version>${springframework.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${org.projectlombok.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -48,6 +53,11 @@
                             <artifactId>mapstruct-processor</artifactId>
                             <version>${org.mapstruct.version}</version>
                         </path>
+                        <path>
+                            <groupId>org.projectlombok</groupId>
+                            <artifactId>lombok</artifactId>
+                            <version>${org.projectlombok.version}</version>
+                        </path>
                     </annotationProcessorPaths>
                 </configuration>
             </plugin>
@@ -55,10 +65,11 @@
     </build>
 
     <properties>
-        <org.mapstruct.version>1.1.0.Final</org.mapstruct.version>
+        <org.mapstruct.version>1.3.0.Beta2</org.mapstruct.version>
         <springframework.version>4.3.4.RELEASE</springframework.version>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
+        <org.projectlombok.version>1.18.4</org.projectlombok.version>
     </properties>
 
 </project> 

mapstruct/src/main/java/com/baeldung/dto/CarDTO.java

@@ -0,0 +1,11 @@
+package com.baeldung.dto;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class CarDTO {
+    private int id;
+    private String name;
+}

mapstruct/src/main/java/com/baeldung/dto/PersonDTO.java

@@ -0,0 +1,33 @@
+package com.baeldung.dto;
+
+public class PersonDTO {
+    
+    private String id;
+    private String name;
+
+    public PersonDTO() {
+
+    }
+
+    public PersonDTO(String id, String name) {
+        super();
+        this.id = id;
+        this.name = name;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

mapstruct/src/main/java/com/baeldung/entity/Car.java

@@ -0,0 +1,11 @@
+package com.baeldung.entity;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class Car {
+    private int id;
+    private String name;
+}

mapstruct/src/main/java/com/baeldung/entity/Person.java

@@ -0,0 +1,33 @@
+package com.baeldung.entity;
+
+public class Person {
+    
+    private String id;
+    private String name;
+    
+    public Person() {
+        
+    }
+    
+    public Person(String id, String name) {
+        super();
+        this.id = id;
+        this.name = name;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

mapstruct/src/main/java/com/baeldung/mapper/CarMapper.java

@@ -0,0 +1,15 @@
+package com.baeldung.mapper;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+import com.baeldung.dto.CarDTO;
+import com.baeldung.entity.Car;
+
+@Mapper
+public interface CarMapper {
+    
+    CarMapper INSTANCE = Mappers.getMapper(CarMapper.class);
+    
+    CarDTO carToCarDTO(Car car);
+}

mapstruct/src/main/java/com/baeldung/mapper/PersonMapper.java

@@ -0,0 +1,17 @@
+package com.baeldung.mapper;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+import com.baeldung.dto.PersonDTO;
+import com.baeldung.entity.Person;
+
+@Mapper
+public interface PersonMapper {
+    
+    PersonMapper INSTANCE = Mappers.getMapper(PersonMapper.class);
+    
+    @Mapping(target = "id", source = "person.id", defaultExpression = "java(java.util.UUID.randomUUID().toString())")
+    PersonDTO personToPersonDTO(Person person);
+}

mapstruct/src/test/java/com/baeldung/mapper/CarMapperUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.mapper;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import com.baeldung.dto.CarDTO;
+import com.baeldung.entity.Car;
+
+public class CarMapperUnitTest {
+
+    @Test
+    public void givenCarEntitytoCar_whenMaps_thenCorrect() {
+        
+        Car entity  = new Car();
+        entity.setId(1);
+        entity.setName("Toyota");
+        
+        CarDTO carDto = CarMapper.INSTANCE.carToCarDTO(entity);
+
+        assertEquals(carDto.getId(), entity.getId());
+        assertEquals(carDto.getName(), entity.getName());
+    }
+}

mapstruct/src/test/java/com/baeldung/mapper/PersonMapperUnitTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.mapper;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import org.junit.Test;
+
+import com.baeldung.dto.PersonDTO;
+import com.baeldung.entity.Person;
+
+public class PersonMapperUnitTest {
+
+    @Test
+    public void givenPersonEntitytoPersonWithExpression_whenMaps_thenCorrect() {
+        
+        Person entity  = new Person();
+        entity.setName("Micheal");
+        
+        PersonDTO personDto = PersonMapper.INSTANCE.personToPersonDTO(entity);
+
+        assertNull(entity.getId());
+        assertNotNull(personDto.getId());
+        assertEquals(personDto.getName(), entity.getName());
+    }
+}

persistence-modules/hibernate5/README.md

@@ -29,3 +29,4 @@
 - [Hibernate Named Query](https://www.baeldung.com/hibernate-named-query)
 - [Using c3p0 with Hibernate](https://www.baeldung.com/hibernate-c3p0)
 - [Persist a JSON Object Using Hibernate](https://www.baeldung.com/hibernate-persist-json-object)
+- [Common Hibernate Exceptions](https://www.baeldung.com/hibernate-exceptions)

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/pojo/Student.java

@@ -9,15 +9,43 @@ import javax.persistence.Id;
 public class Student {
 
     @Id
-    @GeneratedValue (strategy = GenerationType.SEQUENCE)
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
     private long studentId;
 
+    private String name;
+
+    private int age;
+
+    public Student() {
+    }
+
+    public Student(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
     public long getStudentId() {
         return studentId;
     }
 
-    public void setStudent_id(long studentId) {
+    public void setStudentId(long studentId) {
         this.studentId = studentId;
     }
-    
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
 }

persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/aggregatefunctions/AggregateFunctionsIntegrationTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.hibernate.aggregatefunctions;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.IOException;
+
+import org.hibernate.HibernateException;
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import com.baeldung.hibernate.HibernateUtil;
+import com.baeldung.hibernate.pojo.Student;
+
+public class AggregateFunctionsIntegrationTest {
+
+    private static Session session;
+    private static Transaction transaction;
+
+    @BeforeClass
+    public static final void setup() throws HibernateException, IOException {
+        session = HibernateUtil.getSessionFactory()
+            .openSession();
+        transaction = session.beginTransaction();
+
+        Student jonas = new Student("Jonas", 22);
+        session.save(jonas);
+
+        Student sally = new Student("Sally", 20);
+        session.save(sally);
+
+        Student simon = new Student("Simon", 25);
+        session.save(simon);
+
+        Student raven = new Student("Raven", 21);
+        session.save(raven);
+
+        Student sam = new Student("Sam", 23);
+        session.save(sam);
+
+    }
+
+    @AfterClass
+    public static final void teardown() {
+        if (session != null) {
+            transaction.rollback();
+            session.close();
+        }
+    }
+
+    @Test
+    public void whenMaxAge_ThenReturnValue() {
+        int maxAge = (int) session.createQuery("SELECT MAX(age) from Student")
+            .getSingleResult();
+        assertThat(maxAge).isEqualTo(25);
+    }
+
+    @Test
+    public void whenMinAge_ThenReturnValue() {
+        int minAge = (int) session.createQuery("SELECT MIN(age) from Student")
+            .getSingleResult();
+        assertThat(minAge).isEqualTo(20);
+    }
+
+    @Test
+    public void whenAverageAge_ThenReturnValue() {
+        Double avgAge = (Double) session.createQuery("SELECT AVG(age) from Student")
+            .getSingleResult();
+        assertThat(avgAge).isEqualTo(22.2);
+    }
+
+    @Test
+    public void whenCountAll_ThenReturnValue() {
+        Long totalStudents = (Long) session.createQuery("SELECT COUNT(*) from Student")
+            .getSingleResult();
+        assertThat(totalStudents).isEqualTo(5);
+    }
+
+    @Test
+    public void whenSumOfAllAges_ThenReturnValue() {
+        Long sumOfAllAges = (Long) session.createQuery("SELECT SUM(age) from Student")
+            .getSingleResult();
+        assertThat(sumOfAllAges).isEqualTo(111);
+    }
+}

persistence-modules/java-jpa/README.md

@@ -4,3 +4,5 @@
 - [A Guide to Stored Procedures with JPA](http://www.baeldung.com/jpa-stored-procedures)
 - [Fixing the JPA error “java.lang.String cannot be cast to Ljava.lang.String;”](https://www.baeldung.com/jpa-error-java-lang-string-cannot-be-cast) 
 - [JPA Entity Graph](https://www.baeldung.com/jpa-entity-graph)
+- [JPA 2.2 Support for Java 8 Date/Time Types](https://www.baeldung.com/jpa-java-time)
+- [Converting Between LocalDate and SQL Date](https://www.baeldung.com/java-convert-localdate-sql-date)

persistence-modules/spring-boot-h2/spring-boot-h2-database/src/test/java/com/baeldung/SpringContextIntegrationTest.java

@@ -0,0 +1,19 @@
+package com.baeldung;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.support.AnnotationConfigContextLoader;
+import org.springframework.test.context.web.WebAppConfiguration;
+
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(loader = AnnotationConfigContextLoader.class)
+@WebAppConfiguration
+public class SpringContextIntegrationTest {
+
+    @Test
+    public void whenSpringContextIsBootstrapped_thenNoExceptions() {
+    }
+}

persistence-modules/spring-boot-persistence/README.MD

@@ -6,4 +6,4 @@
 - [Configuring a Tomcat Connection Pool in Spring Boot](https://www.baeldung.com/spring-boot-tomcat-connection-pool)
 - [Hibernate Field Naming with Spring Boot](https://www.baeldung.com/hibernate-field-naming-spring-boot)
 - [Integrating Spring Boot with HSQLDB](https://www.baeldung.com/spring-boot-hsqldb)
-
+- [Configuring a DataSource Programmatically in Spring Boot](https://www.baeldung.com/spring-boot-configure-data-source-programmatic)

persistence-modules/spring-data-jpa/README.md

@@ -19,6 +19,7 @@
 - [Sorting Query Results with Spring Data](https://www.baeldung.com/spring-data-sorting)
 - [INSERT Statement in JPA](https://www.baeldung.com/jpa-insert)
 - [Pagination and Sorting using Spring Data JPA](https://www.baeldung.com/spring-data-jpa-pagination-sorting)
+- [Spring Data JPA Query by Example](https://www.baeldung.com/spring-data-query-by-example)
 
 ### Eclipse Config 
 After importing the project into Eclipse, you may see the following error:  

persistence-modules/spring-hibernate-5/src/test/java/com/baeldung/hibernate/criteria/HibernateCriteriaIntegrationTest.java

@@ -1,17 +1,24 @@
 package com.baeldung.hibernate.criteria;
 
 import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 import java.util.List;
 
 import org.hibernate.Session;
+import org.hibernate.Transaction;
 import org.junit.Test;
 
 import com.baeldung.hibernate.criteria.model.Item;
 import com.baeldung.hibernate.criteria.util.HibernateUtil;
 import com.baeldung.hibernate.criteria.view.ApplicationView;
 
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaDelete;
+import javax.persistence.criteria.CriteriaUpdate;
+import javax.persistence.criteria.Root;
+
 public class HibernateCriteriaIntegrationTest {
 
     final private ApplicationView av = new ApplicationView();
@@ -179,4 +186,51 @@ public class HibernateCriteriaIntegrationTest {
         session.close();
         assertArrayEquals(expectedPriceBetweenItems, av.betweenCriteria());
     }
+
+    @Test
+    public void givenNewItemPrice_whenCriteriaUpdate_thenReturnAffectedResult() {
+
+        int oldPrice = 10, newPrice = 20;
+
+        Session session = HibernateUtil.getHibernateSession();
+
+        Item item = new Item(12, "Test Item 12", "This is a description");
+        item.setItemPrice(oldPrice);
+        session.save(item);
+
+        CriteriaBuilder cb = session.getCriteriaBuilder();
+        CriteriaUpdate<Item> criteriaUpdate = cb.createCriteriaUpdate(Item.class);
+        Root<Item> root = criteriaUpdate.from(Item.class);
+        criteriaUpdate.set("itemPrice", newPrice);
+        criteriaUpdate.where(cb.equal(root.get("itemPrice"), oldPrice));
+
+        Transaction transaction = session.beginTransaction();
+        session.createQuery(criteriaUpdate).executeUpdate();
+        transaction.commit();
+
+        Item updatedItem = session.createQuery("FROM Item WHERE itemPrice = " + newPrice, Item.class).getSingleResult();
+        session.refresh(updatedItem);
+        assertEquals(newPrice, updatedItem.getItemPrice().intValue());
+    }
+
+    @Test
+    public void givenTargetItemPrice_whenCriteriaDelete_thenDeleteMatched() {
+
+        int targetPrice = 1000;
+
+        Session session = HibernateUtil.getHibernateSession();
+        CriteriaBuilder cb = session.getCriteriaBuilder();
+        CriteriaDelete<Item> criteriaDelete = cb.createCriteriaDelete(Item.class);
+        Root<Item> root = criteriaDelete.from(Item.class);
+        criteriaDelete.where(cb.greaterThan(root.get("itemPrice"), targetPrice));
+
+        Transaction transaction = session.beginTransaction();
+        session.createQuery(criteriaDelete).executeUpdate();
+        transaction.commit();
+
+        List<Item> deletedItem = session.createQuery("FROM Item WHERE itemPrice > " + targetPrice, Item.class).list();
+        assertTrue(deletedItem.isEmpty());
+
+    }
+
 }

persistence-modules/spring-jpa/src/test/java/com/baeldung/SpringContextIntegrationTest.java

@@ -0,0 +1,19 @@
+package com.baeldung;
+
+import org.baeldung.config.PersistenceJPAConfigL2Cache;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.support.AnnotationConfigContextLoader;
+import org.springframework.test.context.web.WebAppConfiguration;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { PersistenceJPAConfigL2Cache.class }, loader = AnnotationConfigContextLoader.class)
+@WebAppConfiguration
+public class SpringContextIntegrationTest {
+
+    @Test
+    public void whenSpringContextIsBootstrapped_thenNoExceptions() {
+    }
+}

pom.xml

@@ -733,6 +733,7 @@
                 <module>spring-security-mvc-boot</module>
                 <module>spring-security-mvc-custom</module>
                 <module>spring-security-mvc-digest-auth</module>
+				<module>spring-security-mvc-jsonview</module>
                 <module>spring-security-mvc-ldap</module>
                 <module>spring-security-mvc-login</module>
                 <module>spring-security-mvc-persisted-remember-me</module>

spring-4/src/test/java/org/baeldung/SpringContextIntegrationTest.java

@@ -2,13 +2,16 @@ package org.baeldung;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
 
 import com.baeldung.flips.ApplicationConfig;
 
-@RunWith(SpringRunner.class)
-@SpringBootTest(classes = ApplicationConfig.class)
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = ApplicationConfig.class)
+@WebAppConfiguration
 public class SpringContextIntegrationTest {
 
     @Test

spring-5-reactive-oauth/README.md

@@ -1,3 +1,4 @@
 ### Relevant Articles: 
 
 - [Spring Security OAuth Login with WebFlux](https://www.baeldung.com/spring-oauth-login-webflux)
+- [Spring WebClient and OAuth2 Support](https://www.baeldung.com/spring-webclient-oauth2)

spring-5-reactive-oauth/pom.xml

@@ -62,11 +62,11 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-surefire-plugin</artifactId>
-				<version>2.20.1</version>
 				<configuration>
 					<testFailureIgnore>true</testFailureIgnore>
 					<excludes>
 						<exclude>**/*IntegrationTest.java</exclude>
+						<exclude>**/*LiveTest.java</exclude>
 					</excludes>
 				</configuration>
 			</plugin>

spring-boot-autoconfiguration/src/test/java/com/baeldung/SpringContextLiveTest.java

@@ -0,0 +1,19 @@
+package com.baeldung;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+
+import com.baeldung.autoconfiguration.MySQLAutoconfiguration;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = MySQLAutoconfiguration.class)
+@WebAppConfiguration
+public class SpringContextLiveTest {
+
+    @Test
+    public void whenSpringContextIsBootstrapped_thenNoExceptions() {
+    }
+}

spring-boot-bootstrap/README.md

@@ -5,3 +5,4 @@
 - [Deploying a Spring Boot Application to Cloud Foundry](https://www.baeldung.com/spring-boot-app-deploy-to-cloud-foundry)
 - [Deploy a Spring Boot Application to Google App Engine](https://www.baeldung.com/spring-boot-google-app-engine)
 - [Deploy a Spring Boot Application to OpenShift](https://www.baeldung.com/spring-boot-deploy-openshift)
+- [Deploy a Spring Boot Application to AWS Beanstalk](https://www.baeldung.com/spring-boot-deploy-aws-beanstalk)

spring-boot-mvc/README.md

@@ -9,4 +9,5 @@
 - [Display RSS Feed with Spring MVC](http://www.baeldung.com/spring-mvc-rss-feed)
 - [A Controller, Service and DAO Example with Spring Boot and JSF](https://www.baeldung.com/jsf-spring-boot-controller-service-dao)
 - [Cache Eviction in Spring Boot](https://www.baeldung.com/spring-boot-evict-cache)
-- [Setting Up Swagger 2 with a Spring REST API](http://www.baeldung.com/swagger-2-documentation-for-spring-rest-api)
+- [Setting Up Swagger 2 with a Spring REST API](http://www.baeldung.com/swagger-2-documentation-for-spring-rest-api)
+- [Conditionally Enable Scheduled Jobs in Spring](https://www.baeldung.com/spring-scheduled-enabled-conditionally)

spring-boot-rest/README.md

@@ -2,4 +2,5 @@ Module for the articles that are part of the Spring REST E-book:
 
 1. [Bootstrap a Web Application with Spring 5](https://www.baeldung.com/bootstraping-a-web-application-with-spring-and-java-based-configuration)
 2. [Error Handling for REST with Spring](http://www.baeldung.com/exception-handling-for-rest-with-spring)
-3. [REST Pagination in Spring](http://www.baeldung.com/rest-api-pagination-in-spring)
+3. [REST Pagination in Spring](http://www.baeldung.com/rest-api-pagination-in-spring)
+4. [Build a REST API with Spring and Java Config](http://www.baeldung.com/building-a-restful-web-service-with-spring-and-java-based-configuration)

spring-boot-rest/pom.xml

@@ -51,7 +51,6 @@
         <dependency>
             <groupId>net.sourceforge.htmlunit</groupId>
             <artifactId>htmlunit</artifactId>
-            <version>${htmlunit.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
@@ -67,7 +66,6 @@
 
     <properties>
         <start-class>com.baeldung.SpringBootRestApplication</start-class>
-        <htmlunit.version>2.32</htmlunit.version>
         <guava.version>27.0.1-jre</guava.version>
     </properties>
 </project>

spring-boot-rest/src/main/java/com/baeldung/persistence/IOperations.java

@@ -1,16 +1,29 @@
 package com.baeldung.persistence;
 
 import java.io.Serializable;
+import java.util.List;
 
 import org.springframework.data.domain.Page;
 
 public interface IOperations<T extends Serializable> {
 
+    // read - one
+
+    T findOne(final long id);
+
     // read - all
 
+    List<T> findAll();
+
     Page<T> findPaginated(int page, int size);
 
     // write
 
     T create(final T entity);
+
+    T update(final T entity);
+
+    void delete(final T entity);
+
+    void deleteById(final long entityId);
 }

spring-boot-rest/src/main/java/com/baeldung/persistence/service/common/AbstractService.java

@@ -1,6 +1,7 @@
 package com.baeldung.persistence.service.common;
 
 import java.io.Serializable;
+import java.util.List;
 
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageRequest;
@@ -8,23 +9,54 @@ import org.springframework.data.repository.PagingAndSortingRepository;
 import org.springframework.transaction.annotation.Transactional;
 
 import com.baeldung.persistence.IOperations;
+import com.google.common.collect.Lists;
 
 @Transactional
 public abstract class AbstractService<T extends Serializable> implements IOperations<T> {
 
+    // read - one
+
+    @Override
+    @Transactional(readOnly = true)
+    public T findOne(final long id) {
+        return getDao().findById(id)
+            .get();
+    }
+
     // read - all
 
+    @Override
+    @Transactional(readOnly = true)
+    public List<T> findAll() {
+        return Lists.newArrayList(getDao().findAll());
+    }
+
     @Override
     public Page<T> findPaginated(final int page, final int size) {
         return getDao().findAll(PageRequest.of(page, size));
     }
 
     // write
-
+    
     @Override
     public T create(final T entity) {
         return getDao().save(entity);
     }
+    
+    @Override
+    public T update(final T entity) {
+        return getDao().save(entity);
+    }
+
+    @Override
+    public void delete(final T entity) {
+        getDao().delete(entity);
+    }
+
+    @Override
+    public void deleteById(final long entityId) {
+        getDao().deleteById(entityId);
+    }
 
     protected abstract PagingAndSortingRepository<T, Long> getDao();
 

spring-boot-rest/src/main/java/com/baeldung/persistence/service/impl/FooService.java

@@ -1,5 +1,7 @@
 package com.baeldung.persistence.service.impl;
 
+import java.util.List;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
@@ -11,6 +13,7 @@ import com.baeldung.persistence.dao.IFooDao;
 import com.baeldung.persistence.model.Foo;
 import com.baeldung.persistence.service.IFooService;
 import com.baeldung.persistence.service.common.AbstractService;
+import com.google.common.collect.Lists;
 
 @Service
 @Transactional
@@ -36,5 +39,13 @@ public class FooService extends AbstractService<Foo> implements IFooService {
     public Page<Foo> findPaginated(Pageable pageable) {
         return dao.findAll(pageable);
     }
+    
+    // overridden to be secured
+
+    @Override
+    @Transactional(readOnly = true)
+    public List<Foo> findAll() {
+        return Lists.newArrayList(getDao().findAll());
+    }
 
 }

spring-boot-rest/src/main/java/com/baeldung/web/controller/FooController.java

@@ -9,14 +9,16 @@ import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.http.HttpStatus;
-import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
-import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RequestParam;
-import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.util.UriComponentsBuilder;
 
 import com.baeldung.persistence.model.Foo;
@@ -24,9 +26,11 @@ import com.baeldung.persistence.service.IFooService;
 import com.baeldung.web.exception.MyResourceNotFoundException;
 import com.baeldung.web.hateoas.event.PaginatedResultsRetrievedEvent;
 import com.baeldung.web.hateoas.event.ResourceCreatedEvent;
+import com.baeldung.web.hateoas.event.SingleResourceRetrievedEvent;
+import com.baeldung.web.util.RestPreconditions;
 import com.google.common.base.Preconditions;
 
-@Controller
+@RestController
 @RequestMapping(value = "/auth/foos")
 public class FooController {
 
@@ -42,10 +46,24 @@ public class FooController {
 
     // API
 
+    // read - one
+
+    @GetMapping(value = "/{id}")
+    public Foo findById(@PathVariable("id") final Long id, final HttpServletResponse response) {
+        final Foo resourceById = RestPreconditions.checkFound(service.findOne(id));
+
+        eventPublisher.publishEvent(new SingleResourceRetrievedEvent(this, response));
+        return resourceById;
+    }
+
     // read - all
 
-    @RequestMapping(params = { "page", "size" }, method = RequestMethod.GET)
-    @ResponseBody
+    @GetMapping
+    public List<Foo> findAll() {
+        return service.findAll();
+    }
+
+    @GetMapping(params = { "page", "size" })
     public List<Foo> findPaginated(@RequestParam("page") final int page, @RequestParam("size") final int size,
         final UriComponentsBuilder uriBuilder, final HttpServletResponse response) {
         final Page<Foo> resultPage = service.findPaginated(page, size);
@@ -59,7 +77,6 @@ public class FooController {
     }
 
     @GetMapping("/pageable")
-    @ResponseBody
     public List<Foo> findPaginatedWithPageable(Pageable pageable, final UriComponentsBuilder uriBuilder,
         final HttpServletResponse response) {
         final Page<Foo> resultPage = service.findPaginated(pageable);
@@ -74,9 +91,8 @@ public class FooController {
 
     // write
 
-    @RequestMapping(method = RequestMethod.POST)
+    @PostMapping
     @ResponseStatus(HttpStatus.CREATED)
-    @ResponseBody
     public Foo create(@RequestBody final Foo resource, final HttpServletResponse response) {
         Preconditions.checkNotNull(resource);
         final Foo foo = service.create(resource);
@@ -86,4 +102,18 @@ public class FooController {
 
         return foo;
     }
+
+    @PutMapping(value = "/{id}")
+    @ResponseStatus(HttpStatus.OK)
+    public void update(@PathVariable("id") final Long id, @RequestBody final Foo resource) {
+        Preconditions.checkNotNull(resource);
+        RestPreconditions.checkFound(service.findOne(resource.getId()));
+        service.update(resource);
+    }
+
+    @DeleteMapping(value = "/{id}")
+    @ResponseStatus(HttpStatus.OK)
+    public void delete(@PathVariable("id") final Long id) {
+        service.deleteById(id);
+    }
 }

spring-boot-rest/src/main/java/com/baeldung/web/hateoas/event/SingleResourceRetrievedEvent.java

@@ -0,0 +1,22 @@
+package com.baeldung.web.hateoas.event;
+
+import javax.servlet.http.HttpServletResponse;
+
+import org.springframework.context.ApplicationEvent;
+
+public class SingleResourceRetrievedEvent extends ApplicationEvent {
+    private final HttpServletResponse response;
+
+    public SingleResourceRetrievedEvent(final Object source, final HttpServletResponse response) {
+        super(source);
+
+        this.response = response;
+    }
+
+    // API
+
+    public HttpServletResponse getResponse() {
+        return response;
+    }
+
+}

spring-boot-rest/src/main/java/com/baeldung/web/hateoas/listener/SingleResourceRetrievedDiscoverabilityListener.java

@@ -0,0 +1,34 @@
+package com.baeldung.web.hateoas.listener;
+
+import javax.servlet.http.HttpServletResponse;
+
+import com.baeldung.web.hateoas.event.SingleResourceRetrievedEvent;
+import com.baeldung.web.util.LinkUtil;
+import org.springframework.context.ApplicationListener;
+import org.springframework.stereotype.Component;
+import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
+
+import com.google.common.base.Preconditions;
+import com.google.common.net.HttpHeaders;
+
+@Component
+class SingleResourceRetrievedDiscoverabilityListener implements ApplicationListener<SingleResourceRetrievedEvent> {
+
+    @Override
+    public void onApplicationEvent(final SingleResourceRetrievedEvent resourceRetrievedEvent) {
+        Preconditions.checkNotNull(resourceRetrievedEvent);
+
+        final HttpServletResponse response = resourceRetrievedEvent.getResponse();
+        addLinkHeaderOnSingleResourceRetrieval(response);
+    }
+
+    void addLinkHeaderOnSingleResourceRetrieval(final HttpServletResponse response) {
+        final String requestURL = ServletUriComponentsBuilder.fromCurrentRequestUri().build().toUri().toASCIIString();
+        final int positionOfLastSlash = requestURL.lastIndexOf("/");
+        final String uriForResourceCreation = requestURL.substring(0, positionOfLastSlash);
+
+        final String linkHeaderValue = LinkUtil.createLinkHeader(uriForResourceCreation, "collection");
+        response.addHeader(HttpHeaders.LINK, linkHeaderValue);
+    }
+
+}

spring-boot-rest/src/test/java/com/baeldung/web/FooControllerAppIntegrationTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.web;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+
+/**
+ * 
+ *  We'll start the whole context, but not the server. We'll mock the REST calls instead.
+ *
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureMockMvc
+public class FooControllerAppIntegrationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    public void whenFindPaginatedRequest_thenEmptyResponse() throws Exception {
+        this.mockMvc.perform(get("/auth/foos").param("page", "0")
+            .param("size", "2"))
+            .andExpect(status().isOk())
+            .andExpect(content().json("[]"));
+    }
+
+}

spring-boot-rest/src/test/java/com/baeldung/web/FooControllerWebLayerIntegrationTest.java

@@ -0,0 +1,60 @@
+package com.baeldung.web;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import java.util.Collections;
+
+import org.hamcrest.Matchers;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageImpl;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+
+import com.baeldung.persistence.model.Foo;
+import com.baeldung.persistence.service.IFooService;
+import com.baeldung.web.controller.FooController;
+import com.baeldung.web.hateoas.event.PaginatedResultsRetrievedEvent;
+
+/**
+ * 
+ *  We'll start only the web layer.
+ *
+ */
+@RunWith(SpringRunner.class)
+@WebMvcTest(FooController.class)
+public class FooControllerWebLayerIntegrationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @MockBean
+    private IFooService service;
+
+    @MockBean
+    private ApplicationEventPublisher publisher;
+
+    @Test()
+    public void givenPresentFoo_whenFindPaginatedRequest_thenPageWithFooRetrieved() throws Exception {
+        Page<Foo> page = new PageImpl<>(Collections.singletonList(new Foo("fooName")));
+        when(service.findPaginated(0, 2)).thenReturn(page);
+        doNothing().when(publisher)
+            .publishEvent(any(PaginatedResultsRetrievedEvent.class));
+
+        this.mockMvc.perform(get("/auth/foos").param("page", "0")
+            .param("size", "2"))
+            .andExpect(status().isOk())
+            .andExpect(jsonPath("$",Matchers.hasSize(1)));
+    }
+
+}