Merge branch 'master' into master

Author: SmartyAnsh

Diff for: .gitignore

@@ -19,6 +19,7 @@
 .idea/
 *.iml
 *.iws
+out/
 
 # Mac
 .DS_Store
@@ -27,6 +28,9 @@
 log/
 target/
 
+# Gradle
+.gradle/
+
 spring-openid/src/main/resources/application.properties
 .recommenders/
 /spring-hibernate4/nbproject/

Diff for: azure/README.md

@@ -1,4 +1,4 @@
 ### Relevant Articles:
 
-- [Deploy Spring Boot App to Azure](http://www.baeldung.com/spring-boot-azure)
+- [Deploy a Spring Boot App to Azure](http://www.baeldung.com/spring-boot-azure)
 

Diff for: blade/README.md

@@ -1,5 +1,5 @@
 ### Relevant Articles: 
 
-- [Blade - A Complete GuideBook](http://www.baeldung.com/blade) 
+- [Blade – A Complete Guidebook](http://www.baeldung.com/blade) 
 
-Run Integration Tests with `mvn integration-test`
+Run Integration Tests with `mvn integration-test`

Diff for: core-groovy-2/README.md

@@ -2,4 +2,6 @@
 
 ## Relevant articles:
 
+- [String Matching in Groovy](http://www.baeldung.com/)
 - [Groovy def Keyword]
+

Diff for: core-groovy-2/pom.xml

@@ -96,6 +96,15 @@
                         </configuration>
                     </execution>
                 </executions>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.20.1</version>
+                <configuration>
+                <useFile>false</useFile>
+                <includes>
+                    <include>**/*Test.java</include>
+                    <include>**/*Spec.java</include>
+                </includes>
+                </configuration>
             </plugin>
         </plugins>
     </build>

Diff for: core-groovy-2/src/test/groovy/com/baeldung/strings/StringMatchingSpec.groovy

@@ -0,0 +1,44 @@
+package com.baeldung.strings
+
+import spock.lang.Specification
+
+import java.util.regex.Pattern
+
+class StringMatchingSpec extends Specification {
+
+    def "pattern operator example"() {
+        given: "a pattern"
+        def p = ~'foo'
+
+        expect:
+        p instanceof Pattern
+
+        and: "you can use slash strings to avoid escaping of blackslash"
+        def digitPattern = ~/\d*/
+        digitPattern.matcher('4711').matches()
+    }
+
+    def "match operator example"() {
+        expect:
+        'foobar' ==~ /.*oba.*/
+
+        and: "matching is strict"
+        !('foobar' ==~ /foo/)
+    }
+
+    def "find operator example"() {
+        when: "using the find operator"
+        def matcher = 'foo and bar, baz and buz' =~ /(\w+) and (\w+)/
+
+        then: "will find groups"
+        matcher.size() == 2
+
+        and: "can access groups using array"
+        matcher[0][0] == 'foo and bar'
+        matcher[1][2] == 'buz'
+
+        and: "you can use it as a predicate"
+        'foobarbaz' =~ /bar/
+    }
+
+}

Diff for: core-groovy/README.md

@@ -8,6 +8,8 @@
 - [Types of Strings in Groovy](https://www.baeldung.com/groovy-strings)
 - [A Quick Guide to Iterating a Map in Groovy](https://www.baeldung.com/groovy-map-iterating)
 - [An Introduction to Traits in Groovy](https://www.baeldung.com/groovy-traits)
+- [Closures in Groovy](https://www.baeldung.com/groovy-closures)
+- [Finding Elements in Collections in Groovy](https://www.baeldung.com/groovy-collections-find-elements)
 - [Lists in Groovy](https://www.baeldung.com/groovy-lists)
 - [Converting a String to a Date in Groovy](https://www.baeldung.com/groovy-string-to-date)
-- [Guide to I/O in Groovy](https://www.baeldung.com/groovy-io)
+- [Guide to I/O in Groovy](https://www.baeldung.com/groovy-io)

Diff for: core-groovy/src/test/groovy/com/baeldung/strings/StringMatchingSpec.groovy

@@ -0,0 +1,44 @@
+package com.baeldung.strings
+
+import spock.lang.Specification
+
+import java.util.regex.Pattern
+
+class StringMatchingSpec extends Specification {
+
+    def "pattern operator example"() {
+        given: "a pattern"
+        def p = ~'foo'
+
+        expect:
+        p instanceof Pattern
+
+        and: "you can use slash strings to avoid escaping of blackslash"
+        def digitPattern = ~/\d*/
+        digitPattern.matcher('4711').matches()
+    }
+
+    def "match operator example"() {
+        expect:
+        'foobar' ==~ /.*oba.*/
+
+        and: "matching is strict"
+        !('foobar' ==~ /foo/)
+    }
+
+    def "find operator example"() {
+        when: "using the find operator"
+        def matcher = 'foo and bar, baz and buz' =~ /(\w+) and (\w+)/
+
+        then: "will find groups"
+        matcher.size() == 2
+
+        and: "can access groups using array"
+        matcher[0][0] == 'foo and bar'
+        matcher[1][2] == 'buz'
+
+        and: "you can use it as a predicate"
+        'foobarbaz' =~ /bar/
+    }
+
+}

Diff for: core-java-11/README.md

@@ -6,3 +6,4 @@
 - [Java 11 Nest Based Access Control](https://www.baeldung.com/java-nest-based-access-control)
 - [Exploring the New HTTP Client in Java 9 and 11](https://www.baeldung.com/java-9-http-client)
 - [An Introduction to Epsilon GC: A No-Op Experimental Garbage Collector](https://www.baeldung.com/jvm-epsilon-gc-garbage-collector)
+- [Guide to jlink](https://www.baeldung.com/jlink)

Diff for: core-java-8/README.md

@@ -3,7 +3,7 @@
 ## Core Java 8 Cookbooks and Examples
 
 ### Relevant Articles: 
-- [Java 8 Collectors](http://www.baeldung.com/java-8-collectors)
+- [Guide to Java 8’s Collectors](http://www.baeldung.com/java-8-collectors)
 - [Functional Interfaces in Java 8](http://www.baeldung.com/java-8-functional-interfaces)
 - [Java 8 – Powerful Comparison with Lambdas](http://www.baeldung.com/java-8-sort-lambda)
 - [New Features in Java 8](http://www.baeldung.com/java-8-new-features)

Diff for: core-java-9/README.md

@@ -5,26 +5,21 @@
 [Java 9 New Features](http://www.baeldung.com/new-java-9)
 
 ### Relevant Articles:
-- [Java 9 Stream API Improvements](http://www.baeldung.com/java-9-stream-api)
-- [Java 9 Convenience Factory Methods for Collections](http://www.baeldung.com/java-9-collections-factory-methods) 
+
+- [Java 9 New Features](https://www.baeldung.com/new-java-9)
 - [New Stream Collectors in Java 9](http://www.baeldung.com/java9-stream-collectors)
-- [Java 9 CompletableFuture API Improvements](http://www.baeldung.com/java-9-completablefuture)
-- [Introduction to Java 9 StackWalking API](http://www.baeldung.com/java-9-stackwalking-api)
 - [Introduction to Project Jigsaw](http://www.baeldung.com/project-jigsaw-java-modularity)
-- [Java 9 Optional API Additions](http://www.baeldung.com/java-9-optional)
-- [Java 9 Reactive Streams](http://www.baeldung.com/java-9-reactive-streams)
-- [Java 9 java.util.Objects Additions](http://www.baeldung.com/java-9-objects-new)
-- [Java 9 Variable Handles Demistyfied](http://www.baeldung.com/java-variable-handles)
+- [Java 9 Variable Handles Demystified](http://www.baeldung.com/java-variable-handles)
 - [Exploring the New HTTP Client in Java 9 and 11](http://www.baeldung.com/java-9-http-client)
 - [Method Handles in Java](http://www.baeldung.com/java-method-handles)
 - [Introduction to Chronicle Queue](http://www.baeldung.com/java-chronicle-queue)
-- [A Guide to Java 9 Modularity](http://www.baeldung.com/java-9-modularity)
 - [Optional orElse Optional](http://www.baeldung.com/java-optional-or-else-optional)
-- [Java 9 java.lang.Module API](http://www.baeldung.com/java-9-module-api)
 - [Iterate Through a Range of Dates in Java](https://www.baeldung.com/java-iterate-date-range)
 - [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)
 - [Immutable Set in Java](https://www.baeldung.com/java-immutable-set)
 - [Multi-Release Jar Files](https://www.baeldung.com/java-multi-release-jar)
 - [Ahead of Time Compilation (AoT)](https://www.baeldung.com/ahead-of-time-compilation)
+- [Java 9 Process API Improvements](https://www.baeldung.com/java-9-process-api)
+- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
+
 

Diff for: core-java-collections/README.md

@@ -3,7 +3,7 @@
 ## Core Java Collections Cookbooks and Examples
 
 ### Relevant Articles: 
-- [Java - Combine Multiple Collections](http://www.baeldung.com/java-combine-multiple-collections)
+- [Java – Combine Multiple Collections](http://www.baeldung.com/java-combine-multiple-collections)
 - [HashSet and TreeSet Comparison](http://www.baeldung.com/java-hashset-vs-treeset)
 - [Collect a Java Stream to an Immutable Collection](http://www.baeldung.com/java-stream-immutable-collection)
 - [Introduction to the Java ArrayDeque](http://www.baeldung.com/java-array-deque)

Diff for: core-java-concurrency-advanced/README.md

@@ -12,14 +12,14 @@
 - [Guide to the Java Phaser](http://www.baeldung.com/java-phaser)
 - [An Introduction to Atomic Variables in Java](http://www.baeldung.com/java-atomic-variables)
 - [CyclicBarrier in Java](http://www.baeldung.com/java-cyclic-barrier)
-- [Guide to Volatile Keyword in Java](http://www.baeldung.com/java-volatile)
+- [Guide to the Volatile Keyword in Java](http://www.baeldung.com/java-volatile)
 - [Semaphores in Java](http://www.baeldung.com/java-semaphore)
 - [Daemon Threads in Java](http://www.baeldung.com/java-daemon-thread)
 - [Priority-based Job Scheduling in Java](http://www.baeldung.com/java-priority-job-schedule)
 - [Brief Introduction to Java Thread.yield()](https://www.baeldung.com/java-thread-yield)
 - [Print Even and Odd Numbers Using 2 Threads](https://www.baeldung.com/java-even-odd-numbers-with-2-threads)
 - [Java CyclicBarrier vs CountDownLatch](https://www.baeldung.com/java-cyclicbarrier-countdownlatch)
 - [Guide to the Fork/Join Framework in Java](http://www.baeldung.com/java-fork-join)
-- [A Guide to ThreadLocalRandom in Java](http://www.baeldung.com/java-thread-local-random)
+- [Guide to ThreadLocalRandom in Java](http://www.baeldung.com/java-thread-local-random)
 - [The Thread.join() Method in Java](http://www.baeldung.com/java-thread-join)
 - [Passing Parameters to Java Threads](https://www.baeldung.com/java-thread-parameters)

Diff for: core-java-concurrency-basic/README.md

@@ -7,13 +7,13 @@
 - [A Guide to the Java ExecutorService](http://www.baeldung.com/java-executor-service-tutorial)
 - [Guide to java.util.concurrent.Future](http://www.baeldung.com/java-future)
 - [Difference Between Wait and Sleep in Java](http://www.baeldung.com/java-wait-and-sleep)
-- [Guide to Synchronized Keyword in Java](http://www.baeldung.com/java-synchronized)
+- [Guide to the Synchronized Keyword in Java](http://www.baeldung.com/java-synchronized)
 - [Overview of the java.util.concurrent](http://www.baeldung.com/java-util-concurrent)
 - [Implementing a Runnable vs Extending a Thread](http://www.baeldung.com/java-runnable-vs-extending-thread)
 - [How to Kill a Java Thread](http://www.baeldung.com/java-thread-stop)
-- [ExecutorService - Waiting for Threads to Finish](http://www.baeldung.com/java-executor-wait-for-threads)
+- [ExecutorService – Waiting for Threads to Finish](http://www.baeldung.com/java-executor-wait-for-threads)
 - [wait and notify() Methods in Java](http://www.baeldung.com/java-wait-notify)
 - [Life Cycle of a Thread in Java](http://www.baeldung.com/java-thread-lifecycle)
 - [Runnable vs. Callable in Java](http://www.baeldung.com/java-runnable-callable)
-- [What is Thread-Safety and How to Achieve it](https://www.baeldung.com/java-thread-safety)
+- [What is Thread-Safety and How to Achieve it?](https://www.baeldung.com/java-thread-safety)
 - [How to Start a Thread in Java](https://www.baeldung.com/java-start-thread)

Diff for: core-java-io/README.md

@@ -6,15 +6,15 @@
 - [How to Read a Large File Efficiently with Java](http://www.baeldung.com/java-read-lines-large-file)
 - [Java InputStream to String](http://www.baeldung.com/convert-input-stream-to-string)
 - [Java – Write to File](http://www.baeldung.com/java-write-to-file)
-- [Java - Convert File to InputStream](http://www.baeldung.com/convert-file-to-input-stream)
+- [Java – Convert File to InputStream](http://www.baeldung.com/convert-file-to-input-stream)
 - [Java Scanner](http://www.baeldung.com/java-scanner)
 - [Java – Byte Array to Writer](http://www.baeldung.com/java-convert-byte-array-to-writer)
 - [Java – Directory Size](http://www.baeldung.com/java-folder-size)
 - [Differences Between the Java WatchService API and the Apache Commons IO Monitor Library](http://www.baeldung.com/java-watchservice-vs-apache-commons-io-monitor-library)
 - [File Size in Java](http://www.baeldung.com/java-file-size)
 - [Comparing getPath(), getAbsolutePath(), and getCanonicalPath() in Java](http://www.baeldung.com/java-path)
 - [Using Java MappedByteBuffer](http://www.baeldung.com/java-mapped-byte-buffer)
-- [Copy a File with Java](http://www.baeldung.com/java-copy-file)
+- [How to Copy a File with Java](http://www.baeldung.com/java-copy-file)
 - [Java – Append Data to a File](http://www.baeldung.com/java-append-to-file)
 - [FileNotFoundException in Java](http://www.baeldung.com/java-filenotfound-exception)
 - [How to Read a File in Java](http://www.baeldung.com/reading-file-in-java)

Diff for: core-java-jvm/README.md

@@ -3,4 +3,4 @@
 ## Core Java JVM Cookbooks and Examples
 
 ### Relevant Articles: 
-- [Method Inlining in the JVM](http://www.baeldung.com/method-inlining-in-the-jvm/)
+- [Method Inlining in the JVM](https://www.baeldung.com/jvm-method-inlining)

Diff for: core-java-lambdas/pom.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <artifactId>core-java-lambdas</artifactId>
+  <version>0.1.0-SNAPSHOT</version>
+  <name>core-java</name>
+  <packaging>jar</packaging>
+
+  <parent>
+    <groupId>com.baeldung</groupId>
+    <artifactId>parent-java</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <relativePath>../parent-java</relativePath>
+  </parent>
+
+
+</project>

Diff for: core-java-lambdas/src/main/java/com/baeldung/lambdas/LambdaVariables.java

@@ -0,0 +1,88 @@
+package com.baeldung.lambdas;
+
+import java.util.Random;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.function.Supplier;
+import java.util.stream.IntStream;
+
+/**
+ * Class with examples about working with capturing lambdas.
+ */
+public class LambdaVariables {
+
+    private volatile boolean run = true;
+    private int start = 0;
+
+    private ExecutorService executor = Executors.newFixedThreadPool(3);
+
+    public static void main(String[] args) {
+        new LambdaVariables().localVariableMultithreading();
+    }
+
+    Supplier<Integer> incrementer(int start) {
+        return () -> start; // can't modify start parameter inside the lambda
+    }
+
+    Supplier<Integer> incrementer() {
+        return () -> start++;
+    }
+
+    public void localVariableMultithreading() {
+        boolean run = true;
+        executor.execute(() -> {
+            while (run) {
+                // do operation
+            }
+        });
+        // commented because it doesn't compile, it's just an example of non-final local variables in lambdas
+        // run = false;
+    }
+
+    public void instanceVariableMultithreading() {
+        executor.execute(() -> {
+            while (run) {
+                // do operation
+            }
+        });
+
+        run = false;
+    }
+
+    /**
+     * WARNING: always avoid this workaround!!
+     */
+    public void workaroundSingleThread() {
+        int[] holder = new int[] { 2 };
+        IntStream sums = IntStream
+          .of(1, 2, 3)
+          .map(val -> val + holder[0]);
+
+        holder[0] = 0;
+
+        System.out.println(sums.sum());
+    }
+
+    /**
+     * WARNING: always avoid this workaround!!
+     */
+    public void workaroundMultithreading() {
+        int[] holder = new int[] { 2 };
+        Runnable runnable = () -> System.out.println(IntStream
+          .of(1, 2, 3)
+          .map(val -> val + holder[0])
+          .sum());
+
+        new Thread(runnable).start();
+
+        // simulating some processing
+        try {
+            Thread.sleep(new Random().nextInt(3) * 1000L);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        holder[0] = 0;
+    }
+
+}