Merge pull request #73 from eugenp/master

update

aws-lambda/README.md

@@ -5,3 +5,4 @@ This module contains articles about AWS Lambda
 ### Relevant Articles: 
 - [Using AWS Lambda with API Gateway](https://www.baeldung.com/aws-lambda-api-gateway)
 - [Introduction to AWS Serverless Application Model](https://www.baeldung.com/aws-serverless)
+- [How to Implement Hibernate in an AWS Lambda Function in Java](https://www.baeldung.com/java-aws-lambda-hibernate)

core-groovy-strings/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [How to Remove a Prefix From Strings in Groovy](https://www.baeldung.com/groovy-remove-string-prefix)

core-groovy-strings/pom.xml

@@ -0,0 +1,122 @@
+<?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-groovy-strings</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>core-groovy-strings</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy</artifactId>
+            <version>${groovy.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy-all</artifactId>
+            <version>${groovy-all.version}</version>
+            <type>pom</type>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy-dateutil</artifactId>
+            <version>${groovy.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy-sql</artifactId>
+            <version>${groovy-sql.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-runner</artifactId>
+            <version>${junit.platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hsqldb</groupId>
+            <artifactId>hsqldb</artifactId>
+            <version>${hsqldb.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.spockframework</groupId>
+            <artifactId>spock-core</artifactId>
+            <version>${spock-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.gmavenplus</groupId>
+                <artifactId>gmavenplus-plugin</artifactId>
+                <version>${gmavenplus-plugin.version}</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>addSources</goal>
+                            <goal>addTestSources</goal>
+                            <goal>compile</goal>
+                            <goal>compileTests</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <artifactId>maven-failsafe-plugin</artifactId>
+                <version>${maven-failsafe-plugin.version}</version>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.junit.platform</groupId>
+                        <artifactId>junit-platform-surefire-provider</artifactId>
+                        <version>${junit.platform.version}</version>
+                    </dependency>
+                </dependencies>
+                <executions>
+                    <execution>
+                        <id>junit5</id>
+                        <goals>
+                            <goal>integration-test</goal>
+                            <goal>verify</goal>
+                        </goals>
+                        <configuration>
+                            <includes>
+                                <include>**/*Test5.java</include>
+                            </includes>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <repositories>
+        <repository>
+            <id>central</id>
+            <url>https://jcenter.bintray.com</url>
+        </repository>
+    </repositories>
+
+    <properties>
+        <junit.platform.version>1.0.0</junit.platform.version>
+        <groovy.version>2.5.6</groovy.version>
+        <groovy-all.version>2.5.6</groovy-all.version>
+        <groovy-sql.version>2.5.6</groovy-sql.version>
+        <hsqldb.version>2.4.0</hsqldb.version>
+        <spock-core.version>1.1-groovy-2.4</spock-core.version>
+        <gmavenplus-plugin.version>1.6</gmavenplus-plugin.version>
+    </properties>
+
+</project>

core-groovy-strings/src/test/groovy/com/baeldung/removeprefix/RemovePrefixTest.groovy

@@ -0,0 +1,70 @@
+package com.baeldung.removeprefix
+
+import org.junit.Assert
+import org.junit.Test
+
+class RemovePrefixTest {
+
+
+    @Test
+    public void whenCasePrefixIsRemoved_thenReturnTrue() {
+        def trimPrefix = {
+            it.startsWith('Groovy-') ? it.minus('Groovy-') : it
+        }
+        
+        def actual = trimPrefix("Groovy-Tutorials at Baeldung")
+        def expected = "Tutorials at Baeldung"
+
+        Assert.assertEquals(expected, actual)
+    }
+
+    @Test
+    public void whenPrefixIsRemoved_thenReturnTrue() {
+
+        String prefix = "groovy-"
+        String trimPrefix = "Groovy-Tutorials at Baeldung"
+        def actual;
+        if(trimPrefix.startsWithIgnoreCase(prefix)) {
+            actual = trimPrefix.substring(prefix.length())
+        }
+        
+        def expected = "Tutorials at Baeldung"
+
+        Assert.assertEquals(expected, actual)
+    }
+
+    @Test
+    public void whenPrefixIsRemovedUsingRegex_thenReturnTrue() {
+
+        def regex = ~"^([Gg])roovy-"
+        String trimPrefix = "Groovy-Tutorials at Baeldung"
+        String actual = trimPrefix - regex
+        
+        def expected = "Tutorials at Baeldung"
+
+        Assert.assertEquals(expected, actual)
+    }
+
+    @Test 
+    public void whenPrefixIsRemovedUsingReplaceFirst_thenReturnTrue() {
+        def regex = ~"^groovy" 
+        String trimPrefix = "groovyTutorials at Baeldung's groovy page" 
+        String actual = trimPrefix.replaceFirst(regex, "")
+        
+        def expected = "Tutorials at Baeldung's groovy page"
+        
+        Assert.assertEquals(expected, actual)
+    }
+
+    @Test
+    public void whenPrefixIsRemovedUsingReplaceAll_thenReturnTrue() {
+
+        String trimPrefix = "groovyTutorials at Baeldung groovy"
+        String actual = trimPrefix.replaceAll(/^groovy/, "")
+        
+        def expected = "Tutorials at Baeldung groovy"
+
+        Assert.assertEquals(expected, actual)
+    }
+
+}

core-java-modules/core-java-10/src/test/java/com/baeldung/AppUnitTest.java

@@ -7,7 +7,7 @@ import junit.framework.TestSuite;
 /**
  * Unit test for simple App.
  */
-public class AppTest 
+public class AppUnitTest
     extends TestCase
 {
     /**
@@ -15,7 +15,7 @@ public class AppTest
      *
      * @param testName name of the test case
      */
-    public AppTest( String testName )
+    public AppUnitTest(String testName )
     {
         super( testName );
     }
@@ -25,7 +25,7 @@ public class AppTest
      */
     public static Test suite()
     {
-        return new TestSuite( AppTest.class );
+        return new TestSuite( AppUnitTest.class );
     }
 
     /**

core-java-modules/core-java-12/src/test/java/com/baeldung/string/StringAPIUnitTest.java

@@ -5,7 +5,7 @@ import static org.hamcrest.MatcherAssert.assertThat;
 
 import org.junit.Test;
 
-public class StringAPITest {
+public class StringAPIUnitTest {
 
     @Test
     public void whenPositiveArgument_thenReturnIndentedString() {

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/record/PersonUnitTest.java

@@ -7,7 +7,7 @@ import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 
-public class PersonTest {
+public class PersonUnitTest {
 
     @Test
     public void givenSameNameAndAddress_whenEquals_thenPersonsEqual() {

core-java-modules/core-java-9/pom.xml

@@ -44,6 +44,16 @@
             <artifactId>commons-collections4</artifactId>
             <version>${commons-collections4.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.11</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>2.7</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -77,6 +87,7 @@
         <maven.compiler.target>1.9</maven.compiler.target>
         <guava.version>25.1-jre</guava.version>
         <commons-collections4.version>4.1</commons-collections4.version>
+        <commons-collections3.version>3.2.2</commons-collections3.version>
     </properties>
 
 </project>

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/methodhandles/MethodHandlesUnitTest.java

@@ -17,7 +17,7 @@ import org.junit.Test;
 /**
  * Test case for the {@link MethodHandles} API
  */
-public class MethodHandlesTest {
+public class MethodHandlesUnitTest {
 
     @Test
     public void givenConcatMethodHandle_whenInvoked_thenCorrectlyConcatenated() throws Throwable {

core-java-modules/core-java-arrays-guides/README.md

@@ -6,3 +6,4 @@ This module contains complete guides about arrays in Java
 - [Arrays in Java: A Reference Guide](https://www.baeldung.com/java-arrays-guide)
 - [Guide to the java.util.Arrays Class](https://www.baeldung.com/java-util-arrays)
 - [What is \[Ljava.lang.Object;?](https://www.baeldung.com/java-tostring-array)
+- [Guide to ArrayStoreException](https://www.baeldung.com/java-arraystoreexception)

core-java-modules/core-java-collections-3/src/main/java/com/baeldung/collections/removeallperformance/HashSetBenchmark.java

@@ -0,0 +1,86 @@
+package com.baeldung.collections.removeallperformance;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.lang3.RandomStringUtils;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import com.baeldung.collections.containsperformance.Employee;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Warmup(iterations = 5)
+public class HashSetBenchmark {
+
+    @State(Scope.Thread)
+    public static class MyState {
+        private Set<Employee> employeeSet1 = new HashSet<>();
+        private List<Employee> employeeList1 = new ArrayList<>();
+        private Set<Employee> employeeSet2 = new HashSet<>();
+        private List<Employee> employeeList2 = new ArrayList<>();
+
+        private long set1Size = 60000;
+        private long list1Size = 50000;
+        private long set2Size = 50000;
+        private long list2Size = 60000;
+
+        @Setup(Level.Trial)
+        public void setUp() {
+
+            for (long i = 0; i < set1Size; i++) {
+                employeeSet1.add(new Employee(i, RandomStringUtils.random(7, true, false)));
+            }
+
+            for (long i = 0; i < list1Size; i++) {
+                employeeList1.add(new Employee(i, RandomStringUtils.random(7, true, false)));
+            }
+
+            for (long i = 0; i < set2Size; i++) {
+                employeeSet2.add(new Employee(i, RandomStringUtils.random(7, true, false)));
+            }
+
+            for (long i = 0; i < list2Size; i++) {
+                employeeList2.add(new Employee(i, RandomStringUtils.random(7, true, false)));
+            }
+
+        }
+
+    }
+
+    @Benchmark
+    public boolean given_SizeOfHashsetGreaterThanSizeOfCollection_When_RemoveAllFromHashSet_Then_GoodPerformance(MyState state) {
+        return state.employeeSet1.removeAll(state.employeeList1);
+    }
+
+    @Benchmark
+    public boolean given_SizeOfHashsetSmallerThanSizeOfCollection_When_RemoveAllFromHashSet_Then_BadPerformance(MyState state) {
+        return state.employeeSet2.removeAll(state.employeeList2);
+    }
+
+    public static void main(String[] args) throws Exception {
+        Options options = new OptionsBuilder().include(HashSetBenchmark.class.getSimpleName())
+            .threads(1)
+            .forks(1)
+            .shouldFailOnError(true)
+            .shouldDoGC(true)
+            .jvmArgs("-server")
+            .build();
+        new Runner(options).run();
+    }
+
+}

core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/hashset/HashSetUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.collections.hashset;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+class HashSetUnitTest {
+
+    @Test
+    void whenRemoveAllFromHashset_thenRemovesAllElementsFromHashsetThatArePresentInCollection() {
+        Set<Integer> set = new HashSet<>();
+        Collection<Integer> collection = new ArrayList<>();
+        set.add(1);
+        set.add(2);
+        set.add(3);
+        set.add(4);
+        collection.add(1);
+        collection.add(3);
+
+        set.removeAll(collection);
+
+        assertEquals(2, set.size());
+        Integer[] actualElements = new Integer[set.size()];
+        Integer[] expectedElements = new Integer[] { 2, 4 };
+        assertArrayEquals(expectedElements, set.toArray(actualElements));
+    }
+
+}

core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/mapfirstpair/MapFirstPairUnitTest.java

@@ -15,21 +15,24 @@ import org.junit.Test;
 public class MapFirstPairUnitTest {
 
     private Map.Entry<Integer, String> getFirstPairUsingIterator(Map<Integer, String> map) {
-        if (map == null || map.size() == 0)
+        if (map == null || map.size() == 0) {
             return null;
+        }
 
         Iterator<Map.Entry<Integer, String>> iterator = map.entrySet()
             .iterator();
 
-        if (iterator.hasNext())
+        if (iterator.hasNext()) {
             return iterator.next();
+        }
 
         return null;
     }
 
     private Map.Entry<Integer, String> getFirstPairUsingStream(Map<Integer, String> map) {
-        if (map == null || map.size() == 0)
+        if (map == null || map.size() == 0) {
             return null;
+        }
 
         Set<Map.Entry<Integer, String>> entrySet = map.entrySet();
 

core-java-modules/core-java-date-operations-1/src/test/java/com/baeldung/date/DateDiffUnitTest.java

@@ -1,6 +1,8 @@
 package com.baeldung.date;
 
-import static org.junit.Assert.assertEquals;
+import org.joda.time.Days;
+import org.joda.time.Minutes;
+import org.junit.Test;
 
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
@@ -16,7 +18,7 @@ import java.util.Locale;
 import java.util.TimeZone;
 import java.util.concurrent.TimeUnit;
 
-import org.junit.Test;
+import static org.junit.Assert.*;
 
 public class DateDiffUnitTest {
 
@@ -29,18 +31,39 @@ public class DateDiffUnitTest {
         long diffInMillies = Math.abs(secondDate.getTime() - firstDate.getTime());
         long diff = TimeUnit.DAYS.convert(diffInMillies, TimeUnit.MILLISECONDS);
 
-        assertEquals(diff, 6);
+        assertEquals(6, diff);
     }
 
     @Test
-    public void givenTwoDatesInJava8_whenDifferentiating_thenWeGetSix() {
-        LocalDate now = LocalDate.now();
-        LocalDate sixDaysBehind = now.minusDays(6);
+    public void givenTwoDatesInJava8_whenUsingPeriodGetDays_thenWorks() {
+        LocalDate aDate = LocalDate.of(2020, 9, 11);
+        LocalDate sixDaysBehind = aDate.minusDays(6);
 
-        Period period = Period.between(now, sixDaysBehind);
+        Period period = Period.between(aDate, sixDaysBehind);
         int diff = Math.abs(period.getDays());
 
-        assertEquals(diff, 6);
+        assertEquals(6, diff);
+    }
+
+    @Test
+    public void givenTwoDatesInJava8_whenUsingPeriodGetDays_thenDoesNotWork() {
+        LocalDate aDate = LocalDate.of(2020, 9, 11);
+        LocalDate sixtyDaysBehind = aDate.minusDays(60);
+        Period period = Period.between(aDate, sixtyDaysBehind);
+        int diff = Math.abs(period.getDays());
+        //not equals
+        assertNotEquals(60, diff);
+    }
+
+    @Test
+    public void givenTwoDatesInJava8_whenUsingPeriod_thenWeGet0Year1Month29Days() {
+        LocalDate aDate = LocalDate.of(2020, 9, 11);
+        LocalDate sixtyDaysBehind = aDate.minusDays(60);
+        Period period = Period.between(aDate, sixtyDaysBehind);
+        int years = Math.abs(period.getYears());
+        int months = Math.abs(period.getMonths());
+        int days = Math.abs(period.getDays());
+        assertArrayEquals(new int[] { 0, 1, 29 }, new int[] { years, months, days });
     }
 
     @Test
@@ -51,7 +74,7 @@ public class DateDiffUnitTest {
         Duration duration = Duration.between(now, sixMinutesBehind);
         long diff = Math.abs(duration.toMinutes());
 
-        assertEquals(diff, 6);
+        assertEquals(6, diff);
     }
 
     @Test
@@ -61,7 +84,7 @@ public class DateDiffUnitTest {
 
         long diff = ChronoUnit.SECONDS.between(now, tenSecondsLater);
 
-        assertEquals(diff, 10);
+        assertEquals(10, diff);
     }
 
     @Test
@@ -69,9 +92,9 @@ public class DateDiffUnitTest {
         LocalDateTime ldt = LocalDateTime.now();
         ZonedDateTime now = ldt.atZone(ZoneId.of("America/Montreal"));
         ZonedDateTime sixDaysBehind = now.withZoneSameInstant(ZoneId.of("Asia/Singapore"))
-            .minusDays(6);
+                                         .minusDays(6);
         long diff = ChronoUnit.DAYS.between(sixDaysBehind, now);
-        assertEquals(diff, 6);
+        assertEquals(6, diff);
     }
 
     @Test
@@ -81,7 +104,7 @@ public class DateDiffUnitTest {
 
         long diff = now.until(tenSecondsLater, ChronoUnit.SECONDS);
 
-        assertEquals(diff, 10);
+        assertEquals(10, diff);
     }
 
     @Test
@@ -89,10 +112,9 @@ public class DateDiffUnitTest {
         org.joda.time.LocalDate now = org.joda.time.LocalDate.now();
         org.joda.time.LocalDate sixDaysBehind = now.minusDays(6);
 
-        org.joda.time.Period period = new org.joda.time.Period(now, sixDaysBehind);
-        long diff = Math.abs(period.getDays());
+        long diff = Math.abs(Days.daysBetween(now, sixDaysBehind).getDays());
 
-        assertEquals(diff, 6);
+        assertEquals(6, diff);
     }
 
     @Test
@@ -100,8 +122,9 @@ public class DateDiffUnitTest {
         org.joda.time.LocalDateTime now = org.joda.time.LocalDateTime.now();
         org.joda.time.LocalDateTime sixMinutesBehind = now.minusMinutes(6);
 
-        org.joda.time.Period period = new org.joda.time.Period(now, sixMinutesBehind);
-        long diff = Math.abs(period.getDays());
+        long diff = Math.abs(Minutes.minutesBetween(now, sixMinutesBehind).getMinutes());
+        assertEquals(6, diff);
+
     }
 
     @Test
@@ -111,6 +134,6 @@ public class DateDiffUnitTest {
 
         long diff = Math.abs(now.numDaysFrom(sixDaysBehind));
 
-        assertEquals(diff, 6);
+        assertEquals(6, diff);
     }
-}
+}

core-java-modules/core-java-datetime-string/src/test/java/com/baeldung/timestamp/TimestampToStringConverterUnitTest.java

@@ -6,7 +6,7 @@ import org.junit.jupiter.api.Test;
 import java.sql.Timestamp;
 import java.time.format.DateTimeFormatter;
 
-public class TimestampToStringConverterTest {
+public class TimestampToStringConverterUnitTest {
 
     @Test
     public void givenDatePattern_whenFormatting_thenResultingStringIsCorrect() {

core-java-modules/core-java-exceptions-3/README.md

@@ -1,3 +1,5 @@
 ### Relevant Articles:
 
 - [NoSuchMethodError in Java](https://www.baeldung.com/java-nosuchmethod-error)
+- [IllegalArgumentException or NullPointerException for a Null Parameter?](https://www.baeldung.com/java-illegalargumentexception-or-nullpointerexception)
+- [IllegalMonitorStateException in Java](https://www.baeldung.com/java-illegalmonitorstateexception)

core-java-modules/core-java-io-3/README.md

@@ -9,4 +9,6 @@ This module contains articles about core Java input and output (IO)
 - [Check If a File or Directory Exists in Java](https://www.baeldung.com/java-file-directory-exists)
 - [Copy a Directory in Java](https://www.baeldung.com/java-copy-directory)
 - [Java Files Open Options](https://www.baeldung.com/java-file-options)
+- [Creating Temporary Directories in Java](https://www.baeldung.com/java-temp-directories)
+- [Reading a Line at a Given Line Number From a File in Java](https://www.baeldung.com/java-read-line-at-number)
 - [[<-- Prev]](/core-java-modules/core-java-io-2)

core-java-modules/core-java-io-3/src/test/java/com/baeldung/emptiness/DirectoryEmptinessUnitTest.java

@@ -4,6 +4,7 @@ import org.junit.Test;
 
 import java.io.File;
 import java.io.IOException;
+import java.net.URISyntaxException;
 import java.nio.file.DirectoryStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -20,8 +21,8 @@ public class DirectoryEmptinessUnitTest {
     }
 
     @Test
-    public void givenPath_whenNotDirectory_thenReturnsFalse() throws IOException {
-        Path aFile = Paths.get(getClass().getResource("/notDir.txt").getPath());
+    public void givenPath_whenNotDirectory_thenReturnsFalse() throws IOException, URISyntaxException {
+        Path aFile = Paths.get(getClass().getResource("/notDir.txt").toURI());
         assertThat(isEmpty(aFile)).isFalse();
     }
 

core-java-modules/core-java-io-3/src/test/java/com/baeldung/existence/ExistenceUnitTest.java

@@ -4,10 +4,7 @@ import org.junit.Test;
 
 import java.io.File;
 import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.LinkOption;
-import java.nio.file.Path;
-import java.nio.file.Paths;
+import java.nio.file.*;
 import java.util.concurrent.ThreadLocalRandom;
 
 import static org.junit.Assert.assertFalse;
@@ -47,8 +44,18 @@ public class ExistenceUnitTest {
     public void givenSymbolicLink_whenTargetDoesNotExists_thenFollowOrNotBasedOnTheOptions() throws IOException {
         Path target = Files.createTempFile("baeldung", "target");
         Path symbol = Paths.get("test-link-" + ThreadLocalRandom.current().nextInt());
+        Path symbolicLink = null;
+
+        try {
+            symbolicLink = Files.createSymbolicLink(symbol, target);
+        } catch (FileSystemException ex) {
+            System.out.println("Your OS security policy prevents the current user from creating symbolic links.\n" +
+                    "Most probably you're running Windows with UAC.\n" +
+                    "If this is the case, please see - https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/create-symbolic-links\n" +
+                    "You must change your security settings to run this test under Windows.");
+            return;
+        }
 
-        Path symbolicLink = Files.createSymbolicLink(symbol, target);
         assertTrue(Files.exists(symbolicLink));
         assertTrue(Files.isSymbolicLink(symbolicLink));
         assertFalse(Files.isSymbolicLink(target));

core-java-modules/core-java-io-3/src/test/java/com/baeldung/tempdirectory/TemporaryDirectoriesUnitTest.java

@@ -4,6 +4,7 @@ import org.apache.commons.io.FileUtils;
 import org.junit.Test;
 
 import java.io.IOException;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -66,10 +67,16 @@ public class TemporaryDirectoriesUnitTest {
 
     @Test
     public void givenTempDirWithPrefixWithFileAttrs_whenCreatePlainJava_thenAttributesAreSet() throws IOException {
-        final FileAttribute<Set<PosixFilePermission>> attrs = PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("r--------"));
+        boolean isPosix = FileSystems.getDefault().supportedFileAttributeViews().contains("posix");
 
-        final Path tmpdir = Files.createTempDirectory(Paths.get("target"), "tmpDirPrefix", attrs);
-        assertThat(tmpdir.toFile().getPath()).startsWith("target");
-        assertThat(tmpdir.toFile().canWrite()).isFalse();
+        if(!isPosix){
+            System.out.println("You must be under a Posix Compliant Filesystem to run this test.");
+        } else {
+            final FileAttribute<Set<PosixFilePermission>> attrs = PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("r--------"));
+
+            final Path tmpdir = Files.createTempDirectory(Paths.get("target"), "tmpDirPrefix", attrs);
+            assertThat(tmpdir.toFile().getPath()).startsWith("target");
+            assertThat(tmpdir.toFile().canWrite()).isFalse();
+        }
     }
 }

core-java-modules/core-java-jpms/decoupling-pattern1/consumermodule/pom.xml

@@ -17,7 +17,7 @@
     <dependencies>
         <dependency>
             <groupId>com.baeldung.servicemodule</groupId>
-            <artifactId>servicemodule</artifactId>
+            <artifactId>servicemodule1</artifactId>
             <version>${servicemodule.version}</version>
         </dependency>
     </dependencies>

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/pom.xml

@@ -4,7 +4,8 @@
     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>servicemodule</artifactId>
+    <groupId>com.baeldung.servicemodule</groupId>
+    <artifactId>servicemodule1</artifactId>
     <packaging>jar</packaging>
 
     <parent>

core-java-modules/core-java-jpms/decoupling-pattern2/providermodule/pom.xml

@@ -17,7 +17,7 @@
     <dependencies>
         <dependency>
             <groupId>com.baeldung.servicemodule</groupId>
-            <artifactId>servicemodule</artifactId>
+            <artifactId>servicemodule2</artifactId>
             <version>${servicemodule.version}</version>
         </dependency>
     </dependencies>

core-java-modules/core-java-jpms/decoupling-pattern2/servicemodule/pom.xml

@@ -4,7 +4,8 @@
     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>servicemodule</artifactId>
+    <groupId>com.baeldung.servicemodule</groupId>
+    <artifactId>servicemodule2</artifactId>
     <version>1.0</version>
 
     <parent>

core-java-modules/core-java-lang-3/README.md

@@ -5,4 +5,5 @@ This module contains articles about core features in the Java language
 - [Class.isInstance vs Class.isAssignableFrom](https://www.baeldung.com/java-isinstance-isassignablefrom)
 - [Converting a Java String Into a Boolean](https://www.baeldung.com/java-string-to-boolean)
 - [When are Static Variables Initialized in Java?](https://www.baeldung.com/java-static-variables-initialization)
+- [Checking if a Class Exists in Java](https://www.baeldung.com/java-check-class-exists)
 - [[<-- Prev]](/core-java-modules/core-java-lang-2)

core-java-modules/core-java-lang-math-2/README.md

@@ -13,4 +13,5 @@
 - [Convert Latitude and Longitude to a 2D Point in Java](https://www.baeldung.com/java-convert-latitude-longitude)
 - [Debugging with Eclipse](https://www.baeldung.com/eclipse-debugging)
 - [Matrix Multiplication in Java](https://www.baeldung.com/java-matrix-multiplication)
+- [Largest Power of 2 That Is Less Than the Given Number](https://www.baeldung.com/java-largest-power-of-2-less-than-number)
 - More articles: [[<-- Prev]](/core-java-modules/core-java-lang-math)

core-java-modules/core-java-lang-oop-methods/README.md

@@ -9,3 +9,4 @@ This module contains articles about methods in Java
 - [Java equals() and hashCode() Contracts](https://www.baeldung.com/java-equals-hashcode-contracts)
 - [Guide to hashCode() in Java](https://www.baeldung.com/java-hashcode)
 - [The Covariant Return Type in Java](https://www.baeldung.com/java-covariant-return-type)
+- [Does a Method’s Signature Include the Return Type in Java?](https://www.baeldung.com/java-method-signature-return-type)

core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/signature/OverloadingErrors.java

@@ -0,0 +1,72 @@
+package com.baeldung.signature;
+
+import java.io.Serializable;
+
+public class OverloadingErrors<T extends Serializable> {
+
+    public void print() {
+        System.out.println("Signature is: print()");
+    }
+
+    /*
+    // Uncommenting this method will lead to a compilation error: java: method print() is already defined in class
+    // The method signature is independent from return type
+    public int print() {
+        System.out.println("Signature is: print()");
+        return 0;
+    }
+    */
+
+    /*
+    // Uncommenting this method will lead to a compilation error: java: method print() is already defined in class
+    // The method signature is independent from modifiers
+    private final void print() {
+        System.out.println("Signature is: print()");
+    }
+    */
+
+    /*
+    // Uncommenting this method will lead to a compilation error: java: method print() is already defined in class
+    // The method signature is independent from thrown exception declaration
+    public void print() throws IllegalStateException {
+        System.out.println("Signature is: print()");
+        throw new IllegalStateException();
+    }
+    */
+
+    public void print(int parameter) {
+        System.out.println("Signature is: print(int)");
+    }
+
+    /*
+    // Uncommenting this method will lead to a compilation error: java: method print(int) is already defined in class
+    // The method signature is independent from parameter names
+    public void print(int anotherParameter) {
+        System.out.println("Signature is: print(int)");
+    }
+    */
+
+    public void printElement(T t) {
+        System.out.println("Signature is: printElement(T)");
+    }
+
+    /*
+    // Uncommenting this method will lead to a compilation error: java: name clash: printElement(java.io.Serializable) and printElement(T) have the same erasure
+    // Even though the signatures appear different, the compiler cannot statically bind the correct method after type erasure
+    public void printElement(Serializable o) {
+        System.out.println("Signature is: printElement(Serializable)");
+    }
+    */
+
+    public void print(Object... parameter) {
+        System.out.println("Signature is: print(Object...)");
+    }
+
+    /*
+    // Uncommenting this method will lead to a compilation error: java cannot declare both sum(Object...) and sum(Object[])
+    // Even though the signatures appear different, after compilation they both resolve to sum(Object[])
+    public void print(Object[] parameter) {
+        System.out.println("Signature is: print(Object[])");
+    }
+    */
+}

core-java-modules/core-java-lang-oop-methods/src/main/java/com/baeldung/signature/StaticBinding.java

@@ -0,0 +1,46 @@
+package com.baeldung.signature;
+
+public class StaticBinding {
+
+    public Number sum(Integer term1, Integer term2) {
+        System.out.println("Adding integers");
+        return term1 + term2;
+    }
+
+    public Number sum(Number term1, Number term2) {
+        System.out.println("Adding numbers");
+        return term1.doubleValue() + term2.doubleValue();
+    }
+
+    public Number sum(Object term1, Object term2) {
+        System.out.println("Adding objects");
+        return term1.hashCode() + term2.hashCode();
+    }
+
+    public Number sum(Object term1, Object... term2) {
+        System.out.println("Adding variable arguments: " + term2.length);
+        int result = term1.hashCode();
+        for (Object o : term2) {
+            result += o.hashCode();
+        }
+        return result;
+    }
+
+    public static void main(String[] args) {
+        StaticBinding obj = new StaticBinding();
+
+        obj.sum(2, 3); // "Adding integers" due to auto-boxing from int to Integer
+        obj.sum(Integer.valueOf(2), Integer.valueOf(3)); // "Adding integers" due to exact parameter types
+        obj.sum(2, 0x1); // "Adding integers" due to type promotion from byte to int
+
+        obj.sum((Number) 2, (Number) 3); // "Adding numbers" due to explicit cast to Number
+        obj.sum(2.0d, 3.0d); // "Adding numbers" due to auto-boxing from double to Double
+        obj.sum(Float.valueOf(2), Float.valueOf(3)); // "Adding numbers" due to polimorphism
+
+        obj.sum((Object) 2, (Object) 3); // "Adding objects" due to explicit cast to Object
+        obj.sum(2, "John"); // "Adding objects" due to polimorphism
+
+        obj.sum(new Object(), new Object(), new Object()); // "Adding variable arguments 2"
+        obj.sum(new Object(), new Object[]{new Object()}); // "Adding variable arguments 1"
+    }
+}

core-java-modules/core-java-networking-2/README.md

@@ -13,4 +13,5 @@ This module contains articles about networking in Java
 - [Download a File from an URL in Java](https://www.baeldung.com/java-download-file)
 - [Handling java.net.ConnectException](https://www.baeldung.com/java-net-connectexception)
 - [Getting MAC addresses in Java](https://www.baeldung.com/java-mac-address)
+- [Sending Emails with Attachments in Java](https://www.baeldung.com/java-send-emails-attachments)
 - [[<-- Prev]](/core-java-modules/core-java-networking)