Merge branch 'master' into BAEL-3521

core-java-modules/core-java-collections-list-3/README.md

@@ -9,4 +9,5 @@ This module contains articles about the Java List collection
 - [List of Primitive Integer Values in Java](https://www.baeldung.com/java-list-primitive-int)
 - [Performance Comparison of Primitive Lists in Java](https://www.baeldung.com/java-list-primitive-performance)
 - [Filtering a Java Collection by a List](https://www.baeldung.com/java-filter-collection-by-list)
+- [How to Count Duplicate Elements in Arraylist](https://www.baeldung.com/java-count-duplicate-elements-arraylist)
 - [[<-- Prev]](/core-java-modules/core-java-collections-list-2)

core-java-modules/core-java-concurrency-advanced-3/pom.xml

@@ -27,6 +27,16 @@
 
     <build>
         <finalName>core-java-concurrency-advanced-3</finalName>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
         <resources>
             <resource>
                 <directory>src/main/resources</directory>
@@ -37,6 +47,8 @@
 
     <properties>
         <assertj.version>3.14.0</assertj.version>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
 
 </project>

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/CollectionsConcurrencyIssues.java

@@ -0,0 +1,53 @@
+package com.baeldung.commonissues;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class CollectionsConcurrencyIssues {
+
+    private void putIfAbsentList_NonAtomicOperation_ProneToConcurrencyIssues() {
+        List<String> list = Collections.synchronizedList(new ArrayList<>());
+        if (!list.contains("foo")) {
+            list.add("foo");
+        }
+    }
+
+    private void putIfAbsentList_AtomicOperation_ThreadSafe() {
+        List<String> list = Collections.synchronizedList(new ArrayList<>());
+        synchronized (list) {
+            if (!list.contains("foo")) {
+                list.add("foo");
+            }
+        }
+    }
+
+    private void putIfAbsentMap_NonAtomicOperation_ProneToConcurrencyIssues() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        if (!map.containsKey("foo")) {
+            map.put("foo", "bar");
+        }
+    }
+
+    private void putIfAbsentMap_AtomicOperation_BetterApproach() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        synchronized (map) {
+            if (!map.containsKey("foo")) {
+                map.put("foo", "bar");
+            }
+        }
+    }
+
+    private void putIfAbsentMap_AtomicOperation_BestApproach() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        map.putIfAbsent("foo", "bar");
+    }
+
+    private void computeIfAbsentMap_AtomicOperation() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        map.computeIfAbsent("foo", key -> key + "bar");
+    }
+
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/Counter.java

@@ -0,0 +1,13 @@
+package com.baeldung.commonissues;
+
+class Counter {
+    private int counter = 0;
+
+    public void increment() {
+        counter++;
+    }
+
+    public int getValue() {
+        return counter;
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/DeadlockExample.java

@@ -0,0 +1,42 @@
+package com.baeldung.commonissues;
+
+public class DeadlockExample {
+
+    public static Object lock1 = new Object();
+    public static Object lock2 = new Object();
+
+    public static void main(String args[]) {
+        Thread threadA = new Thread(() -> {
+            synchronized (lock1) {
+                System.out.println("ThreadA: Holding lock 1...");
+                sleep();
+                System.out.println("ThreadA: Waiting for lock 2...");
+
+                synchronized (lock2) {
+                    System.out.println("ThreadA: Holding lock 1 & 2...");
+                }
+            }
+        });
+        Thread threadB = new Thread(() -> {
+            synchronized (lock2) {
+                System.out.println("ThreadB: Holding lock 2...");
+                sleep();
+                System.out.println("ThreadB: Waiting for lock 1...");
+
+                synchronized (lock1) {
+                    System.out.println("ThreadB: Holding lock 1 & 2...");
+                }
+            }
+        });
+        threadA.start();
+        threadB.start();
+    }
+
+    private static void sleep() {
+        try {
+            Thread.sleep(100);
+        } catch (InterruptedException e) {
+            throw new RuntimeException();
+        }
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/SimpleDateFormatThreadUnsafetyExample.java

@@ -0,0 +1,35 @@
+package com.baeldung.commonissues;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class SimpleDateFormatThreadUnsafetyExample {
+
+    private static SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+
+    public static void main(String[] args) {
+        String dateStr = "2019-10-29T11:12:21";
+
+        ExecutorService executorService = Executors.newFixedThreadPool(10);
+
+        for (int i = 0; i < 20; i++) {
+            executorService.submit(() -> parseDate(dateStr));
+        }
+
+        executorService.shutdown();
+    }
+
+    private static void parseDate(String dateStr) {
+        try {
+            Date date = simpleDateFormat.parse(dateStr);
+            System.out.println("Successfully Parsed Date " + date);
+        } catch (ParseException e) {
+            System.out.println("ParseError " + e.getMessage());
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/SynchronizedCounter.java

@@ -0,0 +1,13 @@
+package com.baeldung.commonissues;
+
+class SynchronizedCounter {
+    private int counter = 0;
+
+    public synchronized void increment() {
+        counter++;
+    }
+
+    public synchronized int getValue() {
+        return counter;
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/SynchronizedVolatileCounter.java

@@ -0,0 +1,13 @@
+package com.baeldung.commonissues;
+
+class SynchronizedVolatileCounter {
+    private volatile int counter = 0;
+
+    public synchronized void increment() {
+        counter++;
+    }
+
+    public int getValue() {
+        return counter;
+    }
+}

core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/threadsafety/CounterUnitTest.java

@@ -18,8 +18,11 @@ public class CounterUnitTest {
         Counter counter = new Counter();
         Future<Integer> future1 = (Future<Integer>) executorService.submit(new CounterCallable(counter));
         Future<Integer> future2 = (Future<Integer>) executorService.submit(new CounterCallable(counter));
-        
-        assertThat(future1.get()).isEqualTo(1);
-        assertThat(future2.get()).isEqualTo(2);
+
+        // Just to make sure both are completed
+        future1.get();
+        future2.get();
+
+        assertThat(counter.getCounter()).isEqualTo(2);
     }
 }

core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/threadsafety/ExtrinsicLockCounterUnitTest.java

@@ -18,8 +18,11 @@ public class ExtrinsicLockCounterUnitTest {
         ExtrinsicLockCounter counter = new ExtrinsicLockCounter();
         Future<Integer> future1 = (Future<Integer>) executorService.submit(new ExtrinsicLockCounterCallable(counter));
         Future<Integer> future2 = (Future<Integer>) executorService.submit(new ExtrinsicLockCounterCallable(counter));
-        
-        assertThat(future1.get()).isEqualTo(1);
-        assertThat(future2.get()).isEqualTo(2);
+
+        // Just to make sure both are completed
+        future1.get();
+        future2.get();
+
+        assertThat(counter.getCounter()).isEqualTo(2);
     }
 }

core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/threadsafety/ReentrantLockCounterUnitTest.java

@@ -11,15 +11,18 @@ import java.util.concurrent.Future;
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class ReentrantLockCounterUnitTest {
-    
+
     @Test
     public void whenCalledIncrementCounter_thenCorrect() throws Exception {
         ExecutorService executorService = Executors.newFixedThreadPool(2);
         ReentrantLockCounter counter = new ReentrantLockCounter();
         Future<Integer> future1 = (Future<Integer>) executorService.submit(new ReentrantLockCounterCallable(counter));
         Future<Integer> future2 = (Future<Integer>) executorService.submit(new ReentrantLockCounterCallable(counter));
-        
-        assertThat(future1.get()).isEqualTo(1);
-        assertThat(future2.get()).isEqualTo(2);
+
+        // Just to make sure both are completed
+        future1.get();
+        future2.get();
+
+        assertThat(counter.getCounter()).isEqualTo(2);
     }
 }

core-java-modules/core-java-concurrency-basic/src/test/java/com/baeldung/concurrent/threadsafety/ReentrantReadWriteLockCounterUnitTest.java

@@ -11,16 +11,19 @@ import java.util.concurrent.Future;
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class ReentrantReadWriteLockCounterUnitTest {
-    
+
     @Test
     public void whenCalledIncrementCounter_thenCorrect() throws Exception {
         ExecutorService executorService = Executors.newFixedThreadPool(2);
         ReentrantReadWriteLockCounter counter = new ReentrantReadWriteLockCounter();
-        Future<Integer> future1 = (Future<Integer>) executorService.submit(new  ReentranReadWriteLockCounterCallable(counter));
-        Future<Integer> future2 = (Future<Integer>) executorService.submit(new  ReentranReadWriteLockCounterCallable(counter));
+        Future<Integer> future1 = (Future<Integer>) executorService.submit(new ReentranReadWriteLockCounterCallable(counter));
+        Future<Integer> future2 = (Future<Integer>) executorService.submit(new ReentranReadWriteLockCounterCallable(counter));
 
-        assertThat(future2.get()).isEqualTo(2);
-        assertThat(future1.get()).isEqualTo(1);
+        // Just to make sure both are completed
+        future1.get();
+        future2.get();
+
+        assertThat(counter.getCounter()).isEqualTo(2);
     }
-    
+
 }

core-java-modules/core-java-date-operations/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+- [Get the Current Date Prior to Java 8](https://www.baeldung.com/java-get-the-current-date-legacy)
+- [Skipping Weekends While Adding Days to LocalDate in Java 8](https://www.baeldung.com/java-localdate-add-days-skip-weekends)

core-java-modules/core-java-date-operations/pom.xml

@@ -1,17 +1,38 @@
 <?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-date-operations</artifactId>
-    <version>${project.parent.version}</version>
-    <packaging>jar</packaging>
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<artifactId>core-java-date-operations</artifactId>
+	<version>${project.parent.version}</version>
+	<packaging>jar</packaging>
 
-    <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
-        <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../../parent-java</relativePath>
-    </parent>
+	<parent>
+		<groupId>com.baeldung</groupId>
+		<artifactId>parent-java</artifactId>
+		<version>0.0.1-SNAPSHOT</version>
+		<relativePath>../../parent-java</relativePath>
+	</parent>
 
+	<dependencies>
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-lang3</artifactId>
+			<version>${commons-lang3.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>joda-time</groupId>
+			<artifactId>joda-time</artifactId>
+			<version>${joda-time.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>com.darwinsys</groupId>
+			<artifactId>hirondelle-date4j</artifactId>
+			<version>${hirondelle-date4j.version}</version>
+		</dependency>
+	</dependencies>
+	<properties>
+		<joda-time.version>2.10</joda-time.version>
+		<hirondelle-date4j.version>1.5.1</hirondelle-date4j.version>
+	</properties>
 </project>

core-java-modules/core-java-date-operations/src/main/java/com/baeldung/date/comparison/DateComparisonUtils.java

@@ -0,0 +1,55 @@
+package com.baeldung.date.comparison;
+
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.time.ZoneId;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.TimeZone;
+
+import org.apache.commons.lang3.time.DateUtils;
+
+import hirondelle.date4j.DateTime;
+
+public class DateComparisonUtils {
+
+    public static boolean isSameDayUsingLocalDate(Date date1, Date date2) {
+        LocalDate localDate1 = date1.toInstant()
+            .atZone(ZoneId.systemDefault())
+            .toLocalDate();
+        LocalDate localDate2 = date2.toInstant()
+            .atZone(ZoneId.systemDefault())
+            .toLocalDate();
+        return localDate1.isEqual(localDate2);
+    }
+
+    public static boolean isSameDayUsingSimpleDateFormat(Date date1, Date date2) {
+        SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
+        return fmt.format(date1)
+            .equals(fmt.format(date2));
+    }
+
+    public static boolean isSameDayUsingCalendar(Date date1, Date date2) {
+        Calendar calendar1 = Calendar.getInstance();
+        calendar1.setTime(date1);
+        Calendar calendar2 = Calendar.getInstance();
+        calendar2.setTime(date2);
+        return calendar1.get(Calendar.YEAR) == calendar2.get(Calendar.YEAR) && calendar1.get(Calendar.MONTH) == calendar2.get(Calendar.MONTH) && calendar1.get(Calendar.DAY_OF_MONTH) == calendar2.get(Calendar.DAY_OF_MONTH);
+    }
+
+    public static boolean isSameDayUsingApacheCommons(Date date1, Date date2) {
+        return DateUtils.isSameDay(date1, date2);
+    }
+
+    public static boolean isSameDayUsingJoda(Date date1, Date date2) {
+        org.joda.time.LocalDate localDate1 = new org.joda.time.LocalDate(date1);
+        org.joda.time.LocalDate localDate2 = new org.joda.time.LocalDate(date2);
+        return localDate1.equals(localDate2);
+    }
+
+    public static boolean isSameDayUsingDate4j(Date date1, Date date2) {
+        DateTime dateObject1 = DateTime.forInstant(date1.getTime(), TimeZone.getDefault());
+        DateTime dateObject2 = DateTime.forInstant(date2.getTime(), TimeZone.getDefault());
+        return dateObject1.isSameDayAs(dateObject2);
+    }
+}

core-java-modules/core-java-date-operations/src/test/java/com/baeldung/date/comparison/DateComparisonUtilsUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.date.comparison;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.util.Date;
+
+import org.junit.Test;
+
+public class DateComparisonUtilsUnitTest {
+
+    private Date day1Morning = toDate(LocalDateTime.of(2019, 10, 19, 6, 30, 40));
+    private Date day1Evening = toDate(LocalDateTime.of(2019, 10, 19, 18, 30, 50));
+    private Date day2Morning = toDate(LocalDateTime.of(2019, 10, 20, 6, 30, 50));
+
+    private Date toDate(LocalDateTime localDateTime) {
+        return Date.from(localDateTime.atZone(ZoneId.systemDefault())
+            .toInstant());
+    }
+
+    @Test
+    public void givenDatesWithDifferentTime_whenIsSameDay_thenReturnsTrue() {
+        assertTrue(DateComparisonUtils.isSameDayUsingLocalDate(day1Morning, day1Evening));
+        assertTrue(DateComparisonUtils.isSameDayUsingSimpleDateFormat(day1Morning, day1Evening));
+        assertTrue(DateComparisonUtils.isSameDayUsingCalendar(day1Morning, day1Evening));
+        assertTrue(DateComparisonUtils.isSameDayUsingApacheCommons(day1Morning, day1Evening));
+        assertTrue(DateComparisonUtils.isSameDayUsingJoda(day1Morning, day1Evening));
+        assertTrue(DateComparisonUtils.isSameDayUsingDate4j(day1Morning, day1Evening));
+    }
+
+    @Test
+    public void givenDates_whenIsDifferentDay_thenReturnsFalse() {
+        assertFalse(DateComparisonUtils.isSameDayUsingLocalDate(day1Morning, day2Morning));
+        assertFalse(DateComparisonUtils.isSameDayUsingLocalDate(day1Evening, day2Morning));
+
+        assertFalse(DateComparisonUtils.isSameDayUsingSimpleDateFormat(day1Morning, day2Morning));
+        assertFalse(DateComparisonUtils.isSameDayUsingSimpleDateFormat(day1Evening, day2Morning));
+
+        assertFalse(DateComparisonUtils.isSameDayUsingCalendar(day1Morning, day2Morning));
+        assertFalse(DateComparisonUtils.isSameDayUsingCalendar(day1Evening, day2Morning));
+
+        assertFalse(DateComparisonUtils.isSameDayUsingApacheCommons(day1Morning, day2Morning));
+        assertFalse(DateComparisonUtils.isSameDayUsingApacheCommons(day1Evening, day2Morning));
+
+        assertFalse(DateComparisonUtils.isSameDayUsingJoda(day1Morning, day2Morning));
+        assertFalse(DateComparisonUtils.isSameDayUsingJoda(day1Evening, day2Morning));
+
+        assertFalse(DateComparisonUtils.isSameDayUsingDate4j(day1Morning, day2Morning));
+        assertFalse(DateComparisonUtils.isSameDayUsingDate4j(day1Evening, day2Morning));
+    }
+}

core-java-modules/core-java-date-operations/src/test/java/com/baeldung/datetime/sql/DateUtilsUnitTest.java

@@ -2,18 +2,16 @@ package com.baeldung.datetime.sql;
 
 import static org.junit.Assert.assertEquals;
 
-import org.junit.Test;
-
-import com.baeldung.datetime.sql.DateUtils;
-
 import java.text.ParseException;
-import java.util.Date;
+import java.time.LocalDate;
+
+import org.junit.Test;
 
 public class DateUtilsUnitTest {
 
     @Test
     public void givenCurrentDate_thenTodayIsReturned() {
-        assertEquals(DateUtils.getNow(), new Date());
+        assertEquals(DateUtils.getNow().toLocalDate(), LocalDate.now());
     }
 
     @Test(expected = IllegalArgumentException.class)

core-java-modules/core-java-date-operations/src/test/java/com/baeldung/datetime/sql/TimeUtilsUnitTest.java

@@ -7,15 +7,9 @@ import org.junit.Test;
 import com.baeldung.datetime.sql.TimeUtils;
 
 import java.text.ParseException;
-import java.util.Date;
 
 public class TimeUtilsUnitTest {
 
-    @Test
-    public void givenCurrentTime_thenNowIsReturned() {
-        assertEquals(TimeUtils.getNow(), new Date());
-    }
-
     @Test(expected = IllegalArgumentException.class)
     public void givenTimeAsString_whenPatternIsNotRespected_thenExceptionIsThrown() {
         TimeUtils.getTime("10 11 12");

core-java-modules/core-java-date-operations/src/test/java/com/baeldung/timezone/ModifyDefaultTimezoneUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.timezone;
+
+import org.junit.Test;
+
+import java.util.Calendar;
+import java.util.Date;
+import java.util.TimeZone;
+
+import static org.junit.Assert.assertEquals;
+
+public class ModifyDefaultTimezoneUnitTest {
+
+    @Test
+    public void givenDefaultTimezoneSet_thenDateTimezoneIsCorrect() {
+        TimeZone.setDefault(TimeZone.getTimeZone("Portugal"));
+        Date date = new Date();
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(date);
+        assertEquals(calendar.getTimeZone(), TimeZone.getTimeZone("Portugal"));
+    }
+
+}

core-java-modules/core-java-date-operations/src/test/java/com/baeldung/timezone/ModifyTimezonePropertyUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.timezone;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Calendar;
+import java.util.Date;
+import java.util.TimeZone;
+
+import static org.junit.Assert.assertEquals;
+
+public class ModifyTimezonePropertyUnitTest {
+
+    @Before
+    public void setup() {
+        System.setProperty("user.timezone", "IST");
+        TimeZone.setDefault(null);
+    }
+
+    @After
+    public void teardown() {
+        System.clearProperty("user.timezone");
+    }
+
+    @Test
+    public void givenTimezonePropertySet_thenDateTimezoneIsCorrect() {
+        Date date = new Date();
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(date);
+        assertEquals(calendar.getTimeZone(), TimeZone.getTimeZone("IST"));
+    }
+
+}

core-java-modules/core-java-datetime-java8/README.md

@@ -13,3 +13,4 @@ This module contains articles about the Date and Time API introduced with Java 8
 - [How to Get the Start and the End of a Day using Java](http://www.baeldung.com/java-day-start-end)
 - [Set the Time Zone of a Date in Java](https://www.baeldung.com/java-set-date-time-zone)
 - [Comparing Dates in Java](https://www.baeldung.com/java-comparing-dates)
+- [Generating Random Dates in Java](https://www.baeldung.com/java-random-dates)

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

@@ -17,3 +17,4 @@ This module contains articles about core java exceptions
 - [Common Java Exceptions](https://www.baeldung.com/java-common-exceptions)
 - [Throw Exception in Optional in Java 8](https://www.baeldung.com/java-optional-throw-exception)
 - [How to Find an Exception’s Root Cause in Java](https://www.baeldung.com/java-exception-root-cause)
+- [Is It a Bad Practice to Catch Throwable?](https://www.baeldung.com/java-catch-throwable-bad-practice)

core-java-modules/core-java-io-2/.gitignore

@@ -1,3 +1,5 @@
-# Intellij
-.idea/
-*.iml
+0.*
+
+# Files generated by integration tests
+# *.txt
+/temp

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

@@ -1,4 +1,15 @@
+## Core Java IO
 
-### Relevant Articles:
+This module contains articles about core Java input and output (IO)
 
+### Relevant Articles: 
 - [Create a File in a Specific Directory in Java](https://www.baeldung.com/java-create-file-in-directory)
+- [How to Read a Large File Efficiently with Java](https://www.baeldung.com/java-read-lines-large-file)
+- [Java – Write to File](https://www.baeldung.com/java-write-to-file)
+- [FileNotFoundException in Java](https://www.baeldung.com/java-filenotfound-exception)
+- [Delete the Contents of a File in Java](https://www.baeldung.com/java-delete-file-contents)
+- [List Files in a Directory in Java](https://www.baeldung.com/java-list-directory-files)
+- [Java – Append Data to a File](https://www.baeldung.com/java-append-to-file)
+- [How to Copy a File with Java](https://www.baeldung.com/java-copy-file)
+- [Create a Directory in Java](https://www.baeldung.com/java-create-directory)
+- [[<-- Prev]](/core-java-modules/core-java-io)

core-java-modules/core-java-io-2/pom.xml

@@ -16,57 +16,16 @@
     <dependencies>
         <!-- utils -->
         <dependency>
-            <groupId>net.sourceforge.collections</groupId>
-            <artifactId>collections-generic</artifactId>
-            <version>${collections-generic.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-collections4</artifactId>
-            <version>${commons-collections4.version}</version>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
         </dependency>
+        <!-- utils -->
         <dependency>
             <groupId>commons-io</groupId>
             <artifactId>commons-io</artifactId>
             <version>${commons-io.version}</version>
         </dependency>
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-lang3</artifactId>
-            <version>${commons-lang3.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-math3</artifactId>
-            <version>${commons-math3.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.decimal4j</groupId>
-            <artifactId>decimal4j</artifactId>
-            <version>${decimal4j.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.bouncycastle</groupId>
-            <artifactId>bcprov-jdk15on</artifactId>
-            <version>${bouncycastle.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.unix4j</groupId>
-            <artifactId>unix4j-command</artifactId>
-            <version>${unix4j.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.googlecode.grep4j</groupId>
-            <artifactId>grep4j</artifactId>
-            <version>${grep4j.version}</version>
-        </dependency>
-        <!-- web -->
-        <!-- marshalling -->
-        <dependency>
-            <groupId>com.fasterxml.jackson.core</groupId>
-            <artifactId>jackson-databind</artifactId>
-            <version>${jackson.version}</version>
-        </dependency>
         <!-- logging -->
         <dependency>
             <groupId>log4j</groupId>
@@ -78,12 +37,6 @@
             <artifactId>log4j-over-slf4j</artifactId>
             <version>${org.slf4j.version}</version>
         </dependency>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <version>${lombok.version}</version>
-            <scope>provided</scope>
-        </dependency>
         <!-- test scoped -->
         <dependency>
             <groupId>org.assertj</groupId>
@@ -91,86 +44,6 @@
             <version>${assertj.version}</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>com.jayway.awaitility</groupId>
-            <artifactId>awaitility</artifactId>
-            <version>${avaitility.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>commons-codec</groupId>
-            <artifactId>commons-codec</artifactId>
-            <version>${commons-codec.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.javamoney</groupId>
-            <artifactId>moneta</artifactId>
-            <version>${moneta.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.owasp.esapi</groupId>
-            <artifactId>esapi</artifactId>
-            <version>${esapi.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.sun.messaging.mq</groupId>
-            <artifactId>fscontext</artifactId>
-            <version>${fscontext.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.codepoetics</groupId>
-            <artifactId>protonpack</artifactId>
-            <version>${protonpack.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>one.util</groupId>
-            <artifactId>streamex</artifactId>
-            <version>${streamex.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>io.vavr</groupId>
-            <artifactId>vavr</artifactId>
-            <version>${vavr.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.openjdk.jmh</groupId>
-            <artifactId>jmh-core</artifactId>
-            <version>${jmh-core.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.openjdk.jmh</groupId>
-            <artifactId>jmh-generator-annprocess</artifactId>
-            <version>${jmh-generator-annprocess.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.hsqldb</groupId>
-            <artifactId>hsqldb</artifactId>
-            <version>${hsqldb.version}</version>
-            <scope>runtime</scope>
-        </dependency>
-        <!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
-        <dependency>
-            <groupId>org.asynchttpclient</groupId>
-            <artifactId>async-http-client</artifactId>
-            <version>${async-http-client.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.opencsv</groupId>
-            <artifactId>opencsv</artifactId>
-            <version>${opencsv.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <!-- Mime Type Resolution Libraries -->
-        <dependency>
-            <groupId>org.apache.tika</groupId>
-            <artifactId>tika-core</artifactId>
-            <version>${tika.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>net.sf.jmimemagic</groupId>
-            <artifactId>jmimemagic</artifactId>
-            <version>${jmime-magic.version}</version>
-        </dependency>
     </dependencies>
 
     <build>
@@ -182,22 +55,6 @@
             </resource>
         </resources>
         <plugins>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>exec-maven-plugin</artifactId>
-                <version>${exec-maven-plugin.version}</version>
-                <configuration>
-                    <executable>java</executable>
-                    <mainClass>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</mainClass>
-                    <arguments>
-                        <argument>-Xmx300m</argument>
-                        <argument>-XX:+UseParallelGC</argument>
-                        <argument>-classpath</argument>
-                        <classpath />
-                        <argument>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</argument>
-                    </arguments>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
@@ -210,70 +67,9 @@
         </plugins>
     </build>
 
-    <profiles>
-        <profile>
-            <id>integration</id>
-            <build>
-                <plugins>
-                    <plugin>
-                        <groupId>org.codehaus.mojo</groupId>
-                        <artifactId>exec-maven-plugin</artifactId>
-
-                        <executions>
-                            <execution>
-                                <id>run-benchmarks</id>
-                                <!-- <phase>integration-test</phase> -->
-                                <phase>none</phase>
-                                <goals>
-                                    <goal>exec</goal>
-                                </goals>
-                                <configuration>
-                                    <classpathScope>test</classpathScope>
-                                    <executable>java</executable>
-                                    <arguments>
-                                        <argument>-classpath</argument>
-                                        <classpath />
-                                        <argument>org.openjdk.jmh.Main</argument>
-                                        <argument>.*</argument>
-                                    </arguments>
-                                </configuration>
-                            </execution>
-                        </executions>
-                    </plugin>
-                </plugins>
-            </build>
-        </profile>
-    </profiles>
-
     <properties>
-
-        <!-- util -->
-        <bouncycastle.version>1.55</bouncycastle.version>
-        <commons-codec.version>1.10</commons-codec.version>
-        <commons-math3.version>3.6.1</commons-math3.version>
-        <decimal4j.version>1.0.3</decimal4j.version>
-        <commons-collections4.version>4.1</commons-collections4.version>
-        <collections-generic.version>4.01</collections-generic.version>
-        <unix4j.version>0.4</unix4j.version>
-        <grep4j.version>1.8.7</grep4j.version>
-        <fscontext.version>4.6-b01</fscontext.version>
-        <protonpack.version>1.13</protonpack.version>
-        <streamex.version>0.6.5</streamex.version>
-        <vavr.version>0.9.0</vavr.version>
-        <opencsv.version>4.1</opencsv.version>
-        <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
-        <avaitility.version>1.7.0</avaitility.version>
-
-        <!-- maven plugins -->
         <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
-        <hsqldb.version>2.4.0</hsqldb.version>
-        <esapi.version>2.1.0.1</esapi.version>
-        <jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
-        <async-http-client.version>2.4.5</async-http-client.version>
-        <!-- Mime Type Libraries -->
-        <tika.version>1.18</tika.version>
-        <jmime-magic.version>0.1.5</jmime-magic.version>
     </properties>
 
 </project>

core-java-modules/core-java-io-2/src/main/java/com/baeldung/listfiles/ListFiles.java

@@ -1,4 +1,4 @@
-package com.baeldung.files;
+package com.baeldung.listfiles;
 
 import java.io.File;
 import java.io.IOException;

core-java-modules/core-java-io-2/src/test/java/com/baeldung/appendtofile/AppendToFileManualTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.file;
+package com.baeldung.appendtofile;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -22,9 +22,7 @@ import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
-import com.baeldung.util.StreamUtils;
-
-public class FilesManualTest {
+public class AppendToFileManualTest {
 
     public static final String fileName = "src/main/resources/countries.properties";
 

core-java-modules/core-java-io-2/src/test/java/com/baeldung/appendtofile/StreamUtils.java

@@ -1,11 +1,11 @@
-package com.baeldung.util;
+package com.baeldung.appendtofile;
+
+import org.apache.commons.io.IOUtils;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringWriter;
 
-import org.apache.commons.io.IOUtils;
-
 public class StreamUtils {
 
     public static String getStringFromInputStream(InputStream input) throws IOException {

core-java-modules/core-java-io-2/src/test/java/com/baeldung/createfiles/CreateFilesUnitTest.java

@@ -5,15 +5,27 @@ import org.junit.Test;
 
 import java.io.File;
 import java.io.IOException;
-
+import org.junit.BeforeClass;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 public class CreateFilesUnitTest {
+
+    @BeforeClass
+    public static void clean() {
+        File tempDirectory = new File(System.getProperty("java.io.tmpdir"));
+        File file1 = new File(tempDirectory.getAbsolutePath() + "/testFile.txt");
+        File file2 = new File(tempDirectory, "newFile.txt");
+        File file3 = new File(tempDirectory.getAbsolutePath() + File.separator + "newFile2.txt");
+        file1.delete();
+        file2.delete();
+        file3.delete();
+    }
+
     @Test
     public void givenAnExistingDirectory_whenCreatingAFileWithAbsolutePath_thenFileIsCreated() throws IOException {
         File tempDirectory = new File(System.getProperty("java.io.tmpdir"));
-        File fileWithAbsolutePath = new File(tempDirectory.getAbsolutePath() + "/myDirectory/testFile.txt");
+        File fileWithAbsolutePath = new File(tempDirectory.getAbsolutePath() + "/testFile.txt");
 
         assertFalse(fileWithAbsolutePath.exists());
 
@@ -25,7 +37,7 @@ public class CreateFilesUnitTest {
     @Test
     public void givenAnExistingDirectory_whenCreatingANewDirectoryAndFileWithRelativePath_thenFileIsCreated() throws IOException {
         File tempDirectory = new File(System.getProperty("java.io.tmpdir"));
-        File fileWithRelativePath = new File(tempDirectory, "myDirectory/newFile.txt");
+        File fileWithRelativePath = new File(tempDirectory, "newFile.txt");
 
         assertFalse(fileWithRelativePath.exists());
 
@@ -37,7 +49,7 @@ public class CreateFilesUnitTest {
     @Test
     public void whenCreatingAFileWithFileSeparator_thenFileIsCreated() throws IOException {
         File tempDirectory = new File(System.getProperty("java.io.tmpdir"));
-        File newFile = new File(tempDirectory.getAbsolutePath() + File.separator + "newFile.txt");
+        File newFile = new File(tempDirectory.getAbsolutePath() + File.separator + "newFile2.txt");
 
         assertFalse(newFile.exists());