Merge remote-tracking branch 'eugenp/master'

README.md

@@ -2,41 +2,22 @@
 The "REST with Spring" Classes
 ==============================
 
-Here's the Master Class of REST With Spring (price changes permanently next Friday): <br/>
+Here's the Master Class of REST With Spring (along with the newly announced Boot 2 material): <br/>
-**[>> THE REST WITH SPRING MASTER CLASS](http://www.baeldung.com/rest-with-spring-course?utm_source=github&utm_medium=social&utm_content=tutorials&utm_campaign=rws#master-class)**
+**[>> THE REST WITH SPRING - MASTER CLASS](http://www.baeldung.com/rest-with-spring-course?utm_source=github&utm_medium=social&utm_content=tutorials&utm_campaign=rws#master-class)**
 
 And here's the Master Class of Learn Spring Security: <br/>
-**[>> LEARN SPRING SECURITY MASTER CLASS](http://www.baeldung.com/learn-spring-security-course?utm_source=github&utm_medium=social&utm_content=tutorials&utm_campaign=lss#master-class)**
+**[>> LEARN SPRING SECURITY - MASTER CLASS](http://www.baeldung.com/learn-spring-security-course?utm_source=github&utm_medium=social&utm_content=tutorials&utm_campaign=lss#master-class)**
 
 
 
-Spring Tutorials
+Java and Spring Tutorials
 ================
 
-This project is **a collection of small and focused tutorials** each covering a single and well defined area of development. 
+This project is **a collection of small and focused tutorials** - each covering a single and well defined area of development in the Java ecosystem. 
-Most of the tutorial projects are focused on the `Spring Framework` (and `Spring Security`).  
+A strong focus of these is, of course, the Spring Framework - Spring, Spring Boot and Spring Securiyt. 
 In additional to Spring, the following technologies are in focus: `core Java`, `Jackson`, `HttpClient`, `Guava`. 
 
+
 Building the project
 ====================
 To do the full build, do: `mvn install -Pdefault -Dgib.enabled=false`
-
-
-Working with the code in Eclipse
-================================
-Any IDE can be used to work with the projects, but if you're using Eclipse, consider the following. 
-
-- import the included **formatter** in Eclipse: 
-`https://github.com/eugenp/tutorials/tree/master/eclipse`
-
-
-CI - Jenkins
-================================
-This tutorials project is being built **[>> HERE](https://rest-security.ci.cloudbees.com/job/tutorials-unit/)**
-
-### Relevant Articles: 
-================================
-
-- [Apache Maven Standard Directory Layout](http://www.baeldung.com/maven-directory-structure)
-- [Apache Maven Tutorial](http://www.baeldung.com/maven)
-- [Designing a User Friendly Java Library](http://www.baeldung.com/design-a-user-friendly-java-library)

algorithms/src/main/java/com/baeldung/algorithms/kthlargest/FindKthLargest.java

@@ -98,7 +98,7 @@ public class FindKthLargest {
 
     private int randomPartition(Integer arr[], int left, int right) {
         int n = right - left + 1;
-        int pivot = (int) (Math.random()) % n;
+        int pivot = (int) (Math.random() * n);
         swap(arr, left + pivot, right);
         return partition(arr, left, right);
     }

algorithms/src/main/java/com/baeldung/algorithms/quicksort/QuickSort.java

@@ -0,0 +1,39 @@
+package com.baeldung.algorithms.quicksort;
+
+public class QuickSort {
+
+    public static void quickSort(int arr[], int begin, int end)
+    {
+        if (begin < end) {
+            int partitionIndex = partition(arr, begin, end);
+
+            // Recursively sort elements of the 2 sub-arrays
+            quickSort(arr, begin, partitionIndex-1);
+            quickSort(arr, partitionIndex+1, end);
+        }
+    }
+
+    private static int partition(int arr[], int begin, int end)
+    {
+        int pivot = arr[end];
+        int i = (begin-1);
+
+        for (int j=begin; j<end; j++)
+        {
+            if (arr[j] <= pivot) {
+                i++;
+
+                int swapTemp = arr[i];
+                arr[i] = arr[j];
+                arr[j] = swapTemp;
+            }
+        }
+
+        int swapTemp = arr[i+1];
+        arr[i+1] = arr[end];
+        arr[end] = swapTemp;
+
+        return i+1;
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/quicksort/ThreeWayQuickSort.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.quicksort;
+
+public class ThreeWayQuickSort {
+
+    public static void threeWayQuickSort(int[] a, int begin, int end)
+    {
+        if (end <= begin) return;
+
+        // partition
+        int i = begin;
+        int less = begin;
+        int greater = end;
+
+        while (i <= greater){
+            if (a[i] < a[less]) {
+                int tmp = a[i];
+                a[i] = a[less];
+                a[less] = tmp;
+
+                i++;
+                less++;
+            }
+            else if (a[less] < a[i])	{
+                int tmp = a[i];
+                a[i] = a[greater];
+                a[greater] = tmp;
+
+                greater--;
+            }
+            else {
+                i++;
+            }
+        }
+
+        threeWayQuickSort(a, begin, less - 1);
+        threeWayQuickSort(a, greater + 1, end);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/quicksort/QuickSortUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.algorithms.quicksort;
+
+import com.baeldung.algorithms.quicksort.QuickSort;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class QuickSortUnitTest {
+
+    @Test
+    public void givenIntegerArray_whenSortedWithQuickSort_thenGetSortedArray() {
+        int[] actual = { 9, 5, 1, 0, 6, 2, 3, 4, 7, 8 };
+        int[] expected = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+        QuickSort.quickSort(actual, 0, actual.length-1);
+        Assert.assertArrayEquals(expected, actual);
+    }
+
+}

algorithms/src/test/java/com/baeldung/algorithms/quicksort/ThreeWayQuickSortUnitTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.algorithms.quicksort;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class ThreeWayQuickSortUnitTest {
+
+    @Test
+    public void givenIntegerArray_whenSortedWithThreeWayQuickSort_thenGetSortedArray() {
+        int[] actual = { 3, 5, 5, 5, 3, 7, 7, 3, 5, 5, 7, 3, 3 };
+        int[] expected = { 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 7, 7, 7 };
+        ThreeWayQuickSort.threeWayQuickSort(actual, 0, actual.length-1);
+        Assert.assertArrayEquals(expected, actual);
+    }
+}

apache-geode/pom.xml

@@ -0,0 +1,46 @@
+<?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>
+
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-geode</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+    
+    <properties>
+        <geode.core>1.6.0</geode.core>
+    </properties>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.geode</groupId>
+            <artifactId>geode-core</artifactId>
+            <version>${geode.core}</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>RELEASE</version>
+        </dependency>
+    </dependencies>
+    
+</project>

apache-geode/src/main/java/com/baeldung/geode/Customer.java

@@ -0,0 +1,78 @@
+package com.baeldung.geode;
+
+import java.io.Serializable;
+import java.util.Objects;
+
+public class Customer implements Serializable {
+
+    private static final long serialVersionUID = -7482516011038799900L;
+
+    private CustomerKey key;
+    private String firstName;
+    private String lastName;
+    private Integer age;
+
+    public Customer() {
+    }
+
+    public Customer(String firstName, String lastName, int age) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.age = age;
+    }
+
+    public Customer(CustomerKey key, String firstName, String lastName, int age) {
+        this(firstName, lastName, age);
+        this.key = key;
+    }
+
+    // setters and getters
+
+    public static long getSerialVersionUID() {
+        return serialVersionUID;
+    }
+
+    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;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "Customer{" + "firstName='" + firstName + '\'' + ", lastName='" + lastName + '\'' + ", age=" + age + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Customer customer = (Customer) o;
+        return Objects.equals(firstName, customer.firstName) && Objects.equals(lastName, customer.lastName) && Objects.equals(age, customer.age);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(firstName, lastName, age);
+    }
+}

apache-geode/src/main/java/com/baeldung/geode/CustomerKey.java

@@ -0,0 +1,57 @@
+package com.baeldung.geode;
+
+import java.io.Serializable;
+
+public class CustomerKey implements Serializable {
+
+    private static final long serialVersionUID = -3529253035303792458L;
+    private long id;
+    private String country;
+
+    public CustomerKey(long id) {
+        this.id = id;
+        this.country = "USA";
+    }
+
+    public CustomerKey(long id, String country) {
+        this.id = id;
+        this.country = country;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getCountry() {
+        return country;
+    }
+
+    public void setCountry(String country) {
+        this.country = country;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+
+        CustomerKey that = (CustomerKey) o;
+
+        if (id != that.id)
+            return false;
+        return country != null ? country.equals(that.country) : that.country == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = (int) (id ^ (id >>> 32));
+        result = 31 * result + (country != null ? country.hashCode() : 0);
+        return result;
+    }
+}

apache-geode/src/main/java/com/baeldung/geode/functions/UpperCaseNames.java

@@ -0,0 +1,34 @@
+package com.baeldung.geode.functions;
+
+import com.baeldung.geode.Customer;
+import com.baeldung.geode.CustomerKey;
+import org.apache.geode.cache.Region;
+import org.apache.geode.cache.execute.Function;
+import org.apache.geode.cache.execute.FunctionContext;
+import org.apache.geode.cache.execute.RegionFunctionContext;
+
+import java.util.Map;
+
+public class UpperCaseNames implements Function<Boolean> {
+    private static final long serialVersionUID = -8946294032165677602L;
+
+    @Override
+    public void execute(FunctionContext<Boolean> context) {
+        RegionFunctionContext regionContext = (RegionFunctionContext) context;
+        Region<CustomerKey, Customer> region = regionContext.getDataSet();
+
+        for (Map.Entry<CustomerKey, Customer> entry : region.entrySet()) {
+            Customer customer = entry.getValue();
+            customer.setFirstName(customer.getFirstName()
+                .toUpperCase());
+        }
+
+        context.getResultSender()
+            .lastResult(true);
+    }
+
+    @Override
+    public String getId() {
+        return getClass().getName();
+    }
+}

apache-geode/src/test/java/com/baeldung/geode/GeodeSamplesIntegrationTest.java

@@ -0,0 +1,110 @@
+package com.baeldung.geode;
+
+import com.baeldung.geode.functions.UpperCaseNames;
+import org.apache.geode.cache.Region;
+import org.apache.geode.cache.client.ClientCache;
+import org.apache.geode.cache.client.ClientCacheFactory;
+import org.apache.geode.cache.client.ClientRegionShortcut;
+import org.apache.geode.cache.execute.Execution;
+import org.apache.geode.cache.execute.FunctionService;
+import org.apache.geode.cache.query.*;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
+
+public class GeodeSamplesIntegrationTest {
+
+    ClientCache cache = null;
+    Region<String, String> region = null;
+    Region<Integer, Customer> queryRegion = null;
+    Region<CustomerKey, Customer> customerRegion = null;
+
+    @Before
+    public void connect() {
+        this.cache = new ClientCacheFactory().addPoolLocator("localhost", 10334)
+            .create();
+        this.region = this.cache.<String, String> createClientRegionFactory(ClientRegionShortcut.CACHING_PROXY)
+            .create("baeldung");
+        this.customerRegion = this.cache.<CustomerKey, Customer> createClientRegionFactory(ClientRegionShortcut.CACHING_PROXY)
+            .create("baeldung-customers");
+    }
+
+    @After
+    public void cleanup() {
+        this.cache.close();
+    }
+
+    @Test
+    public void whenSendMessageToRegion_thenMessageSavedSuccessfully() {
+
+        this.region.put("1", "Hello");
+        this.region.put("2", "Baeldung");
+
+        assertEquals("Hello", region.get("1"));
+        assertEquals("Baeldung", region.get("2"));
+
+    }
+
+    @Test
+    public void whenPutMultipleValuesAtOnce_thenValuesSavedSuccessfully() {
+
+        Supplier<Stream<String>> keys = () -> Stream.of("A", "B", "C", "D", "E");
+        Map<String, String> values = keys.get()
+            .collect(Collectors.toMap(Function.identity(), String::toLowerCase));
+
+        this.region.putAll(values);
+
+        keys.get()
+            .forEach(k -> assertEquals(k.toLowerCase(), this.region.get(k)));
+
+    }
+
+    @Test
+    public void whenPutCustomKey_thenValuesSavedSuccessfully() {
+        CustomerKey key = new CustomerKey(123);
+        Customer customer = new Customer(key, "William", "Russell", 35);
+
+        Map<CustomerKey, Customer> customerInfo = new HashMap<>();
+        customerInfo.put(key, customer);
+
+        this.customerRegion.putAll(customerInfo);
+
+        Customer storedCustomer = this.customerRegion.get(key);
+        assertEquals("William", storedCustomer.getFirstName());
+        assertEquals("Russell", storedCustomer.getLastName());
+
+    }
+
+    @Test
+    public void whenFindACustomerUsingOQL_thenCorrectCustomerObject() throws NameResolutionException, TypeMismatchException, QueryInvocationTargetException, FunctionDomainException {
+
+        Map<CustomerKey, Customer> data = new HashMap<>();
+        data.put(new CustomerKey(1), new Customer("Gheorge", "Manuc", 36));
+        data.put(new CustomerKey(2), new Customer("Allan", "McDowell", 43));
+        this.customerRegion.putAll(data);
+
+        QueryService queryService = this.cache.getQueryService();
+        String query = "select * from /baeldung-customers c where c.firstName = 'Allan'";
+        SelectResults<Customer> queryResults = (SelectResults<Customer>) queryService.newQuery(query)
+            .execute();
+        assertEquals(1, queryResults.size());
+
+    }
+
+    @Test
+    public void whenExecuteUppercaseNames_thenCustomerNamesAreUppercased() {
+        Execution execution = FunctionService.onRegion(this.customerRegion);
+        execution.execute(UpperCaseNames.class.getName());
+        Customer customer = this.customerRegion.get(new CustomerKey(1));
+        assertEquals("GHEORGE", customer.getFirstName());
+    }
+}

core-java-8/src/test/java/com/baeldung/java8/Java8SortUnitTest.java

@@ -1,16 +1,18 @@
 package com.baeldung.java8;
 
-import com.baeldung.java8.entity.Human;
+import static org.hamcrest.Matchers.equalTo;
-import com.google.common.collect.Lists;
-import com.google.common.primitives.Ints;
-import org.junit.Assert;
-import org.junit.Test;
 
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
+import java.util.stream.Collectors;
 
-import static org.hamcrest.Matchers.equalTo;
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.java8.entity.Human;
+import com.google.common.collect.Lists;
+import com.google.common.primitives.Ints;
 
 public class Java8SortUnitTest {
 
@@ -111,5 +113,22 @@ public class Java8SortUnitTest {
         humans.sort(Comparator.comparing(Human::getName));
         Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
     }
+    
+    @Test
+    public final void givenStreamNaturalOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
+        final List<String> letters = Lists.newArrayList("B", "A", "C");
+        
+        final List<String> sortedLetters = letters.stream().sorted().collect(Collectors.toList());
+        Assert.assertThat(sortedLetters.get(0), equalTo("A"));
+    }
 
+    @Test
+    public final void givenStreamCustomOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
+        
+        final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
+        final Comparator<Human> nameComparator = (h1, h2) -> h1.getName().compareTo(h2.getName());
+        
+        final List<Human> sortedHumans = humans.stream().sorted(nameComparator).collect(Collectors.toList());
+        Assert.assertThat(sortedHumans.get(0), equalTo(new Human("Jack", 12)));
+    }
 }

core-java-8/src/test/java/com/baeldung/stream/conditional/StreamForEachIfElseUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.stream.conditional;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class StreamForEachIfElseUnitTest {
+
+    @Test
+    public final void givenIntegerStream_whenCheckingIntegerParityWithIfElse_thenEnsureCorrectParity() {
+        List<Integer> ints = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+
+        ints.stream()
+            .forEach(i -> {
+                if (i.intValue() % 2 == 0) {
+                    Assert.assertTrue(i.intValue() + " is not even", i.intValue() % 2 == 0);
+                } else {
+                    Assert.assertTrue(i.intValue() + " is not odd", i.intValue() % 2 != 0);
+                }
+            });
+
+    }
+
+    @Test
+    public final void givenIntegerStream_whenCheckingIntegerParityWithStreamFilter_thenEnsureCorrectParity() {
+        List<Integer> ints = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+
+        Stream<Integer> evenIntegers = ints.stream()
+            .filter(i -> i.intValue() % 2 == 0);
+        Stream<Integer> oddIntegers = ints.stream()
+            .filter(i -> i.intValue() % 2 != 0);
+
+        evenIntegers.forEach(i -> Assert.assertTrue(i.intValue() + " is not even", i.intValue() % 2 == 0));
+        oddIntegers.forEach(i -> Assert.assertTrue(i.intValue() + " is not odd", i.intValue() % 2 != 0));
+
+    }
+
+}

core-java/README.md

@@ -25,7 +25,6 @@
 - [The Traveling Salesman Problem in Java](http://www.baeldung.com/java-simulated-annealing-for-traveling-salesman)
 - [How to Create an Executable JAR with Maven](http://www.baeldung.com/executable-jar-with-maven)
 - [How to Design a Genetic Algorithm in Java](http://www.baeldung.com/java-genetic-algorithm)
-- [Spring Security – Cache Control Headers](http://www.baeldung.com/spring-security-cache-control-headers)
 - [Basic Introduction to JMX](http://www.baeldung.com/java-management-extensions)
 - [AWS Lambda With Java](http://www.baeldung.com/java-aws-lambda)
 - [Introduction to Nashorn](http://www.baeldung.com/java-nashorn)

core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/Person.java

@@ -0,0 +1,9 @@
+package com.baeldung.memoryleaks.equalshashcode;
+
+public class Person {
+    public String name;
+     
+    public Person(String name) {
+        this.name = name;
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/PersonOptimized.java

@@ -0,0 +1,25 @@
+package com.baeldung.memoryleaks.equalshashcode;
+
+public class PersonOptimized {
+    public String name;
+     
+    public PersonOptimized(String name) {
+        this.name = name;
+    }
+     
+    @Override
+    public boolean equals(Object o) {
+        if (o == this) return true;
+        if (!(o instanceof PersonOptimized)) {
+            return false;
+        }
+        PersonOptimized person = (PersonOptimized) o;
+        return person.name.equals(name);
+    }
+     
+    @Override
+    public int hashCode() {
+        int result = 17;
+        result = 31 * result + name.hashCode();
+        return result;
+    }}

core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObject.java

@@ -0,0 +1,32 @@
+package com.baeldung.memoryleaks.finalize;
+
+import java.nio.charset.Charset;
+import java.util.Random;
+
+public class BulkyObject {
+    private String data[];
+    
+    public BulkyObject() {
+        data = new String[1000000];
+        
+        for(int i=0; i<1000000; i++) {
+            data[i] = getRandomString();
+        }
+    }
+    
+    private String getRandomString() {
+        byte[] array = new byte[1000];
+        new Random().nextBytes(array);
+        return new String(array, Charset.forName("UTF-8"));
+    }
+    
+    @Override
+    public void finalize() {
+        try {
+            Thread.sleep(100);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        System.out.println("Finalizer called");
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObjectOptimized.java

@@ -0,0 +1,22 @@
+package com.baeldung.memoryleaks.finalize;
+
+import java.nio.charset.Charset;
+import java.util.Random;
+
+public class BulkyObjectOptimized {
+    private String data[];
+    
+    public BulkyObjectOptimized() {
+        data = new String[1000000];
+        
+        for(int i=0; i<1000000; i++) {
+            data[i] = getRandomString();
+        }
+    }
+    
+    private String getRandomString() {
+        byte[] array = new byte[1000];
+        new Random().nextBytes(array);
+        return new String(array, Charset.forName("UTF-8"));
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/innerclass/BulkyObject.java

@@ -0,0 +1,22 @@
+package com.baeldung.memoryleaks.innerclass;
+
+import java.nio.charset.Charset;
+import java.util.Random;
+
+public class BulkyObject {
+    private String data[];
+    
+    public BulkyObject() {
+        data = new String[1000000];
+        
+        for(int i=0; i<1000000; i++) {
+            data[i] = getRandomString();
+        }
+    }
+    
+    private String getRandomString() {
+        byte[] array = new byte[1000];
+        new Random().nextBytes(array);
+        return new String(array, Charset.forName("UTF-8"));
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassDriver.java

@@ -0,0 +1,17 @@
+package com.baeldung.memoryleaks.innerclass;
+
+public class InnerClassDriver {
+    public static InnerClassWrapper.SimpleInnerClass getSimpleInnerClassObj() {
+        return new InnerClassWrapper().new SimpleInnerClass();
+    }
+    
+    public static void main2(String[] args) {
+        InnerClassWrapper.SimpleInnerClass simpleInnerClassObj = getSimpleInnerClassObj();
+        System.out.println("Debug point");
+    }
+    
+    public static void main(String[] args) {
+        StaticNestedClassWrapper.StaticNestedClass simpleInnerClassObj = new StaticNestedClassWrapper.StaticNestedClass();
+        System.out.println("Debug point");
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassWrapper.java

@@ -0,0 +1,10 @@
+package com.baeldung.memoryleaks.innerclass;
+
+
+public class InnerClassWrapper {
+    private BulkyObject bulkyObject = new BulkyObject();
+    
+    public class SimpleInnerClass {
+        
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/innerclass/StaticNestedClassWrapper.java

@@ -0,0 +1,10 @@
+package com.baeldung.memoryleaks.innerclass;
+
+
+public class StaticNestedClassWrapper {
+    private BulkyObject bulkyObject = new BulkyObject();
+    
+    public static class StaticNestedClass {
+        
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/InternedString.java

@@ -0,0 +1,17 @@
+package com.baeldung.memoryleaks.internedstrings;
+
+public class InternedString {
+    private static final String FILEPATH = "C:\\bigstring.txt";
+    
+    public void readString() {
+        String s1 = ReadStringFromFileUtil.read(FILEPATH).intern();
+        String s2 = ReadStringFromFileUtil.read(FILEPATH).intern();
+
+        if (s1 == s2) {
+            System.out.println("Both the strings objects are same");
+        }
+        else {
+            System.out.println("Both the strings objects are different");
+        }
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/ReadStringFromFileUtil.java

@@ -0,0 +1,34 @@
+package com.baeldung.memoryleaks.internedstrings;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+public class ReadStringFromFileUtil {
+
+    public static String read(String fileName) {
+        BufferedReader br = null;
+        try {
+            br = new BufferedReader(new FileReader(fileName));
+            StringBuilder sb = new StringBuilder();
+            String line = br.readLine();
+
+            while (line != null) {
+                sb.append(line);
+                sb.append("\n");
+                line = br.readLine();
+            }
+            return sb.toString();
+        } catch (IOException e) {
+            e.printStackTrace();
+        } finally {
+            try {
+                br.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+        return null;
+    }
+
+}

core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/StringObject.java

@@ -0,0 +1,17 @@
+package com.baeldung.memoryleaks.internedstrings;
+
+public class StringObject {
+    private static final String FILEPATH = "C:\\bigstring.txt";
+    
+    public void readString() {
+        String s1 = ReadStringFromFileUtil.read(FILEPATH);
+        String s2 = ReadStringFromFileUtil.read(FILEPATH);
+
+        if (s1 == s2) {
+            System.out.println("Both the strings objects are same");
+        }
+        else {
+            System.out.println("Both the strings objects are different");
+        }
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsDemo.java

@@ -0,0 +1,21 @@
+package com.baeldung.memoryleaks.staticfields;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class NonStaticFieldsDemo {
+    public List<Double> list = new ArrayList<>();
+ 
+    public void populateList() {
+        for (int i = 0; i < 10000000; i++) {
+            list.add(Math.random());
+        }
+        System.out.println("Debug Point 2");
+    }
+ 
+    public static void main(String[] args) {
+        System.out.println("Debug Point 1");
+        new NonStaticFieldsDemo().populateList();
+        System.out.println("Debug Point 3");
+    }
+}

core-java/src/main/java/com/baeldung/memoryleaks/staticfields/StaticFieldsDemo.java

@@ -0,0 +1,21 @@
+package com.baeldung.memoryleaks.staticfields;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class StaticFieldsDemo {
+    public static List<Double> list = new ArrayList<>();
+ 
+    public void populateList() {
+        for (int i = 0; i < 10000000; i++) {
+            list.add(Math.random());
+        }
+        System.out.println("Debug Point 2");
+    }
+ 
+    public static void main(String[] args) {
+        System.out.println("Debug Point 1");
+        new StaticFieldsDemo().populateList();
+        System.out.println("Debug Point 3");
+    }
+}

core-java/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java

@@ -0,0 +1,8 @@
+package com.baeldung.nth.root.calculator;
+
+public class NthRootCalculator
+{
+    public Double calculate(Double base, Double n) {
+        return Math.pow(Math.E, Math.log(base)/n);
+    }
+}

core-java/src/main/java/com/baeldung/nth/root/main/Main.java

@@ -0,0 +1,13 @@
+package com.baeldung.nth.root.main;
+
+import com.baeldung.nth.root.calculator.NthRootCalculator;
+
+public class Main {
+    public static void main(String[] args) {
+        NthRootCalculator calculator = new NthRootCalculator();
+        Double base = Double.parseDouble(args[0]);
+        Double n = Double.parseDouble(args[1]);
+        Double result = calculator.calculate(base, n);
+        System.out.println("The " + n + " root of " + base + " equals to " + result + ".");
+    }
+}

core-java/src/test/java/com/baeldung/memoryleaks/equalshashcode/PersonMemoryLeakUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.memoryleaks.equalshashcode;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Ignore;
+import org.junit.Test;
+
+public class PersonMemoryLeakUnitTest {
+    @Test
+    @Ignore // Test deliberately ignored as memory leak tests consume lots of resources
+    public void givenMap_whenEqualsAndHashCodeNotOverridden_thenMemoryLeak() {
+        Map<Person, Integer> map = new HashMap<Person, Integer>();
+        for(int i=0; i<10000000; i++) {
+            map.put(new Person("jon"), 1);
+        }
+        assertTrue(map.size() > 1);
+        System.out.print("Debug Point - VisuaLVM");
+    }
+    
+    @Test
+    @Ignore // Test deliberately ignored as memory leak tests consume lots of resources
+    public void givenMap_whenEqualsAndHashCodeOverridden_thenNoMemoryLeak() {
+        Map<PersonOptimized, Integer> map = new HashMap<PersonOptimized, Integer>();
+        for(int i=0; i<10000; i++) {
+            map.put(new PersonOptimized("jon"), 1);
+        }
+        assertTrue(map.size() == 1);
+        System.out.print("Debug Point - VisuaLVM");
+    }
+}