Merge branch 'master' of github.com:eugenp/tutorials

.travis.yml

@@ -4,7 +4,7 @@ before_install:
   - echo "MAVEN_OPTS='-Xmx2048M -Xss128M -XX:+CMSClassUnloadingEnabled -XX:+UseG1GC -XX:-UseGCOverheadLimit'" > ~/.mavenrc
 
 install: skip
-script: travis_wait 60 mvn -q install -Pdefault-first,default-second
+script: travis_wait 60 mvn -q install -Pdefault-first,default-second -Dgib.enabled=true
 
 sudo: required
 

algorithms-miscellaneous-2/README.md

@@ -17,3 +17,4 @@
 - [Round Up to the Nearest Hundred](https://www.baeldung.com/java-round-up-nearest-hundred)
 - [Calculate Percentage in Java](https://www.baeldung.com/java-calculate-percentage)
 - [Converting Between Byte Arrays and Hexadecimal Strings in Java](https://www.baeldung.com/java-byte-arrays-hex-strings)
+- [Convert Latitude and Longitude to a 2D Point in Java](https://www.baeldung.com/java-convert-latitude-longitude)

core-java-10/README.md

@@ -4,3 +4,4 @@
 - [Java 10 LocalVariable Type-Inference](http://www.baeldung.com/java-10-local-variable-type-inference)
 - [Guide to Java 10](http://www.baeldung.com/java-10-overview)
 - [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
+- [Deep Dive Into the New Java JIT Compiler – Graal](https://www.baeldung.com/graal-java-jit-compiler)

core-java-8/README.md

@@ -33,3 +33,4 @@
 - [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)
 - [Java Primitives versus Objects](https://www.baeldung.com/java-primitives-vs-objects)
 - [How to Use if/else Logic in Java 8 Streams](https://www.baeldung.com/java-8-streams-if-else-logic)
+- [How to Replace Many if Statements in Java](https://www.baeldung.com/java-replace-if-statements)

core-java-arrays/src/main/java/com/baeldung/array/operations/ArrayOperations.java

@@ -4,11 +4,13 @@ import java.lang.reflect.Array;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
+import java.util.LinkedList;
 import java.util.Random;
 import java.util.Set;
 import java.util.function.Function;
 import java.util.function.IntPredicate;
 import java.util.function.Predicate;
+import java.util.stream.Stream;
 
 import org.apache.commons.lang3.ArrayUtils;
 
@@ -194,4 +196,16 @@ public class ArrayOperations {
     public static <T> T getRandomFromObjectArray(T[] array) {
         return array[new Random().nextInt(array.length)];
     }
+
+    public static Integer[] intersectionSimple(final Integer[] a, final Integer[] b){
+        return Stream.of(a).filter(Arrays.asList(b)::contains).toArray(Integer[]::new);
+    }
+
+    public static Integer[] intersectionSet(final Integer[] a, final Integer[] b){
+        return Stream.of(a).filter(Arrays.asList(b)::contains).distinct().toArray(Integer[]::new);
+    }
+
+    public static Integer[] intersectionMultiSet(final Integer[] a, final Integer[] b){
+        return Stream.of(a).filter(new LinkedList<>(Arrays.asList(b))::remove).toArray(Integer[]::new);
+    }
 }

core-java-arrays/src/test/java/com/baeldung/array/operations/IntersectionUnitTest.java

@@ -0,0 +1,66 @@
+package com.baeldung.array.operations;
+
+import org.junit.jupiter.api.Test;
+
+import static com.baeldung.array.operations.ArrayOperations.intersectionMultiSet;
+import static com.baeldung.array.operations.ArrayOperations.intersectionSet;
+import static com.baeldung.array.operations.ArrayOperations.intersectionSimple;
+import static org.assertj.core.api.Assertions.assertThat;
+
+class IntersectionUnitTest {
+    private static final Integer[] a = { 1, 3, 2 };
+    private static final Integer[] b = { 4, 3, 2, 4, 2, 3, 4, 4, 3 };
+    private static final Integer[] c = { 1, 3, 2, 3, 3, 2 };
+
+    @Test
+    void whenIntersectionSimpleIsUsed_thenCommonEntriesAreInTheResult() {
+        assertThat(intersectionSimple(a, b)).isEqualTo(new Integer[] { 3, 2 });
+        assertThat(intersectionSimple(b, a)).isEqualTo(new Integer[] { 3, 2, 2, 3, 3 });
+    }
+
+    @Test
+    void whenIntersectionSimpleIsUsedWithAnArrayAndItself_thenTheResultIsTheIdentity() {
+        assertThat(intersectionSimple(b, b)).isEqualTo(b);
+        assertThat(intersectionSimple(a, a)).isEqualTo(a);
+    }
+
+    @Test
+    void whenIntersectionSetIsUsed_thenCommonEntriesAreInTheResult() {
+        assertThat(intersectionSet(b, a)).isEqualTo(new Integer[] { 3, 2 });
+    }
+
+    @Test
+    void whenIntersectionSetIsUsed_thenTheNumberOfEntriesDoesNotChangeWithTheParameterOrder() {
+        assertThat(intersectionSet(a, b)).isEqualTo(new Integer[] { 3, 2 });
+        assertThat(intersectionSet(b, a)).isEqualTo(new Integer[] { 3, 2 });
+    }
+
+    @Test
+    void whenIntersectionSetIsUsedWithAnArrayAndWithItself_andTheInputHasNoDuplicateEntries_ThenTheResultIsTheIdentity() {
+        assertThat(intersectionSet(a, a)).isEqualTo(a);
+    }
+
+    @Test
+    void whenIntersectionSetIsUsedWithAnArrayAndWithItself_andTheInputHasDuplicateEntries_ThenTheResultIsNotTheIdentity() {
+        assertThat(intersectionSet(b, b)).isNotEqualTo(b);
+    }
+
+    @Test
+    void whenMultiSetIsUsed_thenCommonEntriesAreInTheResult() {
+        assertThat(intersectionMultiSet(b, a)).isEqualTo(new Integer[] { 3, 2 });
+    }
+
+    @Test
+    void whenIntersectionMultiSetIsUsed_thenTheNumberOfEntriesDoesNotChangeWithTheParameterOrder() {
+        assertThat(intersectionMultiSet(a, b)).isEqualTo(new Integer[] { 3, 2 });
+        assertThat(intersectionMultiSet(b, a)).isEqualTo(new Integer[] { 3, 2 });
+        assertThat(intersectionMultiSet(b, c)).isEqualTo(new Integer[] { 3, 2, 2, 3, 3 });
+        assertThat(intersectionMultiSet(c, b)).isEqualTo(new Integer[] { 3, 2, 3, 3, 2 });
+    }
+
+    @Test
+    void whenIntersectionMultiSetIsUsedWithAnArrayAndWithItself_ThenTheResultIsTheIdentity() {
+        assertThat(intersectionMultiSet(b, b)).isEqualTo(b);
+        assertThat(intersectionMultiSet(a, a)).isEqualTo(a);
+    }
+}

core-java-collections/README.md

@@ -43,3 +43,11 @@
 - [Converting a Collection to ArrayList in Java](https://www.baeldung.com/java-convert-collection-arraylist)
 - [Java 8 Streams: Find Items From One List Based On Values From Another List](https://www.baeldung.com/java-streams-find-list-items)
 - [Combining Different Types of Collections in Java](https://www.baeldung.com/java-combine-collections)
+- [Sorting in Java](http://www.baeldung.com/java-sorting)
+- [A Guide to the Java LinkedList](http://www.baeldung.com/java-linkedlist)
+- [Java List UnsupportedOperationException](http://www.baeldung.com/java-list-unsupported-operation-exception)
+- [Join and Split Arrays and Collections in Java](http://www.baeldung.com/java-join-and-split)
+- [Check If Two Lists are Equal in Java](http://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
+- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
+- [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
+- [A Guide to EnumMap](https://www.baeldung.com/java-enum-map)

core-java-collections/pom.xml

@@ -56,6 +56,12 @@
             <artifactId>commons-exec</artifactId>
             <version>1.3</version>
         </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
     </dependencies>
 
     <properties>
@@ -67,5 +73,6 @@
         <avaitility.version>1.7.0</avaitility.version>
         <assertj.version>3.11.1</assertj.version>
         <eclipse.collections.version>7.1.0</eclipse.collections.version>
+        <lombok.version>1.16.12</lombok.version>
     </properties>
 </project>

core-java-io/README.md

@@ -34,3 +34,4 @@
 - [Read a File into an ArrayList](https://www.baeldung.com/java-file-to-arraylist)
 - [Guide to Java OutputStream](https://www.baeldung.com/java-outputstream)
 - [Reading a CSV File into an Array](https://www.baeldung.com/java-csv-file-array)
+- [Guide to BufferedReader](https://www.baeldung.com/java-buffered-reader)

core-java-lang/README.md

@@ -56,4 +56,5 @@
 - [How to Separate Double into Integer and Decimal Parts](https://www.baeldung.com/java-separate-double-into-integer-decimal-parts)
 - [“Sneaky Throws” in Java](http://www.baeldung.com/java-sneaky-throws)
 - [Inheritance and Composition (Is-a vs Has-a relationship) in Java](http://www.baeldung.com/java-inheritance-composition)
+- [A Guide to Constructors in Java](https://www.baeldung.com/java-constructors)
 

core-java-lang/src/main/java/com/baeldung/constructors/BankAccount.java

@@ -0,0 +1,56 @@
+package com.baeldung.constructors;
+
+import java.time.LocalDateTime;
+
+class BankAccount {
+    String name;
+    LocalDateTime opened;
+    double balance;
+    
+    @Override
+    public String toString() {
+        return String.format("%s, %s, %f", this.name, this.opened.toString(), this.balance);
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public LocalDateTime getOpened() {
+        return opened;
+    }
+
+    public double getBalance() {
+        return this.balance;
+    }
+}
+
+class BankAccountEmptyConstructor extends BankAccount {
+    public BankAccountEmptyConstructor() {
+        this.name = "";
+        this.opened = LocalDateTime.now();
+        this.balance = 0.0d;
+    }
+}
+
+class BankAccountParameterizedConstructor extends BankAccount {
+    public BankAccountParameterizedConstructor(String name, LocalDateTime opened, double balance) {
+        this.name = name;
+        this.opened = opened;
+        this.balance = balance;
+    }
+}
+
+class BankAccountCopyConstructor extends BankAccount {
+    public BankAccountCopyConstructor(String name, LocalDateTime opened, double balance) {
+        this.name = name;
+        this.opened = opened;
+        this.balance = balance;
+    }
+        
+    public BankAccountCopyConstructor(BankAccount other) {
+        this.name = other.name;
+        this.opened = LocalDateTime.now();
+        this.balance = 0.0f;
+    }
+}

core-java-lang/src/main/java/com/baeldung/constructors/Transaction.java

@@ -0,0 +1,25 @@
+package com.baeldung.constructors;
+
+import java.time.LocalDateTime;
+
+class Transaction {
+    final BankAccountEmptyConstructor bankAccount;
+    final LocalDateTime date;
+    final double amount;
+
+    public Transaction(BankAccountEmptyConstructor account, LocalDateTime date, double amount) {
+        this.bankAccount = account;
+        this.date = date;
+        this.amount = amount;
+    }
+
+    /*
+     * Compilation Error :'(, all final variables must be explicitly initialised.
+     * public Transaction() {
+     * }
+     */
+
+    public void invalidMethod() {
+        // this.amount = 102.03; // Results in a compiler error. You cannot change the value of a final variable.
+    }    
+}

core-java-lang/src/test/java/com/baeldung/constructors/ConstructorUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.constructors;
+
+import com.baeldung.constructors.*;
+
+import java.util.logging.Logger;
+import java.time.LocalDateTime;
+import java.time.Month;
+
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class ConstructorUnitTest {
+    final static Logger LOGGER = Logger.getLogger(ConstructorUnitTest.class.getName());
+
+    @Test
+    public void givenNoExplicitContructor_whenUsed_thenFails() {
+        BankAccount account = new BankAccount();
+        assertThatThrownBy(() -> { account.toString(); }).isInstanceOf(Exception.class);
+    }
+
+    @Test
+    public void givenNoArgumentConstructor_whenUsed_thenSucceeds() {
+        BankAccountEmptyConstructor account = new BankAccountEmptyConstructor();
+        assertThatCode(() -> {
+                account.toString();
+            }).doesNotThrowAnyException();
+    }
+
+    @Test
+    public void givenParameterisedConstructor_whenUsed_thenSucceeds() {
+        LocalDateTime opened = LocalDateTime.of(2018, Month.JUNE, 29, 06, 30, 00);
+        BankAccountParameterizedConstructor account =
+            new BankAccountParameterizedConstructor("Tom", opened, 1000.0f);
+        
+        assertThatCode(() -> {
+                account.toString();
+            }).doesNotThrowAnyException();
+    }
+
+    @Test
+    public void givenCopyContructor_whenUser_thenMaintainsLogic() {
+        LocalDateTime opened = LocalDateTime.of(2018, Month.JUNE, 29, 06, 30, 00);
+        BankAccountCopyConstructor account = new BankAccountCopyConstructor("Tim", opened, 1000.0f);
+        BankAccountCopyConstructor newAccount = new BankAccountCopyConstructor(account);
+
+        assertThat(account.getName()).isEqualTo(newAccount.getName());
+        assertThat(account.getOpened()).isNotEqualTo(newAccount.getOpened());
+        
+        assertThat(newAccount.getBalance()).isEqualTo(0.0f);
+    }
+}

core-java/README.md

@@ -10,7 +10,6 @@
 - [Guide to the Fork/Join Framework in Java](http://www.baeldung.com/java-fork-join)
 - [How to Print Screen in Java](http://www.baeldung.com/print-screen-in-java)
 - [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
-- [Sorting in Java](http://www.baeldung.com/java-sorting)
 - [Getting Started with Java Properties](http://www.baeldung.com/java-properties)
 - [Pattern Search with Grep in Java](http://www.baeldung.com/grep-in-java)
 - [URL Encoding and Decoding in Java](http://www.baeldung.com/java-url-encoding-decoding)
@@ -39,7 +38,6 @@
 - [Quick Guide to Java Stack](http://www.baeldung.com/java-stack)
 - [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
 - [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
-- [Implementing a Binary Tree in Java](http://www.baeldung.com/java-binary-tree)
 - [A Guide to ThreadLocalRandom in Java](http://www.baeldung.com/java-thread-local-random)
 - [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)
 - [A Guide to Iterator in Java](http://www.baeldung.com/java-iterator)
@@ -49,15 +47,10 @@
 - [A Practical Guide to DecimalFormat](http://www.baeldung.com/java-decimalformat)
 - [How to Detect the OS Using Java](http://www.baeldung.com/java-detect-os)
 - [ASCII Art in Java](http://www.baeldung.com/ascii-art-in-java)
-- [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max)
 - [What is the serialVersionUID?](http://www.baeldung.com/java-serial-version-uid)
 - [A Guide To UDP In Java](http://www.baeldung.com/udp-in-java)
-- [A Guide to the Java LinkedList](http://www.baeldung.com/java-linkedlist)
 - [A Guide to the ResourceBundle](http://www.baeldung.com/java-resourcebundle)
 - [Class Loaders in Java](http://www.baeldung.com/java-classloaders)
-- [Java List UnsupportedOperationException](http://www.baeldung.com/java-list-unsupported-operation-exception)
-- [Join and Split Arrays and Collections in Java](http://www.baeldung.com/java-join-and-split)
-- [Check If Two Lists are Equal in Java](http://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
 - [Sending Emails with Java](http://www.baeldung.com/java-email)
 - [Introduction to SSL in Java](http://www.baeldung.com/java-ssl)
 - [Java KeyStore API](http://www.baeldung.com/java-keystore)
@@ -80,8 +73,6 @@
 - [Getting a File’s Mime Type in Java](http://www.baeldung.com/java-file-mime-type)
 - [Common Java Exceptions](http://www.baeldung.com/java-common-exceptions)
 - [Java Constructors vs Static Factory Methods](https://www.baeldung.com/java-constructors-vs-static-factory-methods)
-- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
-- [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
 - [Throw Exception in Optional in Java 8](https://www.baeldung.com/java-optional-throw-exception)
 - [Add a Character to a String at a Given Position](https://www.baeldung.com/java-add-character-to-string)
 - [Calculating the nth Root in Java](https://www.baeldung.com/java-nth-root)
@@ -93,3 +84,7 @@
 - [Understanding Memory Leaks in Java](https://www.baeldung.com/java-memory-leaks)
 - [A Guide to SimpleDateFormat](https://www.baeldung.com/java-simple-date-format)
 - [SSL Handshake Failures](https://www.baeldung.com/java-ssl-handshake-failures)
+- [Implementing a Binary Tree in Java](https://www.baeldung.com/java-binary-tree)
+- [Changing the Order in a Sum Operation Can Produce Different Results?](https://www.baeldung.com/java-floating-point-sum-order)
+- [Java – Try with Resources](https://www.baeldung.com/java-try-with-resources)
+- [Abstract Classes in Java](https://www.baeldung.com/java-abstract-class)

core-java/src/main/java/com/baeldung/abstractclasses/application/Application.java

@@ -2,29 +2,28 @@ package com.baeldung.abstractclasses.application;
 
 import com.baeldung.abstractclasses.filereaders.BaseFileReader;
 import com.baeldung.abstractclasses.filereaders.LowercaseFileReader;
-import com.baeldung.abstractclasses.filereaders.StandardFileReader;
 import com.baeldung.abstractclasses.filereaders.UppercaseFileReader;
 import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 
 public class Application {
 
-    public static void main(String[] args) throws IOException {
-        
+    public static void main(String[] args) throws IOException, URISyntaxException {
+
         Application application = new Application();
-        String filePath = application.getFilePathFromResourcesFolder("files/test.txt");
-            
-        BaseFileReader lowercaseFileReader = new LowercaseFileReader(filePath);
+        Path path = application.getPathFromResourcesFile("files/test.txt");
+        BaseFileReader lowercaseFileReader = new LowercaseFileReader(path);
         lowercaseFileReader.readFile().forEach(line -> System.out.println(line));
+        
+        BaseFileReader uppercaseFileReader = new UppercaseFileReader(path);
+        uppercaseFileReader.readFile().forEach(line -> System.out.println(line));
 
-        BaseFileReader upperCaseFileReader = new UppercaseFileReader(filePath);
-        upperCaseFileReader.readFile().forEach(line -> System.out.println(line));
-
-        BaseFileReader standardFileReader = new StandardFileReader(filePath);
-        standardFileReader.readFile().forEach(line -> System.out.println(line));
-         
     }
     
-    private String getFilePathFromResourcesFolder(String fileName) {
-        return getClass().getClassLoader().getResource(fileName).getPath().substring(1);
+    private Path getPathFromResourcesFile(String filePath) throws URISyntaxException {
+        return Paths.get(getClass().getClassLoader().getResource(filePath).toURI());
+         
     }
 }

core-java/src/main/java/com/baeldung/abstractclasses/filereaders/BaseFileReader.java

@@ -1,19 +1,27 @@
 package com.baeldung.abstractclasses.filereaders;
 
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public abstract class BaseFileReader {
     
-    protected String filePath;
+    protected Path filePath;
     
-    protected BaseFileReader(String filePath) {
+    protected BaseFileReader(Path filePath) {
         this.filePath = filePath;
     }
     
-    public String getFilePath() {
+    public Path getFilePath() {
         return filePath;
     }
     
-    public abstract List<String> readFile() throws IOException;
+    public List<String> readFile() throws IOException {
+        return Files.lines(filePath)
+            .map(this::mapFileLine).collect(Collectors.toList());
+    }
+    
+    protected abstract String mapFileLine(String line);
 }

core-java/src/main/java/com/baeldung/abstractclasses/filereaders/LowercaseFileReader.java

@@ -1,21 +1,15 @@
 package com.baeldung.abstractclasses.filereaders;
 
-import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import java.util.List;
-import java.util.stream.Collectors;
+import java.nio.file.Path;
 
 public class LowercaseFileReader extends BaseFileReader {
 
-    public LowercaseFileReader(String filePath) {
+    public LowercaseFileReader(Path filePath) {
         super(filePath);
     }
-    
+
     @Override
-    public List<String> readFile() throws IOException {
-        return Files.lines(Paths.get(filePath))
-            .map(String::toLowerCase)
-            .collect(Collectors.toList());
-    }
+    public String mapFileLine(String line) {
+        return line.toLowerCase();
+    }   
 }

core-java/src/main/java/com/baeldung/abstractclasses/filereaders/StandardFileReader.java

@@ -1,19 +0,0 @@
-package com.baeldung.abstractclasses.filereaders;
-
-import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import java.util.List;
-import java.util.stream.Collectors;
-
-public class StandardFileReader extends BaseFileReader {
-
-    public StandardFileReader(String filePath) {
-        super(filePath);
-    }
-    
-    @Override
-    public List<String> readFile() throws IOException {
-        return Files.lines(Paths.get(filePath)).collect(Collectors.toList());
-    }
-}

core-java/src/main/java/com/baeldung/abstractclasses/filereaders/UppercaseFileReader.java

@@ -1,21 +1,15 @@
 package com.baeldung.abstractclasses.filereaders;
 
-import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import java.util.List;
-import java.util.stream.Collectors;
+import java.nio.file.Path;
 
 public class UppercaseFileReader extends BaseFileReader {
-    
-    public UppercaseFileReader(String filePath) {
+
+    public UppercaseFileReader(Path filePath) {
         super(filePath);
     }
-    
+
     @Override
-    public List<String> readFile() throws IOException {
-        return Files.lines(Paths.get(filePath))
-            .map(String::toUpperCase)
-            .collect(Collectors.toList());
+    public String mapFileLine(String line) {
+        return line.toUpperCase();
     }
 }

core-java/src/main/java/com/baeldung/className/RetrievingClassName.java

@@ -0,0 +1,9 @@
+package com.baeldung.className;
+
+public class RetrievingClassName {
+
+    public class InnerClass {
+
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/CommandLineProxyDemo.java

@@ -0,0 +1,17 @@
+package com.baeldung.networking.proxies;
+
+import java.net.URL;
+import java.net.URLConnection;
+
+public class CommandLineProxyDemo {
+
+    public static final String RESOURCE_URL = "http://www.google.com";
+
+    public static void main(String[] args) throws Exception {
+
+        URL url = new URL(RESOURCE_URL);
+        URLConnection con = url.openConnection();
+        System.out.println(UrlConnectionUtils.contentAsString(con));
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/DirectProxyDemo.java

@@ -0,0 +1,20 @@
+package com.baeldung.networking.proxies;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.Proxy;
+import java.net.URL;
+
+public class DirectProxyDemo {
+
+    private static final String URL_STRING = "http://www.google.com";
+
+    public static void main(String... args) throws IOException {
+
+        URL weburl = new URL(URL_STRING);
+        HttpURLConnection directConnection 
+          = (HttpURLConnection) weburl.openConnection(Proxy.NO_PROXY);
+        System.out.println(UrlConnectionUtils.contentAsString(directConnection));
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/SocksProxyDemo.java

@@ -0,0 +1,32 @@
+package com.baeldung.networking.proxies;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.Socket;
+import java.net.URL;
+
+public class SocksProxyDemo {
+
+    private static final String URL_STRING = "http://www.google.com";
+    private static final String SOCKET_SERVER_HOST = "someserver.baeldung.com";
+    private static final int SOCKET_SERVER_PORT = 1111;
+
+    public static void main(String... args) throws IOException {
+
+        URL weburl = new URL(URL_STRING);
+        Proxy socksProxy 
+          = new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("127.0.0.1", 1080));
+        HttpURLConnection socksConnection 
+          = (HttpURLConnection) weburl.openConnection(socksProxy);
+        System.out.println(UrlConnectionUtils.contentAsString(socksConnection));
+
+        Socket proxySocket = new Socket(socksProxy);
+        InetSocketAddress socketHost 
+          = new InetSocketAddress(SOCKET_SERVER_HOST, SOCKET_SERVER_PORT);
+        proxySocket.connect(socketHost);
+        // do stuff with the socket
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/SystemPropertyProxyDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.networking.proxies;
+
+import java.net.URL;
+import java.net.URLConnection;
+
+public class SystemPropertyProxyDemo {
+
+    public static final String RESOURCE_URL = "http://www.google.com";
+
+    public static void main(String[] args) throws Exception {
+
+        System.setProperty("http.proxyHost", "127.0.0.1");
+        System.setProperty("http.proxyPort", "3128");
+
+        URL url = new URL(RESOURCE_URL);
+        URLConnection con = url.openConnection();
+        System.out.println(UrlConnectionUtils.contentAsString(con));
+
+        System.setProperty("http.proxyHost", null);
+        // proxy will no longer be used for http connections
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/UrlConnectionUtils.java

@@ -0,0 +1,21 @@
+package com.baeldung.networking.proxies;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URLConnection;
+
+class UrlConnectionUtils {
+
+    public static String contentAsString(URLConnection con) throws IOException {
+        StringBuilder builder = new StringBuilder();
+        try (BufferedReader reader 
+                = new BufferedReader(new InputStreamReader(con.getInputStream()))){
+            while (reader.ready()) {
+                builder.append(reader.readLine());
+            }
+        }
+        return builder.toString();
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/WebProxyDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.networking.proxies;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.URL;
+
+public class WebProxyDemo {
+
+    private static final String URL_STRING = "http://www.google.com";
+
+    public static void main(String... args) throws IOException {
+
+        URL weburl = new URL(URL_STRING);
+        Proxy webProxy 
+          = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("127.0.0.1", 3128));
+        HttpURLConnection webProxyConnection 
+            = (HttpURLConnection) weburl.openConnection(webProxy);
+        System.out.println(UrlConnectionUtils.contentAsString(webProxyConnection));
+    }
+
+}