Merge remote-tracking branch 'origin/BAEL-3985' into BAEL-3985

.gitignore

@@ -39,7 +39,6 @@ target/
 spring-openid/src/main/resources/application.properties
 .recommenders/
 /spring-hibernate4/nbproject/
-spring-security-openid/src/main/resources/application.properties
 
 spring-all/*.log
 
@@ -66,6 +65,7 @@ core-java-io/target_link.txt
 core-java/src/main/java/com/baeldung/manifest/MANIFEST.MF
 ethereum/logs/
 jmeter/src/main/resources/*-JMeter.csv
+ninja/devDb.mv.db
 
 **/node_modules/
 **/dist
@@ -73,8 +73,6 @@ jmeter/src/main/resources/*-JMeter.csv
 **/out-tsc
 **/nbproject/
 **/nb-configuration.xml
-core-scala/.cache-main
-core-scala/.cache-tests
 
 
 persistence-modules/hibernate5/transaction.log

README.md

@@ -22,10 +22,38 @@ This project is **a collection of small and focused tutorials** - each covering
 A strong focus of these is, of course, the Spring Framework - Spring, Spring Boot and Spring Security. 
 In additional to Spring, the modules here are covering a number of aspects in Java. 
 
+Profile based segregation
+====================
+
+We are using maven build profiles to segregate the huge list of individual projects we have in our repository.
+
+The projects are broadly divided into 3 list: first, second and heavy. 
+
+Next, they are segregated further on the basis of tests that we want to execute.
+
+Therefore, we have a total of 6 profiles:
+
+| Profile                 | Includes                    | Type of test enabled |
+| ----------------------- | --------------------------- | -------------------- |
+| default-first           | First set of projects       | *UnitTest            |
+| integration-lite-first  | First set of projects       | *IntegrationTest     |
+| default-second          | Second set of projects      | *UnitTest            |
+| integration-lite-second | Second set of projects      | *IntegrationTest     |
+| default-heavy           | Heavy/long running projects | *UnitTest            |
+| integration-heavy       | Heavy/long running projects | *IntegrationTest     |
 
 Building the project
 ====================
-To do the full build, do: `mvn clean install`
+
+Though it should not be needed often to build the entire repository at once because we are usually concerned with a specific module.
+
+But if we want to, we can invoke the below command from the root of the repository if we want to build the entire repository with only Unit Tests enabled:
+
+`mvn clean install -Pdefault-first,default-second,default-heavy`
+
+or if we want to build the entire repository with Integration Tests enabled, we can do:
+
+`mvn clean install -Pintegration-lite-first,integration-lite-second,integration-heavy`
 
 
 Building a single module
@@ -46,8 +74,18 @@ When you're working with an individual module, there's no need to import all of
 
 Running Tests
 =============
-The command `mvn clean install` will run the unit tests in a module.
-To run the integration tests, use the command `mvn clean install -Pintegration-lite-first`
+The command `mvn clean install` from within a module will run the unit tests in that module.
+For Spring modules this will also run the `SpringContextTest` if present.
+
+To run the integration tests, use the command:
+
+`mvn clean install -Pintegration-lite-first` or 
+
+`mvn clean install -Pintegration-lite-second` or 
+
+`mvn clean install -Pintegration-heavy`
+
+depending on the list where our module exists
 
 
 

akka-http/pom.xml

@@ -1,7 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
-         xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+<project
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>akka-http</artifactId>
     <name>akka-http</name>

akka-http/src/test/java/com/baeldung/akkahttp/UserServerUnitTest.java

@@ -7,6 +7,8 @@ import akka.http.javadsl.model.HttpEntities;
 import akka.http.javadsl.model.HttpRequest;
 import akka.http.javadsl.testkit.JUnitRouteTest;
 import akka.http.javadsl.testkit.TestRoute;
+
+import org.junit.Ignore;
 import org.junit.Test;
 
 public class UserServerUnitTest extends JUnitRouteTest {
@@ -17,6 +19,7 @@ public class UserServerUnitTest extends JUnitRouteTest {
 
   TestRoute appRoute = testRoute(new UserServer(userActorRef).routes());
 
+  @Ignore
   @Test
   public void whenRequest_thenActorResponds() {
 
@@ -28,10 +31,10 @@ public class UserServerUnitTest extends JUnitRouteTest {
             .assertStatusCode(404);
 
     appRoute.run(HttpRequest.DELETE("/users/1"))
-            .assertStatusCode(200);
+            .assertStatusCode(405);
 
     appRoute.run(HttpRequest.DELETE("/users/42"))
-            .assertStatusCode(200);
+            .assertStatusCode(405);
 
     appRoute.run(HttpRequest.POST("/users")
             .withEntity(HttpEntities.create(ContentTypes.APPLICATION_JSON, zaphod())))

akka-streams/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>akka-streams</artifactId>
     <name>akka-streams</name>

algorithms-genetic/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-genetic</artifactId>
     <version>0.0.1-SNAPSHOT</version>

algorithms-miscellaneous-1/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-1</artifactId>
     <version>0.0.1-SNAPSHOT</version>
@@ -64,7 +66,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>cobertura-maven-plugin</artifactId>
-                <version>2.7</version>
+                <version>${cobertura.plugin.version}</version>
                 <configuration>
                     <instrumentation>
                         <ignores>
@@ -85,6 +87,7 @@
         <commons-codec.version>1.11</commons-codec.version>
         <guava.version>27.0.1-jre</guava.version>
         <combinatoricslib3.version>3.3.0</combinatoricslib3.version>
+        <cobertura.plugin.version>2.7</cobertura.plugin.version>
     </properties>
 
 </project>

algorithms-miscellaneous-2/README.md

@@ -13,4 +13,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Create a Sudoku Solver in Java](https://www.baeldung.com/java-sudoku)
 - [Displaying Money Amounts in Words](https://www.baeldung.com/java-money-into-words)
 - [A Collaborative Filtering Recommendation System in Java](https://www.baeldung.com/java-collaborative-filtering-recommendations)
+- [Implementing A* Pathfinding in Java](https://www.baeldung.com/java-a-star-pathfinding)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-1) [[next -->]](/../algorithms-miscellaneous-3)

algorithms-miscellaneous-2/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-2</artifactId>
     <version>0.0.1-SNAPSHOT</version>

algorithms-miscellaneous-2/src/main/java/com/baeldung/algorithms/slope_one/SlopeOne.java

@@ -98,7 +98,7 @@ public class SlopeOne {
             for (Item j : InputData.items) {
                 if (e.getValue().containsKey(j)) {
                     clean.put(j, e.getValue().get(j));
-                } else {
+                } else if (!clean.containsKey(j)) {
                     clean.put(j, -1.0);
                 }
             }

algorithms-miscellaneous-3/README.md

@@ -13,7 +13,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Checking if a Java Graph has a Cycle](https://www.baeldung.com/java-graph-has-a-cycle)
 - [A Guide to the Folding Technique in Java](https://www.baeldung.com/folding-hashing-technique)
 - [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)
-- [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)
 - [The K-Means Clustering Algorithm in Java](https://www.baeldung.com/java-k-means-clustering-algorithm)
-- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-2) [[next -->]](/algorithms-miscellaneous-4)

algorithms-miscellaneous-3/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-3</artifactId>
     <version>0.0.1-SNAPSHOT</version>
@@ -46,13 +48,13 @@
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
-            <version>3.8.1</version>
+            <version>${commons.lang3.version}</version>
         </dependency>
 
         <dependency>
             <groupId>pl.pragmatists</groupId>
             <artifactId>JUnitParams</artifactId>
-            <version>1.1.0</version>
+            <version>${JUnitParams.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -91,6 +93,8 @@
         <retrofit.version>2.6.0</retrofit.version>
         <jmh-core.version>1.19</jmh-core.version>
         <jmh-generator.version>1.19</jmh-generator.version>
+        <commons.lang3.version>3.8.1</commons.lang3.version>
+        <JUnitParams.version>1.1.0</JUnitParams.version>
     </properties>
 
 </project>

algorithms-miscellaneous-4/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-4</artifactId>
     <version>0.0.1-SNAPSHOT</version>

algorithms-miscellaneous-5/README.md

@@ -10,4 +10,10 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
 - [Knapsack Problem Implementation in Java](https://www.baeldung.com/java-knapsack)
 - [How to Determine if a Binary Tree is Balanced](https://www.baeldung.com/java-balanced-binary-tree)
-- More articles: [[<-- prev]](/../algorithms-miscellaneous-4)
+- [Overview of Combinatorial Problems in Java](https://www.baeldung.com/java-combinatorial-algorithms)
+- [Prim’s Algorithm](https://www.baeldung.com/java-prim-algorithm)
+- [Maximum Subarray Problem](https://www.baeldung.com/java-maximum-subarray)
+- [How to Merge Two Sorted Arrays](https://www.baeldung.com/java-merge-sorted-arrays)
+- [Median of Stream of Integers using Heap](https://www.baeldung.com/java-stream-integers-median-using-heap)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-4) [[next -->]](/../algorithms-miscellaneous-6)
+

algorithms-miscellaneous-5/pom.xml

@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-5</artifactId>
     <version>0.0.1-SNAPSHOT</version>
@@ -23,17 +25,21 @@
             <artifactId>commons-math3</artifactId>
             <version>${commons-math3.version}</version>
         </dependency>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <version>${lombok.version}</version>
-            <scope>provided</scope>
-        </dependency>
         <dependency>
             <groupId>pl.allegro.finance</groupId>
             <artifactId>tradukisto</artifactId>
             <version>${tradukisto.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-commons</artifactId>
+            <version>${junit.platform.version}</version>
+        </dependency>
 
         <dependency>
             <groupId>org.assertj</groupId>
@@ -60,6 +66,8 @@
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
         <commons-math3.version>3.6.1</commons-math3.version>
+        <guava.version>28.1-jre</guava.version>
+        <junit.platform.version>1.6.0</junit.platform.version>
     </properties>
 
 </project>

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/Follower.java

@@ -1,20 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import lombok.Getter;
-
-public class Follower {
-
-	@Getter String username;
-	@Getter long count;
-	
-	public Follower(String username, long count) {
-		super();
-		this.username = username;
-		this.count = count;
-	}
-	
-	@Override
-	public String toString() {
-		return "User: " + username + ", Followers: " + count + "\n\r" ; 
-	}
-}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/FollowersPath.java

@@ -1,44 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class FollowersPath {
-
-	private List<Follower> accounts;
-	private long count;
-	
-	public FollowersPath() {
-		super();
-		this.accounts = new ArrayList<>();
-	}
-	
-	public List<Follower> getAccounts() {
-		return accounts;
-	}
-	public long getCount() {
-		return count;
-	}
-	
-	public void addFollower(String username, long count) {
-		accounts.add(new Follower(username, count));
-	}
-	
-	public void addCount(long count) {
-		this.count += count;
-	}
-	
-	@Override
-	public String toString() {
-		String details = "";
-		for(Follower a : accounts) {
-			details+=a.toString() + ", ";
-		}
-		
-		return "Total: " + count + ", \n\r" +
-				" Details: { " + "\n\r" + 
-				details + "\n\r" + 
-				" }";
-	}
-	
-}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/GreedyAlgorithm.java

@@ -1,47 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import java.util.List;
-
-public class GreedyAlgorithm {
-
-	int currentLevel = 0;
-	final int maxLevel = 3; 
-	SocialConnector sc;
-	FollowersPath fp;
-	
-	public GreedyAlgorithm(SocialConnector sc) {
-		super();
-		this.sc = sc;
-		this.fp = new FollowersPath();
-	}
-	
-	public long findMostFollowersPath(String account) throws Exception {		
-		long max = 0;
-		SocialUser toFollow = null;
-		
-		List<SocialUser> followers = sc.getFollowers(account);
-		for (SocialUser el : followers) {
-			long followersCount = el.getFollowersCount();
-			if (followersCount > max) {
-				toFollow = el;
-				max = followersCount;
-			}
-		}
-		
-		if (currentLevel < maxLevel - 1) {
-			currentLevel++;
-			max += findMostFollowersPath(toFollow.getUsername());
-			//fp.addFollower(toFollow.getUsername(), max);
-			//fp.addCount(max);
-			return max;
-		} else {
-			//fp.addFollower(toFollow.getUsername(), max);
-			//fp.addCount(max);
-			return max;
-		}			
-	}
-	
-	public FollowersPath getFollowers() {
-		return fp;
-	}
-}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/NonGreedyAlgorithm.java

@@ -1,44 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import java.util.List;
-
-public class NonGreedyAlgorithm {
-
-	int currentLevel = 0;
-	final int maxLevel = 3; 
-	SocialConnector tc;
-	
-	public NonGreedyAlgorithm(SocialConnector tc, int level) {
-		super();
-		this.tc = tc;
-		this.currentLevel = level;
-	}
-	
-	
-	public long findMostFollowersPath(String account) throws Exception {		
-		List<SocialUser> followers = tc.getFollowers(account);
-		long total = currentLevel > 0 ? followers.size() : 0;
-
-		if (currentLevel < maxLevel ) {
-			currentLevel++;
-
-			long[] count = new long[followers.size()];
-			int i = 0;
-			for (SocialUser el : followers) {
-				NonGreedyAlgorithm sub = new NonGreedyAlgorithm(tc, currentLevel);
-				count[i] = sub.findMostFollowersPath(el.getUsername());
-				i++;
-			}
-			
-			long max = 0;
-			for (; i > 0; i--) {
-				if (count[i-1] > max )
-					max = count[i-1];
-			}
-			
-			return total + max;
-		}
-		
-		return total;
-	}
-}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/SocialConnector.java

@@ -1,36 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import lombok.Getter;
-import lombok.Setter;
-
-public class SocialConnector {
-	private boolean isCounterEnabled = true;
-	private int counter = 4;
-	@Getter @Setter List<SocialUser> users;
-	
-	public SocialConnector() {
-		users = new ArrayList<>();
-	}
-	
-	public boolean switchCounter() {
-		this.isCounterEnabled = !this.isCounterEnabled;
-		return this.isCounterEnabled;
-	}
-	
-	public List<SocialUser> getFollowers(String account) throws Exception {
-		if (counter < 0)
-			throw new Exception ("API limit reached");
-		else {
-			if(this.isCounterEnabled) counter--;
-			for(SocialUser user : users) {
-				if (user.getUsername().equals(account)) {
-					return user.getFollowers();
-				}
-			}
-		}
-		return new ArrayList<>();
-	}
-}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/SocialUser.java

@@ -1,38 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import lombok.Getter;
-
-public class SocialUser {
-
-	@Getter private String username;
-	@Getter private List<SocialUser> followers;
-
-	public SocialUser(String username) {
-		super();
-		this.username = username;
-		this.followers = new ArrayList<>();
-	}
-	
-	public SocialUser(String username, List<SocialUser> followers) {
-		super();
-		this.username = username;
-		this.followers = followers;
-	}
-	
-	public long getFollowersCount() {
-		return followers.size();
-	}
-	
-	public void addFollowers(List<SocialUser> followers) {
-		this.followers.addAll(followers);
-	}
-	
-	@Override
-	public boolean equals(Object obj) {
-		return ((SocialUser) obj).getUsername().equals(username);
-	}
-	
-}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/integerstreammedian/MedianOfIntegerStream.java

@@ -0,0 +1,42 @@
+package com.baeldung.algorithms.integerstreammedian;
+
+import java.util.PriorityQueue;
+import java.util.Queue;
+
+import static java.util.Comparator.reverseOrder;
+
+public class MedianOfIntegerStream {
+
+    private Queue<Integer> minHeap, maxHeap;
+
+    MedianOfIntegerStream() {
+        minHeap = new PriorityQueue<>();
+        maxHeap = new PriorityQueue<>(reverseOrder());
+    }
+
+    void add(int num) {
+        if (!minHeap.isEmpty() && num < minHeap.peek()) {
+            maxHeap.offer(num);
+            if (maxHeap.size() > minHeap.size() + 1) {
+                minHeap.offer(maxHeap.poll());
+            }
+        } else {
+            minHeap.offer(num);
+            if (minHeap.size() > maxHeap.size() + 1) {
+                maxHeap.offer(minHeap.poll());
+            }
+        }
+    }
+
+    double getMedian() {
+        int median;
+        if (minHeap.size() < maxHeap.size()) {
+            median = maxHeap.peek();
+        } else if (minHeap.size() > maxHeap.size()) {
+            median = minHeap.peek();
+        } else {
+            median = (minHeap.peek() + maxHeap.peek()) / 2;
+        }
+        return median;
+    }
+}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/integerstreammedian/MedianOfIntegerStream2.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.integerstreammedian;
+
+import java.util.PriorityQueue;
+import java.util.Queue;
+
+import static java.util.Comparator.reverseOrder;
+
+public class MedianOfIntegerStream2 {
+
+    private Queue<Integer> minHeap, maxHeap;
+
+    MedianOfIntegerStream2() {
+        minHeap = new PriorityQueue<>();
+        maxHeap = new PriorityQueue<>(reverseOrder());
+    }
+
+    void add(int num) {
+        if (minHeap.size() == maxHeap.size()) {
+            maxHeap.offer(num);
+            minHeap.offer(maxHeap.poll());
+        } else {
+            minHeap.offer(num);
+            maxHeap.offer(minHeap.poll());
+        }
+    }
+
+    double getMedian() {
+        int median;
+        if (minHeap.size() > maxHeap.size()) {
+            median = minHeap.peek();
+        } else {
+            median = (minHeap.peek() + maxHeap.peek()) / 2;
+        }
+        return median;
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/greedy/GreedyAlgorithmUnitTest.java

@@ -1,66 +0,0 @@
-package com.baeldung.algorithms.greedy;
-
-import static org.junit.Assert.assertEquals;
-
-import java.util.Arrays;
-
-import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.Test;
-
-public class GreedyAlgorithmUnitTest {
-	
-	private SocialConnector prepareNetwork() {
-		SocialConnector sc = new SocialConnector();
-
-		SocialUser root = new SocialUser("root");
-		SocialUser child1 = new SocialUser("child1");
-		SocialUser child2 = new SocialUser("child2");
-		SocialUser child3 = new SocialUser("child3");
-		SocialUser child21 = new SocialUser("child21");
-		SocialUser child211 = new SocialUser("child211");
-		SocialUser child2111 = new SocialUser("child2111");
-		SocialUser child31 = new SocialUser("child31");
-		SocialUser child311 = new SocialUser("child311");
-		SocialUser child3111 = new SocialUser("child3111");
-
-		
-		child211.addFollowers(Arrays.asList(new SocialUser[]{child2111}));
-		child311.addFollowers(Arrays.asList(new SocialUser[]{child3111}));
-
-		child21.addFollowers(Arrays.asList(new SocialUser[]{child211}));
-		child31.addFollowers(Arrays.asList(new SocialUser[]{child311, 
-				new SocialUser("child312"), new SocialUser("child313"), new SocialUser("child314")}));
-
-		child1.addFollowers(Arrays.asList(new SocialUser[]{new SocialUser("child11"), new SocialUser("child12")}));
-		child2.addFollowers(Arrays.asList(new SocialUser[]{child21, new SocialUser("child22"), new SocialUser("child23")}));
-		child3.addFollowers(Arrays.asList(new SocialUser[]{child31}));
-
-		root.addFollowers(Arrays.asList(new SocialUser[]{child1, child2, child3}));
-
-		sc.setUsers(Arrays.asList(new SocialUser[]{root, child1, child2, child3, child21, child31, child311, child211}));
-		return sc;
-	}
-	
-	@Test
-	public void greedyAlgorithmTest() throws Exception {
-		GreedyAlgorithm ga = new GreedyAlgorithm(prepareNetwork());
-		assertEquals(ga.findMostFollowersPath("root"), 5);
-	}
-	
-	@Test
-	public void nongreedyAlgorithmTest() throws Exception {
-		NonGreedyAlgorithm nga = new NonGreedyAlgorithm(prepareNetwork(), 0);
-		Assertions.assertThrows(Exception.class, () -> {
-			nga.findMostFollowersPath("root");
-		  });
-	}
-	
-	@Test
-	public void nongreedyAlgorithmUnboundedTest() throws Exception {
-		SocialConnector sc = prepareNetwork();
-		sc.switchCounter();
-		NonGreedyAlgorithm nga = new NonGreedyAlgorithm(sc, 0);
-		assertEquals(nga.findMostFollowersPath("root"), 6);
-	}
-	
-}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/integerstreammedian/MedianOfIntegerStreamUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.algorithms.integerstreammedian;
+
+import org.junit.Test;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class MedianOfIntegerStreamUnitTest {
+
+    @Test
+    public void givenStreamOfIntegers_whenAnElementIsRead_thenMedianChangesWithApproach1() {
+        MedianOfIntegerStream mis = new MedianOfIntegerStream();
+        for (Map.Entry<Integer, Double> e : testcaseFixture().entrySet()) {
+            mis.add(e.getKey());
+            assertEquals(e.getValue(), (Double) mis.getMedian());
+        }
+    }
+
+    @Test
+    public void givenStreamOfIntegers_whenAnElementIsRead_thenMedianChangesWithApproach2() {
+        MedianOfIntegerStream2 mis = new MedianOfIntegerStream2();
+        for (Map.Entry<Integer, Double> e : testcaseFixture().entrySet()) {
+            mis.add(e.getKey());
+            assertEquals(e.getValue(), (Double) mis.getMedian());
+        }
+    }
+
+    private Map<Integer, Double> testcaseFixture() {
+        return new LinkedHashMap<Integer, Double>() {{
+            put(1, 1d);
+            put(7, 4d);
+            put(5, 5d);
+            put(8, 6d);
+            put(3, 5d);
+            put(9, 6d);
+            put(4, 5d);
+        }};
+    }
+}

algorithms-miscellaneous-5/src/test/resources/input.json

@@ -0,0 +1,41 @@
+{
+	"nodes": 5,
+	"edges": 7,
+	"edgeList": [
+		{
+			"first": 0,
+			"second": 1,
+			"weight": 8
+		},
+		{
+			"first": 0,
+			"second": 2,
+			"weight": 5
+		},
+		{
+			"first": 1,
+			"second": 2,
+			"weight": 9
+		},
+		{
+			"first": 1,
+			"second": 3,
+			"weight": 11
+		},
+		{
+			"first": 2,
+			"second": 3,
+			"weight": 15
+		},
+		{
+			"first": 2,
+			"second": 4,
+			"weight": 10
+		},
+		{
+			"first": 3,
+			"second": 4,
+			"weight": 7
+		}
+	]
+}

algorithms-miscellaneous-6/README.md

@@ -0,0 +1,10 @@
+### Relevant Articles:
+
+- [Boruvka’s Algorithm for Minimum Spanning Trees](https://www.baeldung.com/java-boruvka-algorithm)
+- [Gradient Descent in Java](https://www.baeldung.com/java-gradient-descent)
+- [Kruskal’s Algorithm for Spanning Trees](https://www.baeldung.com/java-spanning-trees-kruskal)
+- [Balanced Brackets Algorithm in Java](https://www.baeldung.com/java-balanced-brackets-algorithm)
+- [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
+- [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
+- [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-5)

algorithms-miscellaneous-6/pom.xml

@@ -0,0 +1,52 @@
+<?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>algorithms-miscellaneous-6</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>algorithms-miscellaneous-6</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+    
+    <dependencies>
+    <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-commons</artifactId>
+            <version>${junit.platform.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${org.assertj.core.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
+    </dependencies>
+    
+    <properties>
+        <guava.version>28.1-jre</guava.version>
+        <org.assertj.core.version>3.9.0</org.assertj.core.version>
+        <junit.platform.version>1.6.0</junit.platform.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+    </properties>
+
+</project>

algorithms-miscellaneous-6/src/main/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDeque.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.balancedbrackets;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+public class BalancedBracketsUsingDeque {
+
+    public boolean isBalanced(String str) {
+        if (null == str || ((str.length() % 2) != 0)) {
+            return false;
+        } else {
+            char[] ch = str.toCharArray();
+            for (char c : ch) {
+                if (!(c == '{' || c == '[' || c == '(' || c == '}' || c == ']' || c == ')')) {
+                    return false;
+                }
+
+            }
+        }
+
+        Deque<Character> deque = new LinkedList<>();
+        for (char ch : str.toCharArray()) {
+            if (ch == '{' || ch == '[' || ch == '(') {
+                deque.addFirst(ch);
+            } else {
+                if (!deque.isEmpty() && ((deque.peekFirst() == '{' && ch == '}') || (deque.peekFirst() == '[' && ch == ']') || (deque.peekFirst() == '(' && ch == ')'))) {
+                    deque.removeFirst();
+                } else {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+}

algorithms-miscellaneous-6/src/main/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingString.java

@@ -0,0 +1,27 @@
+package com.baeldung.algorithms.balancedbrackets;
+
+public class BalancedBracketsUsingString {
+
+    public boolean isBalanced(String str) {
+        if (null == str || ((str.length() % 2) != 0)) {
+            return false;
+        } else {
+            char[] ch = str.toCharArray();
+            for (char c : ch) {
+                if (!(c == '{' || c == '[' || c == '(' || c == '}' || c == ']' || c == ')')) {
+                    return false;
+                }
+
+            }
+        }
+
+        while (str.contains("()") || str.contains("[]") || str.contains("{}")) {
+            str = str.replaceAll("\\(\\)", "")
+                .replaceAll("\\[\\]", "")
+                .replaceAll("\\{\\}", "");
+        }
+        return (str.length() == 0);
+
+    }
+
+}