sync with origin

JGit/pom.xml

@@ -1,5 +1,6 @@
 <?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>
     <groupId>com.baeldung</groupId>
     <artifactId>JGitSnippets</artifactId>
@@ -45,7 +46,6 @@
     </dependencies>
 
     <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <org.eclipse.jgit.version>4.5.0.201609210915-r</org.eclipse.jgit.version>
     </properties>
 

Twitter4J/pom.xml

@@ -1,6 +1,7 @@
 <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/maven-v4_0_0.xsd">
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
+
     <groupId>com.mabsisa</groupId>
     <artifactId>Twitter4J</artifactId>
     <packaging>jar</packaging>
@@ -14,17 +15,11 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-        <java.version>1.8</java.version>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>org.twitter4j</groupId>
             <artifactId>twitter4j-stream</artifactId>
-            <version>4.0.6</version>
+            <version>${twitter4j-stream.version}</version>
         </dependency>
     </dependencies>
 
@@ -49,4 +44,8 @@
         </plugins>
     </build>
 
+    <properties>
+        <twitter4j-stream.version>4.0.6</twitter4j-stream.version>
+    </properties>
+
 </project>

activejdbc/pom.xml

@@ -1,5 +1,5 @@
 <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">
+    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>activejdbc</artifactId>
@@ -15,12 +15,6 @@
     </parent>
 
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <version>${junit.version}</version>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.javalite</groupId>
             <artifactId>activejdbc</artifactId>
@@ -133,10 +127,8 @@
     </pluginRepositories>
 
     <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <activejdbc.version>1.4.13</activejdbc.version>
         <environments>development.test,development</environments>
-        <org.slf4j.version>1.7.9</org.slf4j.version>
         <mysql.connector.version>5.1.34</mysql.connector.version>
     </properties>
 

akka-streams/pom.xml

@@ -1,6 +1,6 @@
 <?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">
+    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/README.md

@@ -5,7 +5,6 @@
 - [Ant Colony Optimization](http://www.baeldung.com/java-ant-colony-optimization)
 - [Validating Input With Finite Automata in Java](http://www.baeldung.com/java-finite-automata)
 - [Introduction to Jenetics Library](http://www.baeldung.com/jenetics)
-- [Check If a Number Is Prime in Java](http://www.baeldung.com/java-prime-numbers)
 - [Example of Hill Climbing Algorithm](http://www.baeldung.com/java-hill-climbing-algorithm)
 - [Monte Carlo Tree Search for Tic-Tac-Toe Game](http://www.baeldung.com/java-monte-carlo-tree-search)
 - [String Search Algorithms for Large Texts](http://www.baeldung.com/java-full-text-search-algorithms)
@@ -21,4 +20,6 @@
 - [Create a Sudoku Solver in Java](http://www.baeldung.com/java-sudoku)
 - [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)
 - [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)
-- [Find All Pairs of Numbers in an Array That Add Up to a Given Sum](http://www.baeldung.com/java-algorithm-number-pairs-sum)
+- [Converting Between Roman and Arabic Numerals in Java](http://www.baeldung.com/java-convert-roman-arabic)
+- [Practical Java Examples of the Big O Notation](http://www.baeldung.com/java-algorithm-complexity)
+- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)

algorithms/pom.xml

@@ -1,5 +1,5 @@
 <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">
+    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>algorithms</artifactId>
@@ -79,7 +79,6 @@
     </reporting>
 
     <properties>
-        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
         <lombok.version>1.16.12</lombok.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <tradukisto.version>1.0.1</tradukisto.version>

algorithms/src/main/java/com/baeldung/algorithms/RunAlgorithm.java

@@ -6,7 +6,6 @@
 import com.baeldung.algorithms.ga.ant_colony.AntColonyOptimization;
 import com.baeldung.algorithms.ga.binary.SimpleGeneticAlgorithm;
 import com.baeldung.algorithms.slope_one.SlopeOne;
-import com.baeldung.algorithms.pairsaddupnumber.FindPairs;
 
 public class RunAlgorithm {
 
@@ -39,12 +38,6 @@ public static void main(String[] args) throws InstantiationException, IllegalAcc
 		case 5:
 			System.out.println("Please run the DijkstraAlgorithmTest.");
 			break;
-		case 6:
-			final FindPairs findPairs = new FindPairs();
-			final int[] input = {1, 4, 3, 2, 1, 4, 4, 3, 3};
-			final int sum = 6;
-			findPairs.execute(input, sum);
-			break;
 		default:
 			System.out.println("Unknown option");
 			break;

algorithms/src/main/java/com/baeldung/algorithms/mcts/montecarlo/MonteCarloTreeSearch.java

@@ -10,7 +10,7 @@ public class MonteCarloTreeSearch {
 
     private static final int WIN_SCORE = 10;
     private int level;
-    private int oponent;
+    private int opponent;
 
     public MonteCarloTreeSearch() {
         this.level = 3;
@@ -32,11 +32,11 @@ public Board findNextMove(Board board, int playerNo) {
         long start = System.currentTimeMillis();
         long end = start + 60 * getMillisForCurrentLevel();
 
-        oponent = 3 - playerNo;
+        opponent = 3 - playerNo;
         Tree tree = new Tree();
         Node rootNode = tree.getRoot();
         rootNode.getState().setBoard(board);
-        rootNode.getState().setPlayerNo(oponent);
+        rootNode.getState().setPlayerNo(opponent);
 
         while (System.currentTimeMillis() < end) {
             // Phase 1 - Selection
@@ -93,7 +93,7 @@ private int simulateRandomPlayout(Node node) {
         State tempState = tempNode.getState();
         int boardStatus = tempState.getBoard().checkStatus();
 
-        if (boardStatus == oponent) {
+        if (boardStatus == opponent) {
             tempNode.getParent().getState().setWinScore(Integer.MIN_VALUE);
             return boardStatus;
         }

algorithms/src/main/java/com/baeldung/algorithms/romannumerals/RomanArabicConverter.java

@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.romannumerals;
+
+import java.util.List;
+
+class RomanArabicConverter {
+
+    public static int romanToArabic(String input) {
+        String romanNumeral = input.toUpperCase();
+        int result = 0;
+
+        List<RomanNumeral> romanNumerals = RomanNumeral.getReverseSortedValues();
+
+        int i = 0;
+
+        while ((romanNumeral.length() > 0) && (i < romanNumerals.size())) {
+            RomanNumeral symbol = romanNumerals.get(i);
+            if (romanNumeral.startsWith(symbol.name())) {
+                result += symbol.getValue();
+                romanNumeral = romanNumeral.substring(symbol.name().length());
+            } else {
+                i++;
+            }
+        }
+        if (romanNumeral.length() > 0) {
+            throw new IllegalArgumentException(input + " cannot be converted to a Roman Numeral");
+        }
+
+        return result;
+    }
+
+    public static String arabicToRoman(int number) {
+        if ((number <= 0) || (number > 4000)) {
+            throw new IllegalArgumentException(number + " is not in range (0,4000]");
+        }
+
+        List<RomanNumeral> romanNumerals = RomanNumeral.getReverseSortedValues();
+
+        int i = 0;
+        StringBuilder sb = new StringBuilder();
+
+        while (number > 0 && i < romanNumerals.size()) {
+            RomanNumeral currentSymbol = romanNumerals.get(i);
+            if (currentSymbol.getValue() <= number) {
+                sb.append(currentSymbol.name());
+                number -= currentSymbol.getValue();
+            } else {
+                i++;
+            }
+        }
+        return sb.toString();
+    }
+}

algorithms/src/main/java/com/baeldung/algorithms/romannumerals/RomanNumeral.java

@@ -0,0 +1,26 @@
+package com.baeldung.algorithms.romannumerals;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+enum RomanNumeral {
+    I(1), IV(4), V(5), IX(9), X(10), XL(40), L(50), XC(90), C(100), CD(400), D(500), CM(900), M(1000);
+
+    private int value;
+
+    RomanNumeral(int value) {
+        this.value = value;
+    }
+
+    public int getValue() {
+        return value;
+    }
+
+    public static List<RomanNumeral> getReverseSortedValues() {
+        return Arrays.stream(values())
+          .sorted(Comparator.comparing((RomanNumeral e) -> e.value).reversed())
+          .collect(Collectors.toList());
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/romannumerals/RomanArabicConverterUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.romannumerals;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class RomanArabicConverterUnitTest {
+
+    @Test
+    public void given2018Roman_WhenConvertingToArabic_ThenReturn2018() {
+
+        String roman2018 = "MMXVIII";
+
+        int result = RomanArabicConverter.romanToArabic(roman2018);
+
+        assertThat(result).isEqualTo(2018);
+    }
+
+    @Test
+    public void given1999Arabic_WhenConvertingToRoman_ThenReturnMCMXCIX() {
+
+        int arabic1999 = 1999;
+
+        String result = RomanArabicConverter.arabicToRoman(arabic1999);
+
+        assertThat(result).isEqualTo("MCMXCIX");
+    }
+
+}