init

.gitignore

@@ -0,0 +1,38 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

pom.xml

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+<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>org.example</groupId>
+  <artifactId>RomanCharConverter</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <name>RomanCharConverter</name>
+  <url>http://maven.apache.org</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

src/main/java/com/tf/romanCharConverter/RomanCharConverter.java

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+package com.tf.romanCharConverter;
+
+import java.util.HashMap;
+
+public class RomanCharConverter {
+
+    private final HashMap<String, Integer> romanToArabic = new HashMap<String, Integer>();
+    public RomanCharConverter() {
+        this.romanToArabic.put("I", 1);
+        this.romanToArabic.put("V", 5);
+        this.romanToArabic.put("X", 10);
+        this.romanToArabic.put("L", 50);
+        this.romanToArabic.put("C", 100);
+        this.romanToArabic.put("D", 500);
+        this.romanToArabic.put("M", 1000);
+        this.romanToArabic.put("A", 5000);
+    }
+
+    public int convert(String romanString) {
+        int result = 0;
+        for (int i = 0; i < romanString.length(); i++) {
+            String romanChar = String.valueOf(romanString.charAt(i));
+
+            if(i < romanString.length() - 1) {
+                String nextRomanChar = String.valueOf(romanString.charAt(i + 1));
+                if(this.romanToArabic.get(romanChar) < this.romanToArabic.get(nextRomanChar)) {
+                    result -= this.romanToArabic.get(romanChar);
+                    continue;
+                }
+            }
+
+            result += this.romanToArabic.get(romanChar);
+
+        }
+        return result;
+    }
+}

src/test/java/com/tf/romanCharConverter/RomanCharConverterTest.java

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+package com.tf.romanCharConverter;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class RomanCharConverterTest {
+    private RomanCharConverter converter;
+
+    @BeforeEach
+    public void setUp() {
+        converter = new RomanCharConverter();
+    }
+
+    @Test
+    public void givenSingleRomanChar_whenConvert_thenArabic(){
+        assertEquals(10, converter.convert("X"));
+        assertEquals(50, converter.convert("L"));
+        assertEquals(100, converter.convert("C"));
+        assertEquals(500, converter.convert("D"));
+        assertEquals(1000, converter.convert("M"));
+        assertEquals(5000, converter.convert("A"));
+    }
+
+    @Test
+    public void givenMultipleRomanChar_whenConvert_thenArabic(){
+        assertEquals(2, converter.convert("II"));
+        assertEquals(20, converter.convert("XX"));
+        assertEquals(200, converter.convert("CC"));
+        assertEquals(2000, converter.convert("MM"));
+        assertEquals(10000, converter.convert("AA"));
+
+        assertEquals(3, converter.convert("III"));
+        assertEquals(30, converter.convert("XXX"));
+        assertEquals(300, converter.convert("CCC"));
+        assertEquals(3000, converter.convert("MMM"));
+        assertEquals(1500, converter.convert("MD"));
+    }
+
+    @Test
+    public void givenMultipleRomanSubstractChar_whenConvert_thenArabic(){
+        assertEquals(4, converter.convert("IV"));
+        assertEquals(9, converter.convert("IX"));
+        assertEquals(40, converter.convert("XL"));
+        assertEquals(90, converter.convert("XC"));
+        assertEquals(400, converter.convert("CD"));
+        assertEquals(900, converter.convert("CM"));
+        assertEquals(14, converter.convert("XIV"));
+    }
+}