Exercise3.4

exercise3.4/RomanNumber.java

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+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package romannumberconversion;
+
+/**
+ *
+ * @author roberta
+ */
+public enum RomanNumber {
+
+    I(1),
+    V(5),
+    X(10),
+    L(50),
+    C(100),
+    D(500),
+    M(1000);
+
+    private final int value;
+
+    RomanNumber(int value) {
+        this.value = value;
+    }
+
+    public int getValue() {
+        return this.value;
+    }
+
+    /**
+     * Devuelve el valor numérico de la letra romana
+     *
+     * @param l
+     * @return
+     */
+    public static int parse(String l) {
+        for (RomanNumber r : RomanNumber.values()) {
+            if (r.toString().equals(l)) {
+                return r.value;
+            }
+        }
+
+        throw new IllegalArgumentException("Not a romand symbol!");
+
+    }
+}

exercise3.4/RomanNumberConversion.java

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+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package romannumberconversion;
+
+/**
+ *
+ * @author roberta
+ */
+public class RomanNumberConversion {
+
+    private String romanNumber;
+
+    public static String decToRoman(int dec) {
+        if (dec <= 0) {
+            return " There isn't zero in Roman number System";
+        }
+        StringBuilder resul = new StringBuilder();
+        while (dec >= 1000) {
+            resul.append("M");
+            dec -= 1000;
+        }
+        while (dec >= 900) {
+            resul.append("CM");
+            dec -= 900;
+        }
+        while (dec >= 500) {
+            resul.append("D");
+            dec -= 500;
+        }
+        while (dec >= 400) {
+            resul.append("CD");
+            dec -= 400;
+        }
+        while (dec >= 100) {
+            resul.append("C");
+            dec -= 100;
+        }
+        while (dec >= 90) {
+            resul.append("XC");
+            dec -= 90;
+        }
+        while (dec >= 50) {
+            resul.append("L");
+            dec -= 50;
+        }
+        while (dec >= 40) {
+            resul.append("XL");
+            dec -= 40;
+        }
+        while (dec >= 10) {
+            resul.append("X");
+            dec -= 10;
+        }
+        while (dec >= 9) {
+            resul.append("IX");
+            dec -= 9;
+        }
+        while (dec >= 5) {
+            resul.append("V");
+            dec -= 5;
+        }
+        while (dec >= 4) {
+            resul.append("IV");
+            dec -= 4;
+        }
+        while (dec >= 1) {
+            resul.append("I");
+            dec -= 1;
+        }
+
+        return resul.toString();
+
+    }
+
+    //	  Returns a string containing the entered Roman numeral in numeral form.
+    public String romanToDec(String s) {
+
+        int resul = 0;
+        int last_digit = 0;
+        int current_digit = 0;
+
+        for (int i = 0; i < s.length(); i++) {
+            current_digit = RomanNumber.parse(s.substring(i, i + 1));
+
+            //This is the tricky part.
+            //If the last number is smaller than the curren number, subtract the last number from the current number
+            //Otherwise, just add the current number. We must also skip the first number from this rule simply because
+            //e.g. someone enters 1799 in which case it would subtract 1 from 7
+            if (last_digit < current_digit && last_digit != 0) {
+                current_digit -= last_digit;
+                resul -= last_digit;
+                resul += current_digit;
+                last_digit = current_digit;
+                current_digit = 0;
+            } else {
+                last_digit = current_digit;
+                resul += current_digit;
+                current_digit = 0;
+            }
+        }
+
+        return String.valueOf(resul);
+
+    }
+
+}

exercise3.4/RomanNumberConversionTest.java

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+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+package romannumberconversion;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ *
+ * @author roberta
+ */
+public class RomanNumberConversionTest {
+
+    public RomanNumberConversionTest() {
+    }
+
+    @BeforeClass
+    public static void setUpClass() {
+    }
+
+    @AfterClass
+    public static void tearDownClass() {
+    }
+
+    @Before
+    public void setUp() {
+    }
+
+    @After
+    public void tearDown() {
+    }
+
+
+
+    /**
+     * Test of decToRoman method, of class RomanNumberConversion.
+     */
+    @Test
+    public void testDecToRoman() {
+        System.out.println("decToRoman");
+        int dec = 5;
+        String expResult = "V";
+        String result = RomanNumberConversion.decToRoman(dec);
+        assertEquals(expResult, result);
+
+    }
+
+    /**
+     * Test of toArabic method, of class RomanNumberConversion.
+     */
+    @Test
+    public void testToArabic() {
+        System.out.println("toArabic");
+        String s = "XXI";
+        RomanNumberConversion instance = new RomanNumberConversion();
+        String expResult = "21";
+        String result = instance.romanToDec(s);
+        assertEquals(expResult, result);
+
+    }
+
+}