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(char l) {
+        switch (l) {
+            case 'I':
+                return I.value;
+            case 'V':
+                return V.value;
+            case 'X':
+                return X.value;
+            case 'L':
+                return L.value;
+            case 'C':
+                return C.value;
+            case 'D':
+                return D.value;
+            case 'M':
+                return M.value;
+            default:
+                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";
+        }
+        String resul = "";
+        while (dec >= 1000) {
+            resul += "M";
+            dec -= 1000;
+        }
+        while (dec >= 900) {
+            resul += "CM";
+            dec -= 900;
+        }
+        while (dec >= 500) {
+            resul += "D";
+            dec -= 500;
+        }
+        while (dec >= 400) {
+            resul += "CD";
+            dec -= 400;
+        }
+        while (dec >= 100) {
+            resul += "C";
+            dec -= 100;
+        }
+        while (dec >= 90) {
+            resul += "XC";
+            dec -= 90;
+        }
+        while (dec >= 50) {
+            resul += "L";
+            dec -= 50;
+        }
+        while (dec >= 40) {
+            resul += "XL";
+            dec -= 40;
+        }
+        while (dec >= 10) {
+            resul += "X";
+            dec -= 10;
+        }
+        while (dec >= 9) {
+            resul += "IX";
+            dec -= 9;
+        }
+        while (dec >= 5) {
+            resul += "V";
+            dec -= 5;
+        }
+        while (dec >= 4) {
+            resul += "IV";
+            dec -= 4;
+        }
+        while (dec >= 1) {
+            resul += "I";
+            dec -= 1;
+        }
+
+        return resul;
+
+    }
+      //	  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.charAt(i));
+
+
+				//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);
+        // TODO review the generated test code and remove the default call to fail.
+        //fail("The test case is a prototype.");
+    }
+
+    /**
+     * 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);
+        // TODO review the generated test code and remove the default call to fail.
+       // fail("The test case is a prototype.");
+    }
+
+}