Updates for BAEL-7496 (#16150)

* Moved vigenere cipher code to a new module * New test case for encoding and decoding together
2024-03-21 05:34:48 +00:00
parent 1d289c30b9
commit 30a5cddce0
4 changed files with 37 additions and 7 deletions
@@ -0,0 +1,69 @@
+package com.baeldung.algorithms.vigenere;
+
+public class VigenereCipher {
+    private final String characters;
+
+    public VigenereCipher() {
+        this("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
+    }
+
+    public VigenereCipher(String characters) {
+        this.characters = characters;
+    }
+
+    public String encode(String input, String key) {
+        String result = "";
+
+        int keyPosition = 0;
+        for (char c : input.toCharArray()) {
+            char k = key.charAt(keyPosition % key.length());
+
+            int charIndex = characters.indexOf(c);
+            int keyIndex = characters.indexOf(k);
+
+            if (charIndex >= 0) {
+                if (keyIndex >= 0) {
+                    int newCharIndex = (charIndex + keyIndex + 1) % characters.length();
+                    c = characters.charAt(newCharIndex);
+
+                }
+
+                keyPosition++;
+            }
+
+            result += c;
+        }
+
+        return result;
+    }
+
+    public String decode(String input, String key) {
+        String result = "";
+
+        int keyPosition = 0;
+        for (char c : input.toCharArray()) {
+            char k = key.charAt(keyPosition % key.length());
+
+            int charIndex = characters.indexOf(c);
+            int keyIndex = characters.indexOf(k);
+
+            if (charIndex >= 0) {
+                if (keyIndex >= 0) {
+                    int newCharIndex = charIndex - keyIndex - 1;
+                    if (newCharIndex < 0) {
+                        newCharIndex = characters.length() + newCharIndex;
+                    }
+                    c = characters.charAt(newCharIndex);
+
+                }
+
+                keyPosition++;
+            }
+
+            result += c;
+        }
+
+        return result;
+    }
+
+}
@@ -0,0 +1,76 @@
+package com.baeldung.algorithms.vigenere;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class VigenereCipherUnitTest {
+
+    @Test
+    void encodeBaeldung() {
+        VigenereCipher cipher = new VigenereCipher();
+        String output = cipher.encode("BAELDUNG", "HELLO");
+
+        Assertions.assertEquals("JFQXSCSS", output);
+    }
+
+    @Test
+    void encodeBaeldungMixedCharacters() {
+        VigenereCipher cipher = new VigenereCipher("JQFVHPWORZSLNMKYCGBUXIEDTA");
+        String output = cipher.encode("BAELDUNG", "HELLO");
+
+        Assertions.assertEquals("DERDPTZV", output);
+    }
+
+    @Test
+    void encodeArticleTitle() {
+        VigenereCipher cipher = new VigenereCipher();
+        String output = cipher.encode("VIGENERE CIPHER IN JAVA", "BAELDUNG");
+
+        Assertions.assertEquals("XJLQRZFL EJUTIM WU LBAM", output);
+    }
+
+    @Test
+    void encodeArticleTitleMoreCharacters() {
+        VigenereCipher cipher = new VigenereCipher("ABCDEFGHIJKLMNOPQRSTUVWXYZ ");
+        String output = cipher.encode("VIGENERE CIPHER IN JAVA", "BAELDUNG");
+
+        Assertions.assertEquals("XJLQRZELBDNALZEGKOEVEPO", output);
+    }
+
+    @Test
+    void decodeBaeldung() {
+        VigenereCipher cipher = new VigenereCipher();
+        String output = cipher.decode("JFQXSCSS", "HELLO");
+
+        Assertions.assertEquals("BAELDUNG", output);
+    }
+
+    @Test
+    void decodeBaeldungMixedCharacters() {
+        VigenereCipher cipher = new VigenereCipher("JQFVHPWORZSLNMKYCGBUXIEDTA");
+        String output = cipher.decode("DERDPTZV", "HELLO");
+
+        Assertions.assertEquals("BAELDUNG", output);
+    }
+
+    @Test
+    void decodeArticleTitleMoreCharacters() {
+        VigenereCipher cipher = new VigenereCipher("ABCDEFGHIJKLMNOPQRSTUVWXYZ ");
+        String output = cipher.decode("XJLQRZELBDNALZEGKOEVEPO", "BAELDUNG");
+
+        Assertions.assertEquals("VIGENERE CIPHER IN JAVA", output);
+    }
+
+    @Test
+    void encodeDecodeBaeldung() {
+        VigenereCipher cipher = new VigenereCipher();
+
+        String input = "BAELDUNG";
+        String key = "HELLO";
+
+        String encoded = cipher.encode(input, key);
+        String decoded = cipher.decode(encoded, key);
+
+        Assertions.assertEquals(input, decoded);
+    }
+}