Added HexToAscii example.

core-java/src/main/java/com/baeldung/hextToAscii/HexToAscii.java

@@ -0,0 +1,43 @@
+package com.baeldung.hexToAscii;
+
+public class HexToAscii {
+
+    @Test
+    public static void whenHexToAscii() {
+
+        String asciiString = "http://www.baeldung.com/jackson-serialize-dates";
+        String hexEquivalent = "687474703a2f2f7777772e6261656c64756e672e636f6d2f6a61636b736f6e2d73657269616c697a652d6461746573";
+
+        assertEquals(asciiString, hexToAscii(hexEquivalent));
+    }
+
+    @Test
+    public static void whenAsciiToHex() {
+
+        String asciiString = "http://www.baeldung.com/jackson-serialize-dates";
+        String hexEquivalent = "687474703a2f2f7777772e6261656c64756e672e636f6d2f6a61636b736f6e2d73657269616c697a652d6461746573";
+
+        assertEquals(hexEquivalent, asciiToHex(asciiString));
+    }
+
+    private static String asciiToHex(String asciiStr) {
+
+        char[] chars = asciiStr.toCharArray();
+        StringBuilder hex = new StringBuilder();
+        for (char ch : chars) {
+            hex.append(Integer.toHexString((int) ch));
+        }
+
+        return hex.toString();
+    }
+
+    private static String hexToASCII(String hexStr) {
+
+        StringBuilder output = new StringBuilder("");
+        for (int i = 0; i < hexStr.length(); i += 2) {
+            String str = hexStr.substring(i, i + 2);
+            output.append((char) Integer.parseInt(str, 16));
+        }
+        return output.toString();
+    }
+}