Java Hex to String Conversion with Encoding Handling

Accurate hexadecimal conversion requires proper handling of character encodings. Below are enhanced methods with encoding management capabilities.

Method 1: Encoding-Aware Conversion

 public static String hexToString(String hex) {
    StringBuilder output = new StringBuilder();
    for (int i = 0; i < hex.length(); i += 2) {
        String str = hex.substring(i, i + 2);
        output.append((char) Integer.parseInt(str, 16));
    }
    return output.toString();
}

Enhanced version accepts charset parameter. Converts hex pairs to byte array first, then applies specified encoding. Supports UTF-8, ISO-8859-1, etc.

Method 2: BigInteger with Custom Encoding

 public static String hexToText(String hex, Charset charset) {
    byte[] bytes = new BigInteger(hex, 16).toByteArray();
    return new String(bytes, charset);
} 

Modified to accept charset parameter. Handles leading zero bytes automatically. Suitable for multi-byte encodings like UTF-16.

Critical Implementation Details

• Encoding specification: Always explicitly define charset (e.g., StandardCharsets.UTF_8)
• Byte order marks: Handle BOM manually for UTF-16/UTF-32 encodings
• Error handling: Use try-catch for UnsupportedEncodingException
• Binary safety: For raw byte data, use ISO-8859-1 encoding

Encoding Usage Examples

 // UTF-8 for multilingual text
hexToString("4a617661", StandardCharsets.UTF_8); // Returns "Java"

// ISO-8859-1 for byte preservation
hexToText("c0ff", StandardCharsets.ISO_8859_1); // Returns 0xC0 0xFF as characters

// UTF-16BE for wide-character encoding
hexToString("004a006100760061", StandardCharsets.UTF_16BE); // "Java" 

Test with encoding-specific values: "00a3" (£ in ISO-8859-1 vs "c2a3" in UTF-8). Performance tip: Reuse Charset objects for repeated conversions.

Common Java Character Encodings Reference

Note: Always prefer StandardCharsets constants over string names for type safety. For Windows legacy encodings, use the exact charset name with Charset.forName().