Consolidate HexTool methods and add more tests

src/main/java/tools/HexTool.java

@@ -22,30 +22,44 @@
 package tools;
 
 import constants.string.CharsetConstants;
-import io.netty.buffer.ByteBufUtil;
 
 import java.util.HexFormat;
 
-// TODO: use HexFormat from Java 17
+/**
+ * Handles converting back and forth from byte arrays to hex strings.
+ */
 public class HexTool {
 
     /**
-     * Convert a byte array to its hex string representation.
-     * Each byte value is equivalent to two hex characters delimited by a space.
+     * Convert a byte array to its hex string representation (upper case).
+     * Each byte value is converted to two hex characters delimited by a space.
      *
      * @param bytes Byte array to convert to a hex string.
      *              Example: {1, 16, 127, -1} is converted to "01 F0 7F FF"
      * @return The hex string
      */
-    public static String toString(byte[] bytes) {
+    public static String toHexString(byte[] bytes) {
         return HexFormat.ofDelimiter(" ").withUpperCase().formatHex(bytes);
     }
 
     /**
-     * Convert a hex string to its byte array representation. Two consecutive hex characters are equivalent to one byte.
+     * Convert a byte array to its hex string representation (upper case).
+     * Like {@link #toHexString(byte[]) HexTool.toString}, but with no space delimiter.
      *
-     * @param hexString Hex string to convert to bytes. Hex character pairs may be delimited by a space or not (compact)
+     * @return The compact hex string
+     */
+    public static String toCompactHexString(byte[] bytes) {
+        return HexFormat.of().withUpperCase().formatHex(bytes);
+    }
+
+    /**
+     * Convert a hex string to its byte array representation. Two consecutive hex characters are converted to one byte.
+     *
+     * @param hexString Hex string to convert to bytes. May be lower or upper case, and hex character pairs may be
+     *                  delimited by a space or not.
      *                  Example: "01 10 7F FF" is converted to {1, 16, 127, -1}.
+     *                  The following hex strings are considered identical and are converted to the same byte array:
+     *                  "01 10 7F FF", "01107FFF", "01 10 7f ff", "01107fff"
      * @return The byte array
      */
     public static byte[] toBytes(String hexString) {
@@ -57,27 +71,19 @@ public class HexTool {
     }
 
     public static String toStringFromAscii(final byte[] bytes) {
-        byte[] ret = new byte[bytes.length];
-        for (int x = 0; x < bytes.length; x++) {
-            if (bytes[x] < 32 && bytes[x] >= 0) {
-                ret[x] = '.';
+        byte[] filteredBytes = new byte[bytes.length];
+        for (int i = 0; i < bytes.length; i++) {
+            if (isSpecialCharacter(bytes[i])) {
+                filteredBytes[i] = '.';
             } else {
-                int chr = ((short) bytes[x]) & 0xFF;
-                ret[x] = (byte) chr;
+                filteredBytes[i] = (byte) (bytes[i] & 0xFF);
             }
         }
 
-        return new String(ret, CharsetConstants.CHARSET);
+        return new String(filteredBytes, CharsetConstants.CHARSET);
     }
 
-    /**
-     * Get upper case hex dump
-     */
-    public static String bytesToHex(byte[] bytes) {
-        return ByteBufUtil.hexDump(bytes).toUpperCase();
-    }
-
-    public static byte[] hexToBytes(String hex) {
-        return ByteBufUtil.decodeHexDump(hex);
+    private static boolean isSpecialCharacter(byte asciiCode) {
+        return asciiCode >= 0 && asciiCode <= 31;
     }
 }