StringUtils: Simplify verbose/duplicate and obsolete code constructs

- The 4 replace methods were nearly identical.
- Deprecate String utility, which has a simple one-liner equivalent in the JDK
- Use DatatypeConverter for byte[] to hex. It's less code and even 2-3 times faster than the previous method.

src/java/org/jivesoftware/util/StringUtils.java

@@ -25,6 +25,7 @@ import org.slf4j.LoggerFactory;
 
 import javax.mail.internet.AddressException;
 import javax.mail.internet.InternetAddress;
+import javax.xml.bind.DatatypeConverter;
 import java.net.IDN;
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
@@ -45,7 +46,7 @@ import java.util.concurrent.ConcurrentHashMap;
 /**
  * Utility class to perform common String manipulation algorithms.
  */
-public class StringUtils {
+public final class StringUtils {
 
 	private static final Logger Log = LoggerFactory.getLogger(StringUtils.class);
 
@@ -69,32 +70,11 @@ public class StringUtils {
      * @param oldString the String that should be replaced by newString.
      * @param newString the String that will replace all instances of oldString.
      * @return a String will all instances of oldString replaced by newString.
+     * @deprecated Use {@link String#replaceAll(String, String)}}
      */
+    @Deprecated
     public static String replace(String string, String oldString, String newString) {
-        if (string == null) {
-            return null;
-        }
-        int i = 0;
-        // Make sure that oldString appears at least once before doing any processing.
-        if ((i = string.indexOf(oldString, i)) >= 0) {
-            // Use char []'s, as they are more efficient to deal with.
-            char[] string2 = string.toCharArray();
-            char[] newString2 = newString.toCharArray();
-            int oLength = oldString.length();
-            StringBuilder buf = new StringBuilder(string2.length);
-            buf.append(string2, 0, i).append(newString2);
-            i += oLength;
-            int j = i;
-            // Replace all remaining instances of oldString with newString.
-            while ((i = string.indexOf(oldString, i)) > 0) {
-                buf.append(string2, j, i - j).append(newString2);
-                i += oLength;
-                j = i;
-            }
-            buf.append(string2, j, string2.length - j);
-            return buf.toString();
-        }
-        return string;
+        return replace(string, oldString, newString, new int[1]);
     }
 
     /**
@@ -108,29 +88,7 @@ public class StringUtils {
      */
     public static String replaceIgnoreCase(String line, String oldString,
                                                  String newString) {
-        if (line == null) {
-            return null;
-        }
-        String lcLine = line.toLowerCase();
-        String lcOldString = oldString.toLowerCase();
-        int i = 0;
-        if ((i = lcLine.indexOf(lcOldString, i)) >= 0) {
-            char[] line2 = line.toCharArray();
-            char[] newString2 = newString.toCharArray();
-            int oLength = oldString.length();
-            StringBuilder buf = new StringBuilder(line2.length);
-            buf.append(line2, 0, i).append(newString2);
-            i += oLength;
-            int j = i;
-            while ((i = lcLine.indexOf(lcOldString, i)) > 0) {
-                buf.append(line2, j, i - j).append(newString2);
-                i += oLength;
-                j = i;
-            }
-            buf.append(line2, j, line2.length - j);
-            return buf.toString();
-        }
-        return line;
+        return replaceIgnoreCase(line, oldString, newString, new int[1]);
     }
 
     /**
@@ -146,34 +104,8 @@ public class StringUtils {
      * @return a String will all instances of oldString replaced by newString
      */
     public static String replaceIgnoreCase(String line, String oldString,
-            String newString, int[] count)
-    {
-        if (line == null) {
-            return null;
-        }
-        String lcLine = line.toLowerCase();
-        String lcOldString = oldString.toLowerCase();
-        int i = 0;
-        if ((i = lcLine.indexOf(lcOldString, i)) >= 0) {
-            int counter = 1;
-            char[] line2 = line.toCharArray();
-            char[] newString2 = newString.toCharArray();
-            int oLength = oldString.length();
-            StringBuilder buf = new StringBuilder(line2.length);
-            buf.append(line2, 0, i).append(newString2);
-            i += oLength;
-            int j = i;
-            while ((i = lcLine.indexOf(lcOldString, i)) > 0) {
-                counter++;
-                buf.append(line2, j, i - j).append(newString2);
-                i += oLength;
-                j = i;
-            }
-            buf.append(line2, j, line2.length - j);
-            count[0] = counter;
-            return buf.toString();
-        }
-        return line;
+            String newString, int[] count) {
+        return replace(line, oldString, newString, true, count);
     }
 
     /**
@@ -186,13 +118,19 @@ public class StringUtils {
      * @return a String will all instances of oldString replaced by newString.
      */
     public static String replace(String line, String oldString,
-            String newString, int[] count)
-    {
+            String newString, int[] count) {
+        return replace(line, oldString, newString, false, count);
+    }
+
+    private static String replace(String line, String oldString,
+                                 String newString, boolean ignoreCase, int[] count) {
         if (line == null) {
             return null;
         }
+        String lcLine = ignoreCase ? line.toLowerCase() : line;
+        String lcOldString = ignoreCase ? oldString.toLowerCase() : oldString;
         int i = 0;
-        if ((i = line.indexOf(oldString, i)) >= 0) {
+        if ((i = lcLine.indexOf(lcOldString, i)) >= 0) {
             int counter = 1;
             char[] line2 = line.toCharArray();
             char[] newString2 = newString.toCharArray();
@@ -201,7 +139,7 @@ public class StringUtils {
             buf.append(line2, 0, i).append(newString2);
             i += oLength;
             int j = i;
-            while ((i = line.indexOf(oldString, i)) > 0) {
+            while ((i = lcLine.indexOf(lcOldString, i)) > 0) {
                 counter++;
                 buf.append(line2, j, i - j).append(newString2);
                 i += oLength;
@@ -437,25 +375,12 @@ public class StringUtils {
     /**
      * Turns an array of bytes into a String representing each byte as an
      * unsigned hex number.
-     * <p>
-     * Method by Santeri Paavolainen, Helsinki Finland 1996<br>
-     * (c) Santeri Paavolainen, Helsinki Finland 1996<br>
-     * Distributed under LGPL.</p>
      *
      * @param bytes an array of bytes to convert to a hex-string
      * @return generated hex string
      */
     public static String encodeHex(byte[] bytes) {
-        StringBuilder buf = new StringBuilder(bytes.length * 2);
-        int i;
-
-        for (i = 0; i < bytes.length; i++) {
-            if (((int)bytes[i] & 0xff) < 0x10) {
-                buf.append('0');
-            }
-            buf.append(Long.toString((int)bytes[i] & 0xff, 16));
-        }
-        return buf.toString();
+        return DatatypeConverter.printHexBinary(bytes).toLowerCase();
     }
 
     /**
@@ -466,63 +391,7 @@ public class StringUtils {
      * @return a byte array representing the hex String[
      */
     public static byte[] decodeHex(String hex) {
-        char[] chars = hex.toCharArray();
-        byte[] bytes = new byte[chars.length / 2];
-        int byteCount = 0;
-        for (int i = 0; i < chars.length; i += 2) {
-            int newByte = 0x00;
-            newByte |= hexCharToByte(chars[i]);
-            newByte <<= 4;
-            newByte |= hexCharToByte(chars[i + 1]);
-            bytes[byteCount] = (byte)newByte;
-            byteCount++;
-        }
-        return bytes;
-    }
-
-    /**
-     * Returns the the byte value of a hexadecmical char (0-f). It's assumed
-     * that the hexidecimal chars are lower case as appropriate.
-     *
-     * @param ch a hexedicmal character (0-f)
-     * @return the byte value of the character (0x00-0x0F)
-     */
-    private static byte hexCharToByte(char ch) {
-        switch (ch) {
-            case '0':
-                return 0x00;
-            case '1':
-                return 0x01;
-            case '2':
-                return 0x02;
-            case '3':
-                return 0x03;
-            case '4':
-                return 0x04;
-            case '5':
-                return 0x05;
-            case '6':
-                return 0x06;
-            case '7':
-                return 0x07;
-            case '8':
-                return 0x08;
-            case '9':
-                return 0x09;
-            case 'a':
-                return 0x0A;
-            case 'b':
-                return 0x0B;
-            case 'c':
-                return 0x0C;
-            case 'd':
-                return 0x0D;
-            case 'e':
-                return 0x0E;
-            case 'f':
-                return 0x0F;
-        }
-        return 0x00;
+        return DatatypeConverter.parseHexBinary(hex);
     }
 
     /**
@@ -1224,7 +1093,9 @@ public class StringUtils {
 	 * 
 	 * @param input The source string
 	 * @return The UTF-8 encoding for the given string
+     * @deprecated Use {@code input.getBytes(StandardCharsets.UTF_8)}
 	 */
+    @Deprecated
 	public static byte[] getBytes(String input) {
         return input.getBytes(StandardCharsets.UTF_8);
 	}
@@ -1234,7 +1105,9 @@ public class StringUtils {
 	 * 
 	 * @param input The source byte array
 	 * @return The UTF-8 encoded String for the given byte array
+     * @deprecated Use {@code new String(input, StandardCharsets.UTF_8)}
 	 */
+    @Deprecated
 	public static String getString(byte[] input) {
         return new String(input, StandardCharsets.UTF_8);
 	}

src/test/java/org/jivesoftware/util/StringUtilsTest.java

@@ -28,6 +28,16 @@ public class StringUtilsTest {
 
     }
 
+    @Test
+    public void testStringReplace() {
+        assertEquals(StringUtils.replace("Hello Foo Foo", "Foo", "World"), "Hello World World");
+        assertEquals(StringUtils.replace("Hello Foo foo", "Foo", "World"), "Hello World foo");
+        assertEquals(StringUtils.replaceIgnoreCase("Hello Foo foo", "Foo", "World"), "Hello World World");
+        int[] count = new int[1];
+        assertEquals(StringUtils.replaceIgnoreCase("Hello Foo foo", "Foo", "World", count), "Hello World World");
+        assertEquals(count[0], 2);
+    }
+
 	private void assertValidDomainName(String domain) {
 		assertValidDomainName(domain, domain);
     }