LANG-877: Performance improvements for StringEscapeUtils. This fixes #49 from github. Thanks to Fabian Lange.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1666535 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 9 insertions, 8 deletions

diff --git a/src/main/java/org/apache/commons/lang3/CharUtils.java b/src/main/java/org/apache/commons/lang3/CharUtils.java
index 3f19a214e..eb0c2c684 100644
--- a/src/main/java/org/apache/commons/lang3/CharUtils.java
+++ b/src/main/java/org/apache/commons/lang3/CharUtils.java
@@ -31,6 +31,8 @@ public class CharUtils {
     
     private static final String[] CHAR_STRING_ARRAY = new String[128];
     
+    private static final char[] HEX_DIGITS = new char[] {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
+
     /**
      * {@code \u000a} linefeed LF ('\n').
      * 
@@ -350,14 +352,13 @@ public class CharUtils {
      * @return the escaped Unicode string
      */
     public static String unicodeEscaped(final char ch) {
-        if (ch < 0x10) {
-            return "\\u000" + Integer.toHexString(ch);
-        } else if (ch < 0x100) {
-            return "\\u00" + Integer.toHexString(ch);
-        } else if (ch < 0x1000) {
-            return "\\u0" + Integer.toHexString(ch);
-        }
-        return "\\u" + Integer.toHexString(ch);
+        StringBuilder sb = new StringBuilder(6);
+        sb.append("\\u");
+        sb.append(HEX_DIGITS[(ch >> 12) & 15]);
+        sb.append(HEX_DIGITS[(ch >> 8) & 15]);
+        sb.append(HEX_DIGITS[(ch >> 4) & 15]);
+        sb.append(HEX_DIGITS[(ch) & 15]);
+        return sb.toString();
     }
     
     /**