Do not call substring() twice in StringUtils.trim()

h2/src/main/org/h2/util/StringUtils.java

@@ -845,23 +845,20 @@ public class StringUtils {
      */
     public static String trim(String s, boolean leading, boolean trailing,
             String sp) {
-        char space = (sp == null || sp.length() < 1) ? ' ' : sp.charAt(0);
+        char space = sp == null || sp.isEmpty() ? ' ' : sp.charAt(0);
+        int begin = 0, end = s.length();
         if (leading) {
-            int len = s.length(), i = 0;
-            while (i < len && s.charAt(i) == space) {
-                i++;
+            while (begin < end && s.charAt(begin) == space) {
+                begin++;
             }
-            s = (i == 0) ? s : s.substring(i);
         }
         if (trailing) {
-            int endIndex = s.length() - 1;
-            int i = endIndex;
-            while (i >= 0 && s.charAt(i) == space) {
-                i--;
+            while (end > begin && s.charAt(end - 1) == space) {
+                end--;
             }
-            s = i == endIndex ? s : s.substring(0, i + 1);
         }
-        return s;
+        // substring() returns self if start == 0 && end == length()
+        return s.substring(begin, end);
     }
 
     /**

h2/src/test/org/h2/test/unit/TestStringUtils.java

@@ -39,6 +39,7 @@ public class TestStringUtils extends TestBase {
         testURL();
         testPad();
         testReplaceAll();
+        testTrim();
     }
 
     private void testHex() {
@@ -226,4 +227,28 @@ public class TestStringUtils extends TestBase {
                 StringUtils.replaceAll("abcabcabc", "aBc", ""));
     }
 
+    private void testTrim() {
+        assertEquals("a a",
+                StringUtils.trim("a a", true, true, null));
+        assertEquals("  a a  ",
+                StringUtils.trim("  a a  ", false, false, null));
+        assertEquals("  a a",
+                StringUtils.trim("  a a  ", false, true, null));
+        assertEquals("a a  ",
+                StringUtils.trim("  a a  ", true, false, null));
+        assertEquals("a a",
+                StringUtils.trim("  a a  ", true, true, null));
+        assertEquals("a a",
+                StringUtils.trim("  a a  ", true, true, ""));
+        assertEquals("zzbbzz",
+                StringUtils.trim("zzbbzz", false, false, "z"));
+        assertEquals("zzbb",
+                StringUtils.trim("zzbbzz", false, true, "z"));
+        assertEquals("bbzz",
+                StringUtils.trim("zzbbzz", true, false, "z"));
+        assertEquals("bb",
+                StringUtils.trim("zzbbzz", true, true, "z"));
+    }
+
+
 }