Index: src/test/org/apache/lucene/analysis/TestCharArraySet.java
===================================================================
--- src/test/org/apache/lucene/analysis/TestCharArraySet.java	(revision 618611)
+++ src/test/org/apache/lucene/analysis/TestCharArraySet.java	(working copy)
@@ -18,6 +18,7 @@
  */
 
 import java.io.IOException;
+import java.util.Arrays;
 
 import org.apache.lucene.util.LuceneTestCase;
 import org.apache.lucene.analysis.StopAnalyzer;
@@ -25,12 +26,21 @@
 
 public class TestCharArraySet extends LuceneTestCase
 {
-    public void testRehash() throws Exception {
-      CharArraySet cas = new CharArraySet(0, true);
-      for(int i=0;i<StopAnalyzer.ENGLISH_STOP_WORDS.length;i++)
-        cas.add(StopAnalyzer.ENGLISH_STOP_WORDS[i]);
-      assertEquals(StopAnalyzer.ENGLISH_STOP_WORDS.length, cas.size());
-      for(int i=0;i<StopAnalyzer.ENGLISH_STOP_WORDS.length;i++)
-        assertTrue(cas.contains(StopAnalyzer.ENGLISH_STOP_WORDS[i]));
-    }
+  public void testRehash() throws Exception {
+    CharArraySet cas = new CharArraySet(0, true);
+    for(int i=0;i<StopAnalyzer.ENGLISH_STOP_WORDS.length;i++)
+      cas.add(StopAnalyzer.ENGLISH_STOP_WORDS[i]);
+    assertEquals(StopAnalyzer.ENGLISH_STOP_WORDS.length, cas.size());
+    for(int i=0;i<StopAnalyzer.ENGLISH_STOP_WORDS.length;i++)
+      assertTrue(cas.contains(StopAnalyzer.ENGLISH_STOP_WORDS[i]));
+  }
+
+  public void testNonZeroOffset() {
+    String[] words={"Hello","World","this","is","a","test"};
+    char[] findme="xthisy".toCharArray();   
+    CharArraySet set=new CharArraySet(10,true);
+    set.addAll(Arrays.asList(words));
+    assertTrue(set.contains(findme, 1, 4));
+    assertTrue(set.contains(new String(findme,1,4)));
+  }
 }
Index: src/java/org/apache/lucene/analysis/CharArraySet.java
===================================================================
--- src/java/org/apache/lucene/analysis/CharArraySet.java	(revision 618611)
+++ src/java/org/apache/lucene/analysis/CharArraySet.java	(working copy)
@@ -66,7 +66,7 @@
   }
 
   private int getSlot(char[] text, int off, int len) {
-    int code = getHashCode(text, len);
+    int code = getHashCode(text, off, len);
     int pos = code & (entries.length-1);
     char[] text2 = entries[pos];
     if (text2 != null && !equals(text, off, len, text2)) {
@@ -175,14 +175,15 @@
     }
   }
   
-  private int getHashCode(char[] text, int len) {
+  private int getHashCode(char[] text, int offset, int len) {
     int code = 0;
+    final int stop = offset + len;
     if (ignoreCase) {
-      for (int i=0; i<len; i++) {
+      for (int i=offset; i<stop; i++) {
         code = code*31 + Character.toLowerCase(text[i]);
       }
     } else {
-      for (int i=0; i<len; i++) {
+      for (int i=offset; i<stop; i++) {
         code = code*31 + text[i];
       }
     }