Added update(char[]) to UnionImpl and unit tests.

src/main/java/com/yahoo/sketches/theta/Union.java

@@ -57,6 +57,10 @@ public interface Union {
    * The string is converted to a byte array using UTF8 encoding. 
    * If the string is null or empty no update attempt is made and the method returns.
    * 
+   * <p>Note: this will not produce the same output hash values as the {@link #update(char[])} 
+   * method and will generally be a little slower depending on the complexity of the UTF8 encoding.
+   * </p>
+   * 
    * @param datum The given String.
    */
   void update(String datum);
@@ -77,6 +81,17 @@ public interface Union {
    */
   void update(int[] data);
 
+  /**
+   * Present this union with the given char array. 
+   * If the char array is null or empty no update attempt is made and the method returns.
+   * 
+   * <p>Note: this will not produce the same output hash values as the {@link #update(String)} 
+   * method but will be a little faster as it avoids the complexity of the UTF8 encoding.</p>
+   * 
+   * @param data The given char array.
+   */
+  void update(char[] data);
+
   /**
    * Present this union with the given long array. 
    * If the long array is null or empty no update attempt is made and the method returns.

src/main/java/com/yahoo/sketches/theta/UnionImpl.java

@@ -253,6 +253,11 @@ public void update(byte[] data) {
     gadget_.update(data);
   }
 
+  @Override
+  public void update(char[] data) {
+    gadget_.update(data);
+  }
+
   @Override
   public void update(int[] data) {
     gadget_.update(data);

src/main/java/com/yahoo/sketches/theta/UpdateSketch.java

@@ -150,6 +150,10 @@ public UpdateReturnState update(double datum) {
    * The string is converted to a byte array using UTF8 encoding. 
    * If the string is null or empty no update attempt is made and the method returns.
    * 
+   * <p>Note: this will not produce the same output hash values as the {@link #update(char[])} 
+   * method and will generally be a little slower depending on the complexity of the UTF8 encoding.
+   * </p>
+   * 
    * @param datum The given String.
    * @return 
    * <a href="{@docRoot}/resources/dictionary.html#updateReturnState">See Update Return State</a>
@@ -181,6 +185,9 @@ public UpdateReturnState update(byte[] data) {
    * Present this sketch with the given char array. 
    * If the char array is null or empty no update attempt is made and the method returns.
    * 
+   * <p>Note: this will not produce the same output hash values as the {@link #update(String)} 
+   * method but will be a little faster as it avoids the complexity of the UTF8 encoding.</p>
+   * 
    * @param data The given char array.
    * @return 
    * <a href="{@docRoot}/resources/dictionary.html#updateReturnState">See Update Return State</a>

src/test/java/com/yahoo/sketches/theta/HeapUnionTest.java

@@ -497,38 +497,49 @@ public void checkPrimitiveUpdates() {
     int k = 32;
     Union union = Sketches.setOperationBuilder().buildUnion(k);
 
-    union.update(1L);
-    union.update(1.5); //#1 double
+    union.update(1L);   //#1 long
+    union.update(1.5);  //#2 double
     union.update(0.0);
-    union.update(-0.0);
+    union.update(-0.0); //#3 double
     String s = null;
-    union.update(s); //null string
+    union.update(s);    //null string
     s = "";
-    union.update(s); //empty string
+    union.update(s);    //empty string
     s = "String";
-    union.update(s); //#2 actual string
+    union.update(s);    //#4 actual string
+
     byte[] byteArr = null;
     union.update(byteArr); //null byte[]
     byteArr = new byte[0];
     union.update(byteArr); //empty byte[]
     byteArr = "Byte Array".getBytes();
-    union.update(byteArr); //#3 actual byte[]
+    union.update(byteArr); //#5 actual byte[]
+
+    char[] charArr = null;
+    union.update(charArr); //null char[]
+    charArr = new char[0];
+    union.update(charArr); //empty char[]
+    charArr = "String".toCharArray();
+    union.update(charArr); //#6 actual char[]
+
     int[] intArr = null;
     union.update(intArr); //null int[]
     intArr = new int[0];
     union.update(intArr); //empty int[]
     int[] intArr2 = { 1, 2, 3, 4, 5 };
-    union.update(intArr2); //#4 actual int[]
+    union.update(intArr2); //#7 actual int[]
+
     long[] longArr = null;
     union.update(longArr); //null long[]
     longArr = new long[0];
     union.update(longArr); //empty long[]
     long[] longArr2 = { 6, 7, 8, 9 };
-    union.update(longArr2); //#5 actual long[]
+    union.update(longArr2); //#8 actual long[]
+
     CompactSketch comp = union.getResult();
     double est = comp.getEstimate();
     boolean empty = comp.isEmpty();
-    assertEquals(est, 7.0, 0.0);
+    assertEquals(est, 8.0, 0.0);
     assertFalse(empty);
   }
 

src/test/java/com/yahoo/sketches/theta/UpdateSketchTest.java

@@ -23,36 +23,47 @@ public class UpdateSketchTest {
   public void checkOtherUpdates() {
     int k = 512;
     UpdateSketch sk1 = UpdateSketch.builder().build(k);
-    sk1.update(1.5); //#1 double
+    sk1.update(1L);   //#1 long
+    sk1.update(1.5);  //#2 double
     sk1.update(0.0);
-    sk1.update(-0.0);
+    sk1.update(-0.0); //#3 double 
     String s = null;
-    sk1.update(s); //null string
+    sk1.update(s);    //null string
     s = "";
-    sk1.update(s); //empty string
+    sk1.update(s);    //empty string
     s = "String";
-    sk1.update(s); //#2 actual string
+    sk1.update(s);    //#4 actual string
+
     byte[] byteArr = null;
     sk1.update(byteArr); //null byte[]
     byteArr = new byte[0];
     sk1.update(byteArr); //empty byte[]
     byteArr = "Byte Array".getBytes();
-    sk1.update(byteArr); //#3 actual byte[]
+    sk1.update(byteArr); //#5 actual byte[]
+
+    char[] charArr = null;
+    sk1.update(charArr); //null char[]
+    charArr = new char[0];
+    sk1.update(charArr); //empty char[]
+    charArr = "String".toCharArray();
+    sk1.update(charArr); //#6 actual char[]
+
     int[] intArr = null;
     sk1.update(intArr); //null int[]
     intArr = new int[0];
     sk1.update(intArr); //empty int[]
     int[] intArr2 = { 1, 2, 3, 4, 5 };
-    sk1.update(intArr2); //#4 actual int[]
+    sk1.update(intArr2); //#7 actual int[]
+
     long[] longArr = null;
     sk1.update(longArr); //null long[]
     longArr = new long[0];
     sk1.update(longArr); //empty long[]
     long[] longArr2 = { 6, 7, 8, 9 };
-    sk1.update(longArr2); //#5 actual long[]
+    sk1.update(longArr2); //#8 actual long[]
 
     double est = sk1.getEstimate();
-    assertEquals(est, 6.0, 0.0);
+    assertEquals(est, 8.0, 0.0);
   }
 
   @Test