ARROW-3923: [Java] JDBC Time Fetches Without Timezone

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrow.java

@@ -179,13 +179,12 @@ public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, BaseAllocator all
    * For the given JDBC {@link ResultSet}, fetch the data from Relational DB and convert it to Arrow objects.
    *
    * @param resultSet ResultSet to use to fetch the data from underlying database
-   * @param calendar  Calendar instance to use for Date, Time and Timestamp datasets.
+   * @param calendar  Calendar instance to use for Date, Time and Timestamp datasets, or <code>null</code> if none.
    * @return Arrow Data Objects {@link VectorSchemaRoot}
    * @throws SQLException on error
    */
   public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, Calendar calendar) throws SQLException, IOException {
     Preconditions.checkNotNull(resultSet, "JDBC ResultSet object can not be null");
-    Preconditions.checkNotNull(calendar, "Calendar object can not be null");
 
     return sqlToArrow(resultSet, new JdbcToArrowConfig(new RootAllocator(Integer.MAX_VALUE), calendar));
   }
@@ -195,15 +194,14 @@ public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, Calendar calendar
    *
    * @param resultSet ResultSet to use to fetch the data from underlying database
    * @param allocator Memory allocator to use.
-   * @param calendar  Calendar instance to use for Date, Time and Timestamp datasets.
+   * @param calendar  Calendar instance to use for Date, Time and Timestamp datasets, or <code>null</code> if none.
    * @return Arrow Data Objects {@link VectorSchemaRoot}
    * @throws SQLException on error
    */
   public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, BaseAllocator allocator, Calendar calendar)
       throws SQLException, IOException {
     Preconditions.checkNotNull(resultSet, "JDBC ResultSet object can not be null");
     Preconditions.checkNotNull(allocator, "Memory Allocator object can not be null");
-    Preconditions.checkNotNull(calendar, "Calendar object can not be null");
 
     return sqlToArrow(resultSet, new JdbcToArrowConfig(allocator, calendar));
   }

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrowConfig.java

@@ -48,15 +48,15 @@ public final class JdbcToArrowConfig {
    */
   JdbcToArrowConfig(BaseAllocator allocator, Calendar calendar) {
     Preconditions.checkNotNull(allocator, "Memory allocator cannot be null");
-    Preconditions.checkNotNull(calendar, "Calendar object can not be null");
 
     this.allocator = allocator;
     this.calendar = calendar;
   }
 
   /**
    * The calendar to use when defining Arrow Timestamp fields
-   * and retrieving time-based fields from the database.
+   * and retrieving {@link Date}, {@link Time}, or {@link Timestamp}
+   * data types from the {@link ResultSet}, or <code>null</code> if not converting.
    * @return the calendar.
    */
   public Calendar getCalendar() {

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrowConfigBuilder.java

@@ -32,7 +32,7 @@ public class JdbcToArrowConfigBuilder {
 
   /**
    * Default constructor for the <code>JdbcToArrowConfigBuilder}</code>.
-   * Use the setter methods for the allocator and calendar; both must be
+   * Use the setter methods for the allocator and calendar; the allocator must be
    * set.  Otherwise, {@link #build()} will throw a {@link NullPointerException}.
    */
   public JdbcToArrowConfigBuilder() {
@@ -41,9 +41,9 @@ public JdbcToArrowConfigBuilder() {
   }
 
   /**
-   * Constructor for the <code>JdbcToArrowConfigBuilder</code>.  Both the
-   * allocator and calendar are required.  A {@link NullPointerException}
-   * will be thrown if one of the arguments is <code>null</code>.
+   * Constructor for the <code>JdbcToArrowConfigBuilder</code>.  The
+   * allocator is required, and a {@link NullPointerException}
+   * will be thrown if it is <code>null</code>.
    * <p>
    * The allocator is used to construct Arrow vectors from the JDBC ResultSet.
    * The calendar is used to determine the time zone of {@link java.sql.Timestamp}
@@ -59,7 +59,6 @@ public JdbcToArrowConfigBuilder(BaseAllocator allocator, Calendar calendar) {
     this();
 
     Preconditions.checkNotNull(allocator, "Memory allocator cannot be null");
-    Preconditions.checkNotNull(calendar, "Calendar object can not be null");
 
     this.allocator = allocator;
     this.calendar = calendar;
@@ -82,10 +81,8 @@ public JdbcToArrowConfigBuilder setAllocator(BaseAllocator allocator) {
    * Arrow schema, and reading time-based fields from the JDBC <code>ResultSet</code>.
    *
    * @param calendar the calendar to set.
-   * @exception NullPointerExeption if <code>calendar</code> is <code>null</code>.
    */
   public JdbcToArrowConfigBuilder setCalendar(Calendar calendar) {
-    Preconditions.checkNotNull(calendar, "Calendar object can not be null");
     this.calendar = calendar;
     return this;
   }

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrowUtils.java

@@ -240,15 +240,15 @@ private static void allocateVectors(VectorSchemaRoot root, int size) {
    *
    * @param rs       ResultSet to use to fetch the data from underlying database
    * @param root     Arrow {@link VectorSchemaRoot} object to populate
-   * @param calendar The calendar to use when reading time-based data.
+   * @param calendar The calendar to use when reading {@link Date}, {@link Time}, or {@link Timestamp}
+   *                 data types from the {@link ResultSet}, or <code>null</code> if not converting.
    * @throws SQLException on error
    */
   public static void jdbcToArrowVectors(ResultSet rs, VectorSchemaRoot root, Calendar calendar)
       throws SQLException, IOException {
 
     Preconditions.checkNotNull(rs, "JDBC ResultSet object can't be null");
-    Preconditions.checkNotNull(root, "Vector Schema cannot be null");
-    Preconditions.checkNotNull(calendar, "Calendar object can't be null");
+    Preconditions.checkNotNull(root, "JDBC ResultSet object can't be null");
 
     jdbcToArrowVectors(rs, root, new JdbcToArrowConfig(new RootAllocator(0), calendar));
   }
@@ -274,6 +274,8 @@ public static void jdbcToArrowVectors(ResultSet rs, VectorSchemaRoot root, JdbcT
 
     allocateVectors(root, DEFAULT_BUFFER_SIZE);
 
+    final Calendar calendar = config.getCalendar();
+
     int rowCount = 0;
     while (rs.next()) {
       for (int i = 1; i <= columnCount; i++) {
@@ -324,17 +326,35 @@ public static void jdbcToArrowVectors(ResultSet rs, VectorSchemaRoot root, JdbcT
                     rs.getString(i), !rs.wasNull(), rowCount);
             break;
           case Types.DATE:
-            updateVector((DateMilliVector) root.getVector(columnName),
-                    rs.getDate(i, config.getCalendar()), !rs.wasNull(), rowCount);
+            final Date date;
+            if (calendar != null) {
+              date = rs.getDate(i, calendar);
+            } else {
+              date = rs.getDate(i);
+            }
+
+            updateVector((DateMilliVector) root.getVector(columnName), date, !rs.wasNull(), rowCount);
             break;
           case Types.TIME:
-            updateVector((TimeMilliVector) root.getVector(columnName),
-                    rs.getTime(i, config.getCalendar()), !rs.wasNull(), rowCount);
+            final Time time;
+            if (calendar != null) {
+              time = rs.getTime(i, calendar);
+            } else {
+              time = rs.getTime(i);
+            }
+
+            updateVector((TimeMilliVector) root.getVector(columnName), time, !rs.wasNull(), rowCount);
             break;
           case Types.TIMESTAMP:
+            final Timestamp ts;
+            if (calendar != null) {
+              ts = rs.getTimestamp(i, calendar);
+            } else {
+              ts = rs.getTimestamp(i);
+            }
+
             // TODO: Need to handle precision such as milli, micro, nano
-            updateVector((TimeStampVector) root.getVector(columnName),
-                    rs.getTimestamp(i, config.getCalendar()), !rs.wasNull(), rowCount);
+            updateVector((TimeStampVector) root.getVector(columnName), ts, !rs.wasNull(), rowCount);
             break;
           case Types.BINARY:
           case Types.VARBINARY:

java/adapter/jdbc/src/test/java/org/apache/arrow/adapter/jdbc/JdbcToArrowConfigTest.java

@@ -42,14 +42,16 @@ public void testBuilderNullArguments() {
     new JdbcToArrowConfigBuilder(null, null);
   }
 
-  @Test(expected = NullPointerException.class)
   public void testConfigNullCalendar() {
-    new JdbcToArrowConfig(allocator, null);
+    JdbcToArrowConfig config = new JdbcToArrowConfig(allocator, null);
+    assertNull(config.getCalendar());
   }
 
-  @Test(expected = NullPointerException.class)
+  @Test
   public void testBuilderNullCalendar() {
-    new JdbcToArrowConfigBuilder(allocator, null);
+    JdbcToArrowConfigBuilder builder = new JdbcToArrowConfigBuilder(allocator, null);
+    JdbcToArrowConfig config = builder.build();
+    assertNull(config.getCalendar());
   }
 
   @Test(expected = NullPointerException.class)
@@ -68,10 +70,11 @@ public void testSetNullAllocator() {
     builder.setAllocator(null);
   }
 
-  @Test(expected = NullPointerException.class)
+  @Test
   public void testSetNullCalendar() {
     JdbcToArrowConfigBuilder builder = new JdbcToArrowConfigBuilder(allocator, calendar);
-    builder.setCalendar(null);
+    JdbcToArrowConfig config = builder.setCalendar(null).build();
+    assertNull(config.getCalendar());
   }
 
   @Test