apacheGH-37728: [Java] Add methods to get an Iterable for a ValueVector

* Added a method to get an Iterator for a ValueVector
* Added a method to get an Iterable for a ValueVector
* The Iterator/Iterable are typed to Object

java/dataset/pom.xml

@@ -150,6 +150,12 @@
       <version>2.15.1</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.hamcrest</groupId>
+      <artifactId>hamcrest</artifactId>
+      <version>2.2</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
   <build>
     <resources>

java/dataset/src/test/java/org/apache/arrow/dataset/substrait/TestAceroSubstraitConsumer.java

@@ -17,6 +17,7 @@
 
 package org.apache.arrow.dataset.substrait;
 
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
@@ -45,6 +46,9 @@
 import org.apache.arrow.vector.types.pojo.Field;
 import org.apache.arrow.vector.types.pojo.FieldType;
 import org.apache.arrow.vector.types.pojo.Schema;
+import org.apache.arrow.vector.util.Text;
+import org.apache.arrow.vector.util.ValueVectorUtility;
+import org.hamcrest.collection.IsIterableContainingInOrder;
 import org.junit.ClassRule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
@@ -236,9 +240,11 @@ public void testRunExtendedExpressionsFilter() throws Exception {
       int rowcount = 0;
       while (reader.loadNextBatch()) {
         rowcount += reader.getVectorSchemaRoot().getRowCount();
-        assertTrue(reader.getVectorSchemaRoot().getVector("id").toString().equals("[19, 1, 11]"));
-        assertTrue(reader.getVectorSchemaRoot().getVector("name").toString()
-            .equals("[value_19, value_1, value_11]"));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector("id")),
+            IsIterableContainingInOrder.contains(new Integer[] {19, 1, 11}));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector("name")),
+            IsIterableContainingInOrder.contains(
+                new Text("value_19"), new Text("value_1"), new Text("value_11")));
       }
       assertEquals(3, rowcount);
     }
@@ -331,11 +337,13 @@ public void testRunExtendedExpressionsProjection() throws Exception {
       assertEquals(schema.getFields(), reader.getVectorSchemaRoot().getSchema().getFields());
       int rowcount = 0;
       while (reader.loadNextBatch()) {
-        assertTrue(reader.getVectorSchemaRoot().getVector("add_two_to_column_a").toString()
-            .equals("[21, 3, 13, 23, 47]"));
-        assertTrue(reader.getVectorSchemaRoot().getVector("concat_column_a_and_b").toString()
-            .equals("[value_19 - value_19, value_1 - value_1, value_11 - value_11, " +
-                "value_21 - value_21, value_45 - value_45]"));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector("add_two_to_column_a")),
+            IsIterableContainingInOrder.contains(21, 3, 13, 23, 47));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector("concat_column_a_and_b")),
+            IsIterableContainingInOrder.contains(
+                new Text("value_19 - value_19"), new Text("value_1 - value_1"),
+                new Text("value_11 - value_11"), new Text("value_21 - value_21"),
+                new Text("value_45 - value_45")));
         rowcount += reader.getVectorSchemaRoot().getRowCount();
       }
       assertEquals(5, rowcount);
@@ -370,8 +378,9 @@ public void testRunExtendedExpressionsProjectionWithFilterInsteadOfProjectionExc
       assertEquals(schema.getFields(), reader.getVectorSchemaRoot().getSchema().getFields());
       int rowcount = 0;
       while (reader.loadNextBatch()) {
-        assertTrue(reader.getVectorSchemaRoot().getVector("filter_id_lower_than_20").toString()
-            .equals("[true, true, true, false, false]"));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector(
+            "filter_id_lower_than_20")),
+            IsIterableContainingInOrder.contains(true, true, true, false, false));
         rowcount += reader.getVectorSchemaRoot().getRowCount();
       }
       assertEquals(5, rowcount);
@@ -441,10 +450,12 @@ public void testRunExtendedExpressionsProjectAndFilter() throws Exception {
       assertEquals(schema.getFields(), reader.getVectorSchemaRoot().getSchema().getFields());
       int rowcount = 0;
       while (reader.loadNextBatch()) {
-        assertTrue(reader.getVectorSchemaRoot().getVector("add_two_to_column_a").toString()
-            .equals("[21, 3, 13]"));
-        assertTrue(reader.getVectorSchemaRoot().getVector("concat_column_a_and_b").toString()
-            .equals("[value_19 - value_19, value_1 - value_1, value_11 - value_11]"));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector("add_two_to_column_a")),
+            IsIterableContainingInOrder.contains(21, 3, 13));
+        assertThat(ValueVectorUtility.iterable(reader.getVectorSchemaRoot().getVector("concat_column_a_and_b")),
+            IsIterableContainingInOrder.contains(
+                new Text("value_19 - value_19"), new Text("value_1 - value_1"),
+                new Text("value_11 - value_11")));
         rowcount += reader.getVectorSchemaRoot().getRowCount();
       }
       assertEquals(3, rowcount);

java/vector/src/main/java/org/apache/arrow/vector/util/ValueVectorUtility.java

@@ -19,6 +19,7 @@
 
 import static org.apache.arrow.vector.validate.ValidateUtil.validateOrThrow;
 
+import java.util.Iterator;
 import java.util.function.BiFunction;
 
 import org.apache.arrow.util.Preconditions;
@@ -108,6 +109,34 @@ public static <V extends ValueVector> String getToString(
     return sb.toString();
   }
 
+  /**
+   * Creates an Iterator to iterate over the values in the ValueVector.
+   * @param vector the vector for which to iterate.
+   * @return an Iterator over the values
+   */
+  public static Iterator<Object> iterator(ValueVector vector) {
+    return new Iterator<Object>() {
+      private int index = 0;
+
+      @Override public boolean hasNext() {
+        return index < vector.getValueCount();
+      }
+
+      @Override public Object next() {
+        return vector.getObject(index++);
+      }
+    };
+  }
+
+  /**
+   * Creates an Iterable for the values in a ValueVector.
+   * @param vector the vector to create an iterable for
+   * @return an Iterable for the vector
+   */
+  public static Iterable<Object> iterable(ValueVector vector) {
+    return () -> iterator(vector);
+  }
+
   /**
    * Utility to validate vector in O(1) time.
    */