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Add ArrayUtils.getDimensions(Object)
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‎src/changes/changes.xml‎

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@@ -114,6 +114,7 @@ The <action> type attribute can be add,update,fix,remove.
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<action type="add" dev="ggregory" due-to="Gary Gregory">JavaVersion.get(String) now support Java 26 and 27.</action>
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<action issue="LANG-1810" type="add" dev="ggregory" due-to="Yelim Koo, Gary Gregory">Deprecate ArrayUtils.SOFT_MAX_ARRAY_LENGTH in favor of SAFE_MAX_ARRAY_LENGTH #1559.</action>
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<action type="add" dev="ggregory" due-to="Gary Gregory, Theodora Anastasia Lazaridou">Add long support to BitField #1561.</action>
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<action type="add" dev="ggregory" due-to="Gary Gregory">Add ArrayUtils.getDimensions(Object).</action>
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<!-- UPDATE -->
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<action type="update" dev="ggregory" due-to="Gary Gregory, Dependabot">Bump org.apache.commons:commons-parent from 92 to 96 #1498.</action>
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<action type="update" dev="ggregory" due-to="Gary Gregory">[test] Bump org.apache.commons:commons-text from 1.14.0 to 1.15.0.</action>

‎src/main/java/org/apache/commons/lang3/ArrayUtils.java‎

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@@ -1849,6 +1849,29 @@ public static <T> Class<T> getComponentType(final T[] array) {
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return ClassUtils.getComponentType(ObjectUtils.getClass(array));
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}
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/**
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* Gets the number of dimensions of an array.
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* <p>
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* The <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.3">JVM specification</a> limits the number of dimensions to 255.
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* </p>
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*
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* @param array the array, may be {@code null}.
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* @return The number of dimensions, 0 if the input is null or not an array. The JVM specification limits the number of dimensions to 255.
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* @since 3.21.0
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* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.3">JVM specification Field Descriptors</a>
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*/
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public static int getDimensions(final Object array) {
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int dimensions = 0;
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if (array != null) {
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Class<?> arrayClass = array.getClass();
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while (arrayClass.isArray()) {
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dimensions++;
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arrayClass = arrayClass.getComponentType();
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}
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}
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return dimensions;
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}
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/**
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* Gets the length of the specified array.
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* This method can deal with {@link Object} arrays and with primitive arrays.

‎src/test/java/org/apache/commons/lang3/ArrayUtilsGetDimensions.java‎

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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import java.util.stream.Stream;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.Arguments;
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import org.junit.jupiter.params.provider.MethodSource;
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class ArrayUtilsGetDimensions {
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// Tests cyclic references
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static class Node {
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String name;
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Node next;
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Node(final String name) {
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this.name = name;
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}
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}
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private static Stream<Arguments> provideArraysWithExpectedDimensions() {
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return Stream.of(Arguments.of(new int[] { 1, 2, 3 }, 1), Arguments.of(new int[][] { { 1, 2 }, { 3, 4 } }, 2),
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Arguments.of(new int[][][] { { { 1 } } }, 3), Arguments.of(new String[] { "a", "b" }, 1), Arguments.of(new String[][] { { "a" }, { "b" } }, 2),
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Arguments.of(new Object[5], 1), Arguments.of(new boolean[2][3], 2), Arguments.of(new char[1][2][3][4], 4));
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}
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@Test
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void testArraysOfArrays() {
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final Object[] arrayOfArrays = { new int[] { 1, 2 }, new String[] { "a", "b" } };
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assertEquals(1, ArrayUtils.getDimensions(arrayOfArrays));
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}
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@Test
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void testArraysWithCyclicObjects() {
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final Node node1 = new Node("A");
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final Node node2 = new Node("B");
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node1.next = node2;
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node2.next = node1; // Create cycle
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final Node[] arr = { node1, node2 };
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assertEquals(1, ArrayUtils.getDimensions(arr));
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final Node[][] arr2D = { { node1, node2 }, { node2, node1 } };
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assertEquals(2, ArrayUtils.getDimensions(arr2D));
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}
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@Test
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void testArraysWithNullElements() {
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final String[] arrWithNull = { null, "test", null };
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assertEquals(1, ArrayUtils.getDimensions(arrWithNull));
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final String[][] arr2DWithNull = { { null, "a" }, null, { "b" } };
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assertEquals(2, ArrayUtils.getDimensions(arr2DWithNull));
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}
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@Test
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void testEmptyOneDimensionalArrays() {
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assertEquals(1, ArrayUtils.getDimensions(new int[0]));
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assertEquals(1, ArrayUtils.getDimensions(new String[0]));
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}
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@Test
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void testHighDimensionalArrays() {
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assertEquals(4, ArrayUtils.getDimensions(new int[1][2][3][4]));
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assertEquals(5, ArrayUtils.getDimensions(new byte[1][1][1][1][1]));
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assertEquals(6, ArrayUtils.getDimensions(new String[2][2][2][2][2][2]));
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}
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@Test
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void testInitializedArrays() {
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final int[] arr1D = { 1, 2, 3, 4, 5 };
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assertEquals(1, ArrayUtils.getDimensions(arr1D));
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final int[][] arr2D = { { 1, 2, 3 }, { 4, 5, 6 } };
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assertEquals(2, ArrayUtils.getDimensions(arr2D));
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final int[][][] arr3D = { { { 1, 2 }, { 3, 4 } }, { { 5, 6 }, { 7, 8 } } };
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assertEquals(3, ArrayUtils.getDimensions(arr3D));
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}
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@Test
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void testJaggedArrays() {
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final int[][] jagged = { { 1, 2 }, { 3, 4, 5 }, { 6 } };
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assertEquals(2, ArrayUtils.getDimensions(jagged));
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final String[][] jaggedStrings = { { "a" }, { "b", "c", "d" } };
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assertEquals(2, ArrayUtils.getDimensions(jaggedStrings));
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}
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@Test
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void testNonArrayObject() {
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assertEquals(0, ArrayUtils.getDimensions("Not an array"));
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assertEquals(0, ArrayUtils.getDimensions(42));
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assertEquals(0, ArrayUtils.getDimensions(new Object()));
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assertEquals(0, ArrayUtils.getDimensions(3.14));
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}
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@Test
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void testNullArray() {
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assertEquals(0, ArrayUtils.getDimensions(null));
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}
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@Test
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void testOneDimensionalObjectArrays() {
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assertEquals(1, ArrayUtils.getDimensions(new String[5]));
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assertEquals(1, ArrayUtils.getDimensions(new Object[10]));
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assertEquals(1, ArrayUtils.getDimensions(new Integer[3]));
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}
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@Test
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void testOneDimensionalPrimitiveArrays() {
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assertEquals(1, ArrayUtils.getDimensions(new int[5]));
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assertEquals(1, ArrayUtils.getDimensions(new byte[10]));
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assertEquals(1, ArrayUtils.getDimensions(new short[3]));
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assertEquals(1, ArrayUtils.getDimensions(new long[7]));
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assertEquals(1, ArrayUtils.getDimensions(new float[4]));
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assertEquals(1, ArrayUtils.getDimensions(new double[6]));
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assertEquals(1, ArrayUtils.getDimensions(new boolean[2]));
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assertEquals(1, ArrayUtils.getDimensions(new char[8]));
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}
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@Test
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void testThreeDimensionalArrays() {
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assertEquals(3, ArrayUtils.getDimensions(new int[2][3][4]));
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assertEquals(3, ArrayUtils.getDimensions(new String[1][2][3]));
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assertEquals(3, ArrayUtils.getDimensions(new Object[5][5][5]));
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}
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@Test
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void testTwoDimensionalArrays() {
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assertEquals(2, ArrayUtils.getDimensions(new int[3][4]));
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assertEquals(2, ArrayUtils.getDimensions(new String[2][5]));
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assertEquals(2, ArrayUtils.getDimensions(new double[1][1]));
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}
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@ParameterizedTest
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@MethodSource("provideArraysWithExpectedDimensions")
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void testVariousArrayTypes(final Object array, final int expectedDimensions) {
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assertEquals(expectedDimensions, ArrayUtils.getDimensions(array));
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}
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}

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