Mega Code Archive
Get the index and last index of an int type value array
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/* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.lang.reflect.Array;
/**
* <p>Operations on arrays, primitive arrays (like <code>int[]</code>) and
* primitive wrapper arrays (like <code>Integer[]</code>).</p>
*
* <p>This class tries to handle <code>null</code> input gracefully.
* An exception will not be thrown for a <code>null</code>
* array input. However, an Object array that contains a <code>null</code>
* element may throw an exception. Each method documents its behaviour.</p>
*
* @author Stephen Colebourne
* @author Moritz Petersen
* @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
* @author Nikolay Metchev
* @author Matthew Hawthorne
* @author Tim O'Brien
* @author Pete Gieser
* @author Gary Gregory
* @author <a href="mailto:equinus100@hotmail.com">Ashwin S</a>
* @author Maarten Coene
* @since 2.0
* @version $Id: ArrayUtils.java 632503 2008-03-01 00:21:52Z ggregory $
*/
public class Main {
/**
* The index value when an element is not found in a list or array: <code>-1</code>.
* This value is returned by methods in this class and can also be used in comparisons with values returned by
* various method from {@link java.util.List}.
*/
public static final int INDEX_NOT_FOUND = -1;
// int IndexOf
//-----------------------------------------------------------------------
/**
* <p>Finds the index of the given value in the array.</p>
*
* <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
*
* @param array the array to search through for the object, may be <code>null</code>
* @param valueToFind the value to find
* @return the index of the value within the array,
* {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
*/
public static int indexOf(int[] array, int valueToFind) {
return indexOf(array, valueToFind, 0);
}
/**
* <p>Finds the index of the given value in the array starting at the given index.</p>
*
* <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
*
* <p>A negative startIndex is treated as zero. A startIndex larger than the array
* length will return {@link #INDEX_NOT_FOUND} (<code>-1</code>).</p>
*
* @param array the array to search through for the object, may be <code>null</code>
* @param valueToFind the value to find
* @param startIndex the index to start searching at
* @return the index of the value within the array,
* {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
*/
public static int indexOf(int[] array, int valueToFind, int startIndex) {
if (array == null) {
return INDEX_NOT_FOUND;
}
if (startIndex < 0) {
startIndex = 0;
}
for (int i = startIndex; i < array.length; i++) {
if (valueToFind == array[i]) {
return i;
}
}
return INDEX_NOT_FOUND;
}
/**
* <p>Finds the last index of the given value within the array.</p>
*
* <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
*
* @param array the array to travers backwords looking for the object, may be <code>null</code>
* @param valueToFind the object to find
* @return the last index of the value within the array,
* {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
*/
public static int lastIndexOf(int[] array, int valueToFind) {
return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
}
/**
* <p>Finds the last index of the given value in the array starting at the given index.</p>
*
* <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
*
* <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} (<code>-1</code>). A startIndex larger than the
* array length will search from the end of the array.</p>
*
* @param array the array to traverse for looking for the object, may be <code>null</code>
* @param valueToFind the value to find
* @param startIndex the start index to travers backwards from
* @return the last index of the value within the array,
* {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
*/
public static int lastIndexOf(int[] array, int valueToFind, int startIndex) {
if (array == null) {
return INDEX_NOT_FOUND;
}
if (startIndex < 0) {
return INDEX_NOT_FOUND;
} else if (startIndex >= array.length) {
startIndex = array.length - 1;
}
for (int i = startIndex; i >= 0; i--) {
if (valueToFind == array[i]) {
return i;
}
}
return INDEX_NOT_FOUND;
}
/**
* <p>Checks if the value is in the given array.</p>
*
* <p>The method returns <code>false</code> if a <code>null</code> array is passed in.</p>
*
* @param array the array to search through
* @param valueToFind the value to find
* @return <code>true</code> if the array contains the object
*/
public static boolean contains(int[] array, int valueToFind) {
return indexOf(array, valueToFind) != INDEX_NOT_FOUND;
}
}
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