Here you can find the source of indexOf(final T[] array, final T value)
public static <T> int indexOf(final T[] array, final T value)
//package com.java2s; /*/*from w ww . jav a 2 s .c o m*/ * @(#)$Id: ArrayUtils.java 3619 2008-03-26 07:23:03Z yui $ * * Copyright 2006-2008 Makoto YUI * * 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. * * Contributors: * Makoto YUI - ported from jakarta commons lang */ 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; public static <T> int indexOf(final T[] array, final T value) { final int alen = array.length; for (int i = 0; i < alen; i++) { if (value.equals(array[i])) { return i; } } return INDEX_NOT_FOUND; } public static <T> int indexOf(final T[] array, final T value, final int startIndex) { final int alen = array.length; for (int i = startIndex; i < alen; i++) { if (value.equals(array[i])) { return i; } } return INDEX_NOT_FOUND; } public static int indexOf(final int[] array, final int value) { final int alen = array.length; for (int i = 0; i < alen; i++) { if (value == array[i]) { return i; } } return INDEX_NOT_FOUND; } public static int indexOf(final int[] array, final int valueToFind, int startIndex, int endIndex) { if (array == null) { return INDEX_NOT_FOUND; } final int til = Math.min(endIndex, array.length); if (startIndex < 0 || startIndex > til) { throw new IllegalArgumentException("Illegal startIndex: " + startIndex); } for (int i = startIndex; i < til; i++) { if (valueToFind == array[i]) { return i; } } return INDEX_NOT_FOUND; } public static int indexOf(final byte[] array, final byte 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; } public static boolean equals(final char[] a, final char[] a2, final int off, final int len) { if (a == a2) { return true; } if (a == null || a2 == null) { return false; } int length = a.length; if (len != length) { return false; } for (int i = 0; i < len; i++) { if (a[i] != a2[off + i]) { return false; } } return true; } }