Java Collection Search indexOf(final Collection c, final Object elem)

Description

Get the index position of an element in a collection

License

Open Source License

Parameter

Parameter	Description
c	The Collection.
elem	the element to find the index of

Return

the element index

Declaration

public static int indexOf(final Collection c, final Object elem) 

Method Source Code

//package com.java2s;
/* $Id$/*w  w  w .j  a v  a 2s.  co m*/
 *******************************************************************************
 * Copyright (c) 2009 Contributors - see below
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Bob Tarling
 *******************************************************************************
 */

import java.util.Collection;
import java.util.List;

public class Main {
    /**
     * Get the index position of an element in a collection
     *
     * @param c The Collection.
     * @param elem the element to find the index of
     * @return the element index
     */
    public static int indexOf(final Collection c, final Object elem) {
        if (c instanceof List) {
            return ((List) c).indexOf(elem);
        } else {
            int index = 0;
            for (Object element : c) {
                if (element == elem) {
                    return index;
                } else {
                    ++index;
                }
            }
            return -1;
        }
    }
}

Related

1. hasOneItem(final Collection col)
2. hasOtherThan(Collection a, Collection b)
3. hasValidElement(Collection collection)
4. hasValue(Collection collection)
5. indexOf(Collection stringCollection, String str)
6. indexOfInstance(final Collection collection, final T instance)
7. indexOfObjectIdentity(Collection collection, Object object)