Java List First Item getFirst(List l)

Description

Return the first item of l if it isn't empty, otherwise null.

License

Open Source License

Parameter

Parameter	Description
T	type of list.
l	the list.

Return

the first item of l or null.

Declaration

public static <T> T getFirst(List<T> l) 

Method Source Code

//package com.java2s;
/*/* ww  w . j a  va2 s . co  m*/
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 2008 jOpenDocument, by ILM Informatique. All rights reserved.
 * 
 * The contents of this file are subject to the terms of the GNU
 * General Public License Version 3 only ("GPL").  
 * You may not use this file except in compliance with the License. 
 * You can obtain a copy of the License at http://www.gnu.org/licenses/gpl-3.0.html
 * See the License for the specific language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each file.
 * 
 */

import java.util.Collection;

import java.util.List;

public class Main {
    public static <T> T getFirst(Collection<T> l) {
        return l.size() > 0 ? l.iterator().next() : null;
    }

    /**
     * Return the first item of <code>l</code> if it isn't empty, otherwise <code>null</code>.
     * 
     * @param <T> type of list.
     * @param l the list.
     * @return the first item of <code>l</code> or <code>null</code>.
     */
    public static <T> T getFirst(List<T> l) {
        return getNoExn(l, 0);
    }

    /**
     * Return the item no <code>index</code> of <code>l</code> if it exists, otherwise
     * <code>null</code>.
     * 
     * @param <T> type of list.
     * @param l the list.
     * @param index the wanted index.
     * @return the corresponding item of <code>l</code> or <code>null</code>.
     */
    public static <T> T getNoExn(List<T> l, int index) {
        return index >= 0 && index < l.size() ? l.get(index) : null;
    }
}

Related

1. formatEJBQLObjectRangeRestriction(final String fieldName, final Object value1, final Object value2, final String paramName1, final String paramName2, List paramsName, List