Java Collection First firstElementOf(final Collection collection)

Description

Returns the first element of the given collection

License

Apache License

Parameter

Parameter	Description
T	a parameter
collection	a parameter

Return

null if the first element is null or the collection is null or empty

Declaration

public static <T> T firstElementOf(final Collection<? extends T> collection) 

Method Source Code

//package com.java2s;
/*/*from  w  w w  .  j ava 2 s  .  com*/
 * Copyright 2002-2008 the original author or authors.
 * 
 * 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.util.Collection;

import java.util.Map;

public class Main {
    /**
     * Returns the first element of the given collection
     * 
     * @param <T>
     * @param collection
     * @return <code>null</code> if the first element is <code>null</code> or
     *         the collection is <code>null</code> or empty
     */
    public static <T> T firstElementOf(final Collection<? extends T> collection) {
        if (isEmpty(collection)) {
            return null;
        }
        return collection.iterator().next();
    }

    /**
     * Return <code>true</code> if the supplied Collection is <code>null</code>
     * or empty. Otherwise, return <code>false</code>.
     * 
     * @param collection the Collection to check
     * @return whether the given Collection is empty
     */
    public static boolean isEmpty(final Collection<?> collection) {
        return collection == null || collection.isEmpty();
    }

    /**
     * Return <code>true</code> if the supplied Map is <code>null</code> or
     * empty. Otherwise, return <code>false</code>.
     * 
     * @param map the Map to check
     * @return whether the given Map is empty
     */
    public static boolean isEmpty(final Map<?, ?> map) {
        return map == null || map.isEmpty();
    }
}

Related

1. first(Collection c)
2. first(Collection collection)
3. first(Collection collection)
4. firstElement(Collection in)
5. firstElement(Collection c)
6. firstElementOf(final Collection items)
7. firstFrom(Collection collection)
8. firstFrom(Collection coll)
9. firstNonEmpty(Collection... collections)