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/*
* Copyright (C) 2007 The Guava 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.
*/
package org.glassfish.jersey.internal.guava;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.Predicate;
import static org.glassfish.jersey.internal.guava.Preconditions.checkNotNull;
/**
* This class contains static utility methods that operate on or return objects
* of type {@code Iterable}. Except as noted, each method has a corresponding
* {@link Iterator}-based method in the {@link Iterators} class.
*
*
Performance notes: Unless otherwise noted, all of the iterables
* produced in this class are lazy, which means that their iterators
* only advance the backing iteration when absolutely necessary.
*
*
See the Guava User Guide article on
* {@code Iterables}.
*
* @author Kevin Bourrillion
* @author Jared Levy
* @since 2.0 (imported from Google Collections Library)
*/
final class Iterables {
private Iterables() {
}
/**
* Returns the first element in {@code iterable} or {@code defaultValue} if
* the iterable is empty. The {@link Iterators} analog to this method is
* {@link Iterators#getNext}.
*
*
If no default value is desired (and the caller instead wants a
* {@link NoSuchElementException} to be thrown), it is recommended that
* {@code iterable.iterator().next()} is used instead.
*
* @param defaultValue the default value to return if the iterable is empty
* @return the first element of {@code iterable} or the default value
* @since 7.0
*/
public static T getFirst(Iterable iterable, T defaultValue) {
return Iterators.getNext(iterable.iterator(), defaultValue);
}
}