Exposes iterator as an Iterable . - Java Collection Framework

Java examples for Collection Framework:Iterator

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Description

Exposes iterator as an Iterable .

Demo Code

/**//  w w  w  . ja va2 s  .  c  o  m
 * Copyright (c) 2002-2013 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
import java.io.File;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

public class Main{
    /**
     * Exposes {@code iterator} as an {@link Iterable}. It breaks the contract
     * of {@link Iterable} in that it returns the supplied iterator instance for
     * each call to {@code iterator()} on the returned {@link Iterable}
     * instance. This method mostly exists to make it easy to use an
     * {@link Iterator} in a for-loop.
     * 
     * @param <T> the type of items in the iterator.
     * @param iterator the iterator to expose as an {@link Iterable}.
     * @return the supplied iterator posing as an {@link Iterable}.
     */
    public static <T> Iterable<T> asIterable(final Iterator<T> iterator) {
        return new Iterable<T>() {
            public Iterator<T> iterator() {
                return iterator;
            }
        };
    }
    /**
     * Creates an {@link Iterable} for iterating over the lines of a text file.
     * @param file the file to get the lines for.
     * @return an {@link Iterable} for iterating over the lines of a text file.
     */
    public static ClosableIterable<String> asIterable(final File file) {
        return new ClosableIterable<String>() {
            private ClosableIterator<String> mostRecentIterator;

            @Override
            public Iterator<String> iterator() {
                try {
                    if (mostRecentIterator != null)
                        mostRecentIterator.close();
                    mostRecentIterator = asIterator(file);
                    return mostRecentIterator;
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }

            @Override
            public void close() {
                if (mostRecentIterator != null)
                    mostRecentIterator.close();
            }
        };
    }
    /**
     * Creates an {@link Iterator} for iterating over the lines of a text file.
     * The opened file is closed if an exception occurs during reading or when
     * the files has been read through all the way.
     * @param file the file to get the lines for.
     * @return an {@link Iterator} for iterating over the lines of a text file.
     */
    public static ClosableIterator<String> asIterator(File file)
            throws IOException {
        return new LinesOfFileIterator(file);
    }
}

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