Java Iterable Item concat(Iterable... iterables)

Description

concat

License

Apache License

Declaration

@SafeVarargs
    public static <T> Iterable<T> concat(Iterable<? extends T>... iterables) 

Method Source Code

//package com.java2s;
/*/*from ww  w .  ja va 2 s  . c  o  m*/
 * Copyright 2010 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.*;

public class Main {
    @SafeVarargs
    public static <T> Iterable<T> concat(Iterable<? extends T>... iterables) {
        return concat(Arrays.asList(iterables));
    }

    public static <T> Iterable<T> concat(final List<Iterable<? extends T>> iterables) {
        return new Iterable<T>() {
            @Override
            public Iterator<T> iterator() {
                return new Iterator<T>() {
                    Iterator<? extends T> iter;
                    int pos = 0;

                    @Override
                    public boolean hasNext() {
                        while (pos < iterables.size()) {
                            if (iter == null)
                                iter = iterables.get(pos).iterator();
                            if (iter.hasNext())
                                return true;
                            iter = null;
                            pos++;
                        }
                        return false;
                    }

                    @Override
                    public T next() {
                        while (pos < iterables.size()) {
                            if (iter == null)
                                iter = iterables.get(pos).iterator();
                            if (iter.hasNext())
                                return iter.next();
                            iter = null;
                            pos++;
                        }
                        throw new NoSuchElementException();
                    }

                    @Override
                    public void remove() {
                        throw new UnsupportedOperationException("remove");
                    }
                };
            }
        };
    }
}

Related

1. clear(Iterable iterable)
2. concat(final Iterable> iterables)
3. concat(Iterable first, Iterable second)
4. contains(Iterable iter, Object o)
5. getFirst(final Iterable iterable)
6. getFirst(Iterable iterable)