Java Iterable to List iterableAsList(Iterable iterable)

Description

Creates a new List from a given Iterable

License

Apache License

Parameter

Parameter	Description
iterable	a parameter

Declaration

public static <E> List<E> iterableAsList(Iterable<E> iterable) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright 2011 Danny Kunz/* www .java 2s. c  o  m*/
 * 
 * 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.ArrayList;

import java.util.Iterator;
import java.util.List;

public class Main {
    /**
     * Creates a new {@link List} from a given {@link Iterable}
     * 
     * @param iterable
     * @return
     */
    public static <E> List<E> iterableAsList(Iterable<E> iterable) {
        return iterable == null ? new ArrayList<E>() : iteratorAsList(iterable.iterator());
    }

    /**
     * Creates a new {@link List} from a given {@link Iterator}
     * 
     * @param iterator
     * @return
     */
    public static <E> List<E> iteratorAsList(Iterator<E> iterator) {
        //    
        List<E> retlist = new ArrayList<E>();

        //
        if (iterator != null) {
            while (iterator.hasNext()) {
                retlist.add(iterator.next());
            }
        }

        //
        return retlist;
    }

    /**
     * Returns the given {@link List} instance or a new {@link List} instance if the given one is null. The returned instance will
     * contain all elements of the given {@link List} and additionally the further given element. <br>
     * <br>
     * This function will return always an instance, even if the given list is null.
     * 
     * @param list
     * @param element
     * @return given {@link List} instance or new {@link List} instance if given {@link List} instance is null
     */
    public static <E> List<E> add(List<? extends E> list, E element) {
        //
        @SuppressWarnings("unchecked")
        List<E> retlist = (List<E>) list;

        //
        if (list == null) {
            retlist = new ArrayList<E>();
        }

        //
        retlist.add(element);

        //
        return retlist;
    }

    /**
     * Similar to {@link #add(List, Object)} allowing to specify an index position
     * 
     * @param list
     * @param index
     * @param element
     * @return the given {@link List} instance or a new one
     */
    public static <E> List<E> add(List<? extends E> list, int index, E element) {
        //
        @SuppressWarnings("unchecked")
        List<E> retlist = (List<E>) list;

        //
        if (list == null) {
            retlist = new ArrayList<E>();
        }

        //
        while (list.size() < index) {
            list.add(null);
        }

        //
        retlist.add(index, element);

        //
        return retlist;
    }

    /**
     * Returns the given {@link List} instance or a new {@link List} instance if the given one is null. The returned instance will
     * contain all elements of the given {@link List} and additionally all further given elements. <br>
     * <br>
     * This function will return always a instance, even if the given list is null.
     * 
     * @param list
     * @param elements
     * @return given {@link List} instance or new {@link List} instance if given {@link List} instance is null
     */
    public static <E> List<E> add(List<? extends E> list, E... elements) {
        //
        @SuppressWarnings("unchecked")
        List<E> retlist = (List<E>) list;

        //
        if (list == null) {
            retlist = new ArrayList<E>();
        }

        //
        if (elements != null) {
            for (E element : elements) {
                retlist.add(element);
            }
        }

        //
        return retlist;
    }

    /**
     * Similar to {@link #add(List, Object...)} allowing to specify an index position
     * 
     * @param list
     * @param index
     * @param elements
     * @return the given {@link List} instance or a new one
     */
    public static <E> List<E> add(List<? extends E> list, int index, E... elements) {
        //
        @SuppressWarnings("unchecked")
        List<E> retlist = (List<E>) list;

        //
        if (list == null) {
            retlist = new ArrayList<E>();
        }

        //
        while (list.size() < index) {
            list.add(null);
        }

        //
        int relative = 0;
        if (elements != null) {
            for (E element : elements) {
                retlist.add(index + relative, element);
                relative++;
            }
        }

        //
        return retlist;
    }
}

Related

1. iterable2List(Iterable iterable)
2. iterableToCollection(Iterable c, Collection list)
3. iterableToCollection(Iterable c, Collection list)
4. iterableToList(Iterable iterable)
5. iterableToList(Iterable input)