Casts the Iterable to a Collection if it is one. - Java Collection Framework

Java examples for Collection Framework:Iterable

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Description

Casts the Iterable to a Collection if it is one.

Demo Code


//package com.java2s;
import java.util.ArrayList;
import java.util.Collection;

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

public class Main {
    /**//from  w ww.j a  v  a2s  .  co  m
     * Casts the {@link Iterable} to a {@link Collection} if it is one.
     * Otherwise it makes a shallow copy.
     *
     * @param iterable
     * @return the content as a collection.
     */
    public static <T> Collection<T> asCollection(Iterable<T> iterable) {
        return (iterable instanceof Collection) ? (Collection<T>) iterable
                : shallowCopy(iterable);
    }

    /**
     * Generates a new {@link Iterable} that references the items of the given
     * {@link Iterable}.
     *
     * @param <T>
     *          The collection item fieldClass.
     * @param ori
     *          The iterable to get a shallow copy for.
     * @return The shallow copy.
     */
    public static <T> List<T> shallowCopy(Iterable<T> ori) {
        ArrayList<T> copy = new ArrayList<T>();

        for (T t : ori) {
            copy.add(t);
        }

        return copy;
    }

    /**
     * Generates a collection that references the items of the given
     * {@link Iterator}.<br>
     * The iterator should be at its start position.
     *
     * @param <T>
     *          The collection item fieldClass.
     * @param iter
     *          The iterator to get a shallow copy for.
     * @return The shallow copy.
     */
    public static <T> List<T> shallowCopy(Iterator<T> iter) {
        ArrayList<T> copy = new ArrayList<T>();

        while (iter.hasNext()) {
            copy.add(iter.next());
        }

        return copy;
    }
}

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