Java Collection to Array toArray(Collection c, T[] sample)

Description

This is a replacement for Collection#toArray(Object[]) .

License

Apache License

Declaration

public static <T> T[] toArray(Collection<T> c, T[] sample) 

Method Source Code

//package com.java2s;
/*/*from w ww.j  a  va 2  s .com*/
 * Copyright 2000-2014 JetBrains s.r.o.
 *
 * 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.Collection;

public class Main {
    private static final int ARRAY_COPY_THRESHOLD = 20;

    /**
     * This is a replacement for {@link Collection#toArray(Object[])}. For small collections it is faster to stay at java level and refrain
     * from calling JNI {@link System#arraycopy(Object, int, Object, int, int)}
     */

    public static <T> T[] toArray(Collection<T> c, T[] sample) {
        final int size = c.size();
        if (size == sample.length && size < ARRAY_COPY_THRESHOLD) {
            int i = 0;
            for (T t : c) {
                sample[i++] = t;
            }
            return sample;
        }

        return c.toArray(sample);
    }
}

Related

1. toArray(Collection collection)
2. toArray(Collection list)
3. toArray(Collection stringCollection)
4. toArray(Collection strings)
5. toArray(Collection values)
6. toArray(Collection collection)
7. toArray(Collection list, Object[] type)
8. toArray(final Collection c)
9. toArray(final Collection coll, byte[] array)