Android Array Create emptyArray(Class kind)

Description

Returns an empty array of the specified type.

License

Apache License

Declaration

public static <T> T[] emptyArray(Class<T> kind) 

Method Source Code

//package com.java2s;
/*//  ww  w .  ja v  a 2  s .c o  m
 * Copyright (C) 2006 The Android Open Source Project
 *
 * 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.lang.reflect.Array;

public class Main {
    private static Object[] EMPTY = new Object[0];
    private static final int CACHE_SIZE = 73;
    private static Object[] sCache = new Object[CACHE_SIZE];

    /**
     * Returns an empty array of the specified type.  The intent is that
     * it will return the same empty array every time to avoid reallocation,
     * although this is not guaranteed.
     */
    public static <T> T[] emptyArray(Class<T> kind) {
        if (kind == Object.class) {
            return (T[]) EMPTY;
        }

        int bucket = ((System.identityHashCode(kind) / 8) & 0x7FFFFFFF)
                % CACHE_SIZE;
        Object cache = sCache[bucket];

        if (cache == null || cache.getClass().getComponentType() != kind) {
            cache = Array.newInstance(kind, 0);
            sCache[bucket] = cache;

            // Log.e("cache", "new empty " + kind.getName() + " at " + bucket);
        }

        return (T[]) cache;
    }
}

Related

1. emptyArray(Class kind)
2. emptyArray(Class kind)
3. nullToEmpty(Boolean[] array)
4. nullToEmpty(Byte[] array)