java/src/com/android/inputmethod/latin/utils/CollectionUtils.java


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/*
 * Copyright (C) 2012 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.
 */

package com.android.inputmethod.latin.utils;

import java.util.ArrayList;
import java.util.Collection;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

public final class CollectionUtils {
    private CollectionUtils() {
        // This utility class is not publicly instantiable.
    }

    @Nonnull
    public static <E> ArrayList<E> arrayAsList(@Nonnull final E[] array, final int start,
            final int end) {
        if (start < 0 || start > end || end > array.length) {
            throw new IllegalArgumentException();
        }

        final ArrayList<E> list = new ArrayList<>(end - start);
        for (int i = start; i < end; i++) {
            list.add(array[i]);
        }
        return list;
    }

    /**
     * Tests whether c contains no elements, true if c is null or c is empty.
     * @param c Collection to test.
     * @return Whether c contains no elements.
     */
    public static boolean isNullOrEmpty(@Nullable final Collection<?> c) {
        return c == null || c.isEmpty();
    }
}