UnmodifiableCollections.java

/*
 * Configurate
 * Copyright (C) zml and Configurate contributors
 *
 * 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 org.spongepowered.configurate.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Provides a set of methods that produce unmodifiable copies of collections.
 */
public class UnmodifiableCollections {
    /**
     * Creates an unmodifiable copy of the given {@link List} instance.
     * 
     * @param original the list to be copied
     * @param <E> the type of every item in the entry
     * @return a unmodifiable copy of the given {@link List} instance
     */
    public static <E> List<E> copyOf(List<E> original) {
        switch (original.size()) {
            case 0:
                return Collections.emptyList();
            case 1:
                return Collections.singletonList(original.get(0));
            default:
                return Collections.unmodifiableList(new ArrayList<>(original));
        }
    }
}