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A convenient way to organize asynchronous code. Promises are a faster and more efficient version of JavaScript's Promise and Java's CompletionStage's.

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/*
 * Copyright (C) 2020 ActiveJ LLC.
 *
 * 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 io.activej.promise;

import org.jetbrains.annotations.Nullable;

/**
 * Represents a {@link CompletePromise} with result that equals {@code null}.
 * Optimized for multiple reuse since its result never changes.
 */
public final class CompleteNullPromise extends CompletePromise {
	static final CompleteNullPromise INSTANCE = new CompleteNullPromise<>();

	@SuppressWarnings("unchecked")
	static  CompleteNullPromise instance() {
		return (CompleteNullPromise) INSTANCE;
	}

	private CompleteNullPromise() {}

	@Nullable
	@Override
	public final T getResult() {
		return null;
	}
}