buckelieg.fn.db.TrySupplier Maven / Gradle / Ivy

/*
 * Copyright 2016- Anatoly Kutyakov
*
* 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 buckelieg.fn.db;

import static java.util.Objects.requireNonNull;

/**
 * Represents a supplier of results.
 * 
 * 
There is no requirement that a new or distinct result be returned each
 * time the supplier is invoked.
 * 

 * This is a functional interface
 * whose functional method is {@link #get()}.
 *
 * @param  the type of results supplied by this supplier
 * @param  a type of an {@link Exception} that might be thrown
 */
@FunctionalInterface
public interface TrySupplier {

    /**
     * Value supplier function which might throw an Exception
     *
     * @return an optional value
     * @throws E an exception if something went wrong
     */
    O get() throws E;

    /**
     * Returns reference of lambda expression.
     *
     * @param trySupplier a function
     * @return lambda as {@link TrySupplier} reference
     * @throws NullPointerException if trySupplier is null
     */
    static  TrySupplier of(TrySupplier trySupplier) {
        return requireNonNull(trySupplier);
    }

}