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Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang. The code is tested using the latest revision of the JDK for supported LTS releases: 8, 11, 17 and 21 currently. See https://github.com/apache/commons-lang/blob/master/.github/workflows/maven.yml Please ensure your build environment is up-to-date and kindly report any build issues.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.lang3.function;

import java.util.function.Supplier;

/**
 * Helps use {@link Supplier}.
 *
 * @since 3.13.0
 */
public class Suppliers {

    /**
     * Returns the singleton supplier that always returns null.
     * 
     * This supplier never throws an exception.
     * 
     */
    @SuppressWarnings("rawtypes")
    private static Supplier NUL = () -> null;

    /**
     * Null-safe call to {@link Supplier#get()}.
     *
     * @param  the type of results supplied by this supplier.
     * @param supplier the supplier or null.
     * @return Result of {@link Supplier#get()} or null.
     */
    public static  T get(final Supplier supplier) {
        return supplier == null ? null : supplier.get();
    }

    /**
     * Returns the singleton supplier that always returns null.
     * 
     * This supplier never throws an exception.
     * 
     *
     * @param  Supplied type.
     * @return The NUL singleton.
     * @since 3.14.0
     */
    @SuppressWarnings("unchecked")
    public static  Supplier nul() {
        return NUL;
    }

}