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objectify-led is a small Java library for binding object or class properties at runtime using annotations, reducing boilerplate code. Values can be taken from the System, from properties files, any arbitrary source in fact, and automatically set on properties.

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/*
 * Copyright 2009-2010 Steve Chaloner
 *
 * 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 be.objectify.led.util;

import java.util.Collection;

/**
 * Utility methods for asserting contracts.
 *
 * @author Steve Chaloner
 */
public final class ContractUtils
{
    private ContractUtils()
    {
    }

    /**
     * Checks if object is null.  An IllegalArgumentException is thrown
     * if it is null.
     *
     * @param object the object
     * @param objectName   the name to reference the object by for exception messages
     */
    public static void notNull(Object object,
                               String objectName)
    {
        if (objectName == null)
        {
            throw new IllegalArgumentException("objectName must not be null");
        }
        if (object == null)
        {
            throw new IllegalArgumentException(objectName + " must not be null");
        }
    }

    /**
     * Checks if objects is null, and if any of its contents are null.  An
     * IllegalArgumentException is thrown if either of these cases are true.
     *
     * @param objects the array of objects
     * @param objectName  the name to reference the array by for exception messages
     */
    public static void nonNull(Object[] objects,
                               String objectName)
    {
        notNull(objects,
                     objectName);

        for (Object object : objects)
        {
            if (object == null)
            {
                throw new IllegalArgumentException("All items of " + objectName + " must be non-null");
            }
        }
    }

    /**
     * Checks if objects is null, and if any of its contents are null.  An
     * IllegalArgumentException is thrown if either of these cases are true.
     *
     * @param objects the collection of objects
     * @param objectName    the name to reference the collection by for exception messages
     */
    public static void nonNull(Collection objects,
                               String objectName)
    {
        notNull(objects,
                     objectName);

        for (Object object : objects)
        {
            if (object == null)
            {
                throw new IllegalArgumentException("All items of " + objectName + " must be non-null");
            }
        }
    }
}