org.jdesktop.swingx.util.Contract Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of swingx-all Show documentation

Fork of the inactive swingx-all library

There is a newer version: 1.7.2

/*
 * $Id: Contract.java 4028 2011-06-03 19:32:19Z kschaefe $
 *
 * Copyright 2006 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.jdesktop.swingx.util;

/**
 * Utility class for checking contracts.
 *
 * @author Jeanette Winzenburg
 */
public class Contract {

    private Contract() {

    }

    /**
     * Tests the input parameter against null. If the input is
     * an array, checks all of its elements as well. Returns the
     * unchanged parameter if not null, throws a NullPointerException
     * otherwise. 
     * 

     * PENDING: type of exception? there are raging debates, some
     * favour an IllegalArgument? 

     * 
     * PENDING: the implementation uses a unchecked type cast to an array.
     * can we do better, how?
     *
     * @param      the type of the input parameter
     * @param input   the argument to check against null.
     * @param message the text of the exception if the argument is null
     * @return the input if not null
     * @throws NullPointerException if input is null
     */
    @SuppressWarnings("unchecked")
    public static  T asNotNull(T input, String message) {
        if (input == null)
            throw new NullPointerException(message);

        if (input.getClass().isArray()) {
            if (!input.getClass().getComponentType().isPrimitive()) {
                T[] array = (T[]) input;
                for (T elem : array) {
                    asNotNull(elem, message);
                }
            }
        }

        return input;
    }
}