org.jdesktop.swingx.util.Contract Maven / Gradle / Ivy
/*
* $Id: Contract.java 3100 2008-10-14 22:33:10Z rah003 $
*
* 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 (int i = 0; i < array.length; i++) {
asNotNull(array[i], message);
}
}
}
return input;
}
}