001: /*
002: * $Id: BaseNumberDataType.java,v 1.9 2005/05/02 22:29:40 ahimanikya Exp $
003: * =======================================================================
004: * Copyright (c) 2002-2005 Axion Development Team. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above
011: * copyright notice, this list of conditions and the following
012: * disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The names "Tigris", "Axion", nor the names of its contributors may
020: * not be used to endorse or promote products derived from this
021: * software without specific prior written permission.
022: *
023: * 4. Products derived from this software may not be called "Axion", nor
024: * may "Tigris" or "Axion" appear in their names without specific prior
025: * written permission.
026: *
027: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
028: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
029: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
030: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
031: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
032: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
033: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
034: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
035: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
036: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
037: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
038: * =======================================================================
039: */
040:
041: package org.axiondb.types;
042:
043: import org.axiondb.AxionException;
044:
045: /**
046: * An abstract base {@link org.axiondb.DataType}for {@link Number}types.
047: *
048: * @version $Revision: 1.9 $ $Date: 2005/05/02 22:29:40 $
049: * @author Rodney Waldhoff
050: */
051: public abstract class BaseNumberDataType extends BaseDataType {
052:
053: public BaseNumberDataType() {
054: }
055:
056: /**
057: * Returns <code>true</code> iff <i>value </i> is <code>String</code> that can be
058: * {@link #convert converted}without exception, <code>null</code>, or a
059: * {@link Number Number}.
060: */
061: public boolean accepts(Object value) {
062: if (value instanceof Number) {
063: return true;
064: } else if (null == value) {
065: return true;
066: } else if (value instanceof String) {
067: return true;
068: } else {
069: return false;
070: }
071: }
072:
073: /**
074: * Returns <i>value </i> if <i>value </i> is <code>null</code> and throws
075: * {@link IllegalArgumentException}otherwise. Subclasses should override this method
076: * and call <code>super.convert(value)</code> as their last case.
077: *
078: * @throws AxionException
079: */
080: public Object convert(Object value) throws AxionException {
081: if (null == value) {
082: return null;
083: }
084: throw new AxionException(cantConvertMessage(value));
085: }
086:
087: /** This base implementation returns <code>true</code>. */
088: public boolean supportsSuccessor() {
089: return true;
090: }
091:
092: protected Number toNumber(Object value) throws AxionException {
093: return (Number) (convert(value));
094: }
095:
096: private String cantConvertMessage(Object value) {
097: return "Can't convert " + value.getClass().getName() + " "
098: + value + " to " + toString() + ".";
099: }
100:
101: private static final long serialVersionUID = 3150249045649554897L;
102: }
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