01: /**
02: * ===========================================
03: * JFreeReport : a free Java reporting library
04: * ===========================================
05: *
06: * Project Info: http://reporting.pentaho.org/
07: *
08: * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
09: *
10: * This library is free software; you can redistribute it and/or modify it under the terms
11: * of the GNU Lesser General Public License as published by the Free Software Foundation;
12: * either version 2.1 of the License, or (at your option) any later version.
13: *
14: * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
15: * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
16: * See the GNU Lesser General Public License for more details.
17: *
18: * You should have received a copy of the GNU Lesser General Public License along with this
19: * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20: * Boston, MA 02111-1307, USA.
21: *
22: * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
23: * in the United States and other countries.]
24: *
25: * ------------
26: * IsNullExpression.java
27: * ------------
28: * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
29: */package org.jfree.report.function;
30:
31: /**
32: * Checks, whether a field contains a NULL value.
33: *
34: * @author Thomas Morgner
35: */
36: public class IsNullExpression extends AbstractExpression {
37: /**
38: * The field name.
39: */
40: private String field;
41:
42: /**
43: * Default constructor.
44: */
45: public IsNullExpression() {
46: }
47:
48: /**
49: * Returns the name of the field from where to read the value.
50: *
51: * @return the field.
52: */
53: public String getField() {
54: return field;
55: }
56:
57: /**
58: * Defines the name of the field from where to read the value.
59: *
60: * @param field the field.
61: */
62: public void setField(final String field) {
63: this .field = field;
64: }
65:
66: /**
67: * Return the current expression value. <P> The value depends (obviously) on the expression implementation.
68: *
69: * @return the value of the function.
70: */
71: public Object getValue() {
72: final Object o = getDataRow().get(getField());
73: if (o == null) {
74: return Boolean.TRUE;
75: }
76: return Boolean.FALSE;
77: }
78: }
|