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: * IsEmptyExpression.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 is empty. A field is considered empty, if it contains the value 'null',
33: * or an string that is empty or only consists of whitespaces or a number that evaluates to zero.
34: *
35: * @author Thomas Morgner
36: */
37: public class IsEmptyExpression extends AbstractExpression {
38: /**
39: * The field name.
40: */
41: private String field;
42:
43: /**
44: * Default constructor.
45: */
46: public IsEmptyExpression() {
47: }
48:
49: /**
50: * Returns the name of the field from where to read the value.
51: *
52: * @return the field.
53: */
54: public String getField() {
55: return field;
56: }
57:
58: /**
59: * Defines the name of the field from where to read the value.
60: *
61: * @param field the field.
62: */
63: public void setField(final String field) {
64: this .field = field;
65: }
66:
67: /**
68: * Return the current expression value. <P> The value depends (obviously) on
69: * the expression implementation.
70: *
71: * @return the value of the function.
72: */
73: public Object getValue() {
74: final Object o = getDataRow().get(getField());
75: if (o == null) {
76: return Boolean.TRUE;
77: }
78: if (o instanceof String) {
79: final String s = (String) o;
80: if (s.trim().length() == 0) {
81: return Boolean.TRUE;
82: }
83: return Boolean.FALSE;
84: }
85: if (o instanceof Number) {
86: final Number n = (Number) o;
87: if (n.doubleValue() == 0) {
88: return Boolean.TRUE;
89: }
90: return Boolean.FALSE;
91: }
92: return Boolean.FALSE;
93: }
94: }
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