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: * IsEmptyDataExpression.java
27: * ------------
28: * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
29: */package org.jfree.report.function.bool;
30:
31: import javax.swing.table.TableModel;
32:
33: import org.jfree.report.function.AbstractExpression;
34: import org.jfree.report.function.ExpressionRuntime;
35:
36: /**
37: * An expression that checks, whether the current report has a non-empty datasource.
38: *
39: * @author Thomas Morgner
40: */
41: public class IsEmptyDataExpression extends AbstractExpression {
42: /**
43: * Default Constructor.
44: */
45: public IsEmptyDataExpression() {
46: }
47:
48: /**
49: * Checks, whether the report has a data-source and wether the datasource is empty. A datasource is considered
50: * empty, if it contains no rows. The number of columns is not evaluated.
51: *
52: * @return the value of the function.
53: */
54: public Object getValue() {
55:
56: final ExpressionRuntime runtime = getRuntime();
57: if (runtime == null) {
58: return null;
59: }
60: final TableModel data = runtime.getData();
61: if (data == null) {
62: return null;
63: }
64: if (data.getRowCount() == 0) {
65: return Boolean.TRUE;
66: }
67: return Boolean.FALSE;
68: }
69: }
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