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Java > Open Source Codes > org > apache > tools > ant > taskdefs > condition > Not


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18
19 package org.apache.tools.ant.taskdefs.condition;
20
21 import org.apache.tools.ant.BuildException;
22
23 /**
24  * <not> condition.
25  *
26  * Evaluates to true if the single condition nested into it is false
27  * and vice versa.
28  *
29  * @since Ant 1.4
30  */
31 public class Not extends ConditionBase implements Condition {
32
33     /**
34      * Evaluate condition
35      *
36      * @return true if the condition is true.
37      * @throws BuildException if the condition is not configured correctly.
38      */
39     public boolean eval() throws BuildException {
40         if (countConditions() > 1) {
41             throw new BuildException("You must not nest more than one "
42                 + "condition into <not>");
43         }
44         if (countConditions() < 1) {
45             throw new BuildException("You must nest a condition into <not>");
46         }
47         return !((Condition) getConditions().nextElement()).eval();
48     }
49
50 }
51
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