[1150] | 1 | // Copyright 2012 Georg-August-Universität Göttingen, Germany
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| 2 | //
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| 3 | // Licensed under the Apache License, Version 2.0 (the "License");
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| 4 | // you may not use this file except in compliance with the License.
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| 5 | // You may obtain a copy of the License at
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| 6 | //
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| 7 | // http://www.apache.org/licenses/LICENSE-2.0
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| 8 | //
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| 9 | // Unless required by applicable law or agreed to in writing, software
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| 10 | // distributed under the License is distributed on an "AS IS" BASIS,
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| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 12 | // See the License for the specific language governing permissions and
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| 13 | // limitations under the License.
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| 14 |
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| 15 | package de.ugoe.cs.autoquest.usability.util;
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| 16 |
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[1319] | 17 | import java.util.Collection;
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| 18 | import java.util.Collections;
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| 19 |
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[1150] | 20 | import org.apache.commons.lang.StringUtils;
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| 21 |
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[1152] | 22 | import de.ugoe.cs.autoquest.tasktrees.treeifc.ITask;
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[1319] | 23 | import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskInstance;
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[1163] | 24 | import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskVisitor;
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[1150] | 25 |
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| 26 | /**
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| 27 | * <p>
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[1217] | 28 | * Implementation of Null Object pattern {@link http://en.wikipedia.org/wiki/Null_Object_pattern}.
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[1150] | 29 | * </p>
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| 30 | *
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| 31 | * @author Alexander Deicke
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| 32 | */
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[1163] | 33 | public class NullTask implements ITask {
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[1150] | 34 |
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[1163] | 35 | private static final long serialVersionUID = 1236779392413787860L;
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| 36 |
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[1217] | 37 | /*
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| 38 | * (non-Javadoc)
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| 39 | *
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[1163] | 40 | * @see de.ugoe.cs.autoquest.tasktrees.treeifc.ITask#getId()
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| 41 | */
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| 42 | @Override
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| 43 | public int getId() {
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| 44 | return -1;
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| 45 | }
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[1217] | 46 |
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| 47 | /*
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| 48 | * (non-Javadoc)
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| 49 | *
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[1150] | 50 | * @see de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNode#getName()
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| 51 | */
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| 52 | public String getName() {
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| 53 | return StringUtils.EMPTY;
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| 54 | }
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| 55 |
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[1217] | 56 | /*
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| 57 | * (non-Javadoc)
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| 58 | *
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[1150] | 59 | * @see de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNode#getDescription()
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| 60 | */
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| 61 | public String getDescription() {
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| 62 | return StringUtils.EMPTY;
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| 63 | }
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| 64 |
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[1217] | 65 | /*
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| 66 | * (non-Javadoc)
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| 67 | *
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| 68 | * @see
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| 69 | * de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNode#equals(de.ugoe.cs.autoquest.tasktrees
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| 70 | * .treeifc.ITaskTreeNode)
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[1150] | 71 | */
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[1152] | 72 | public boolean equals(ITask task) {
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[1150] | 73 | return false;
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| 74 | }
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[1217] | 75 |
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| 76 | /*
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| 77 | * (non-Javadoc)
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| 78 | *
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[1150] | 79 | * @see java.lang.Object#clone()
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| 80 | */
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| 81 | @Override
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[1163] | 82 | public NullTask clone() {
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| 83 | return (NullTask) this;
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[1150] | 84 | }
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| 85 |
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[1217] | 86 | /*
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| 87 | * (non-Javadoc)
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| 88 | *
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| 89 | * @see
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| 90 | * de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNode#accept(de.ugoe.cs.autoquest.tasktrees
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| 91 | * .treeifc.NodeVisitor)
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[1150] | 92 | */
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[1163] | 93 | public void accept(ITaskVisitor visitor) {
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| 94 | // do nothing
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[1150] | 95 | }
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[1217] | 96 |
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[1319] | 97 | @Override
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| 98 | public Collection<ITaskInstance> getInstances() {
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| 99 | // return nothing
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| 100 | return Collections.emptyList();
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| 101 | }
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| 102 |
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[1150] | 103 | }
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