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package org.hisp.dhis.util;
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* Copyright (c) 2004-2007, University of Oslo
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of the HISP project nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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import java.lang.reflect.Method;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.HashMap;
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import java.util.List;
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* @author Torgeir Lorange Ostby
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* @version $Id: CollectionUtils.java 2869 2007-02-20 14:26:09Z andegje $
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public class CollectionUtils
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* Creates a map with the elements of the collection as values using the
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* specified keyMethod to obtain the key from the elements.
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@SuppressWarnings( "unchecked" )
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public static <K, T> Map<K, T> createMap( Collection<T> collection, String keyMethod )
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Map<K, T> map = new HashMap<K, T>( collection.size() );
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if ( collection.isEmpty() )
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Class elementClass = collection.iterator().next().getClass();
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getKeyMethod = elementClass.getMethod( keyMethod, new Class[0] );
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throw new RuntimeException( "Failed to get key method", e );
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for ( T element : collection )
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key = (K) getKeyMethod.invoke( element, (Object[]) null );
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throw new RuntimeException( "Failed to get key", e );
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map.put( key, element );
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* Creates a list of values extracted from the provided list using the
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* specified value method, keeping the order of the provided list.
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@SuppressWarnings( "unchecked" )
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public static <K, T> List<K> createList( List<T> list, String valueMethod )
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List<K> valueList = new ArrayList<K>( list.size() );
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Class elementClass = list.iterator().next().getClass();
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Method getValueMethod;
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getValueMethod = elementClass.getMethod( valueMethod, new Class[0] );
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catch ( Exception e )
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throw new RuntimeException( "Failed to get key method", e );
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for ( T element : list )
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value = (K) getValueMethod.invoke( element, (Object[]) null );
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catch ( Exception e )
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throw new RuntimeException( "Failed to get key", e );
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valueList.add( value );