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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.databene.commons.iterator;
import org.databene.commons.ConfigurationError;
import org.databene.commons.StringUtil;
/**
* Iterates through another {@link TabularIterator},
* picking and possibly reordering a sub set of its columns.
* Created: 26.01.2012 18:33:10
* @since 0.5.14
* @author Volker Bergmann
*/
public class SelectiveTabularIterator extends IteratorProxy implements TabularIterator {
private String[] columnNames;
private int[] sourceIndexes;
public SelectiveTabularIterator(TabularIterator source, String[] columnNames) {
super(source);
String[] sourceColumnNames = source.getColumnNames();
if (columnNames != null) {
this.columnNames = columnNames;
this.sourceIndexes = new int[columnNames.length];
for (int i = 0; i < columnNames.length; i++) {
String columnName = columnNames[i];
int sourceIndex = StringUtil.indexOfIgnoreCase(columnName, sourceColumnNames);
if (sourceIndex < 0)
throw new ConfigurationError("Column '" + columnName + "' not defined in source: " + source);
this.sourceIndexes[i] = sourceIndex;
}
} else {
this.columnNames = sourceColumnNames;
this.sourceIndexes = null;
}
}
@Override
public String[] getColumnNames() {
return columnNames;
}
@Override
public Object[] next() {
Object[] sourceArray = super.next();
if (sourceIndexes == null)
return sourceArray;
Object[] result = new Object[sourceIndexes.length];
for (int i = 0; i < sourceIndexes.length; i++)
result[i] = (i < sourceArray.length ? sourceArray[sourceIndexes[i]] : null);
return result;
}
}