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The main module contains the GeoTools public interfaces that are used by
other GeoTools modules (and GeoTools applications). Where possible we make
use industry standard terms as provided by OGC and ISO standards.
The formal GeoTools public api consists of gt-metadata, jts and the gt-main module.
The main module contains the default implementations that are available provided
to other GeoTools modules using our factory system. Factories are obtained from
an appropriate FactoryFinder, giving applications a chance configure the factory
used using the Factory Hints facilities.
FilterFactory ff = CommonFactoryFinder.getFilterFactory();
Expression expr = ff.add( expression1, expression2 );
If you find yourself using implementation specific classes chances are you doing it wrong:
Expression expr = new AddImpl( expression1, expressiom2 );
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/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2002-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.data.util;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import org.geotools.util.Converter;
import org.geotools.util.ConverterFactory;
import org.geotools.util.factory.Hints;
/**
* Converts among arrays and different collection classes.
*
* THe following conversions are supported:
*
*
* - Collection to Collection where collections are different types ( ex list to set )
*
- Collection to Array
*
- Array to Collection
*
- Array to Array where the declared type of the target array is assignable from the declared
* type of the source array
*
*
* @author Justin Deoliveira, The Open Planning Project
*/
public class CollectionConverterFactory implements ConverterFactory {
/** Converter for collection to collection */
protected static final Converter CollectionToCollection =
new Converter() {
public Object convert(Object source, Class target) throws Exception {
// if source is already an instance nevermind
if (target.isInstance(source)) {
return source;
}
// dynamically create and add
Collection converted = newCollection(target);
if (converted != null) {
converted.addAll((Collection) source);
}
return converted;
}
};
/** Converter for collection to array. */
protected static final Converter CollectionToArray =
new Converter() {
public Object convert(Object source, Class target) throws Exception {
Collection s = (Collection) source;
Object array = Array.newInstance(target.getComponentType(), s.size());
try {
int x = 0;
for (Iterator i = s.iterator(); i.hasNext(); x++) {
Array.set(array, x, i.next());
}
return array;
} catch (Exception e) {
// Means an incompatable type assignment
}
return null;
}
};
/** Converter for array to collection. */
protected static final Converter ArrayToCollection =
new Converter() {
public Object convert(Object source, Class target) throws Exception {
Collection collection = newCollection(target);
if (collection != null) {
int length = Array.getLength(source);
for (int i = 0; i < length; i++) {
collection.add(Array.get(source, i));
}
}
return collection;
}
};
/** Converter for array to array. */
protected static final Converter ArrayToArray =
new Converter() {
public Object convert(Object source, Class target) throws Exception {
// get the individual component types
Class s = source.getClass().getComponentType();
Class t = target.getComponentType();
// make sure the source can be assiigned to the target
if (t.isAssignableFrom(s)) {
int length = Array.getLength(source);
Object converted = Array.newInstance(t, length);
for (int i = 0; i < length; i++) {
Array.set(converted, i, Array.get(source, i));
}
return converted;
}
return null;
}
};
protected static Collection newCollection(Class target) throws Exception {
if (target.isInterface()) {
// try the common ones
if (List.class.isAssignableFrom(target)) {
return new ArrayList();
}
if (SortedSet.class.isAssignableFrom(target)) {
return new TreeSet();
} else if (Set.class.isAssignableFrom(target)) {
return new HashSet();
}
// could not figure out
return null;
} else {
// instantiate directly
return (Collection) target.getDeclaredConstructor().newInstance();
}
}
public Converter createConverter(Class source, Class target, Hints hints) {
if ((Collection.class.isAssignableFrom(source) || source.isArray())
&& (Collection.class.isAssignableFrom(target) || target.isArray())) {
// both collections?
if (Collection.class.isAssignableFrom(source)
&& Collection.class.isAssignableFrom(target)) {
return CollectionToCollection;
}
// both arrays?
if (source.isArray() && target.isArray()) {
return ArrayToArray;
}
// collection to array?
if (Collection.class.isAssignableFrom(source) && target.isArray()) {
return CollectionToArray;
}
// array to collection?
if (source.isArray() && Collection.class.isAssignableFrom(target)) {
return ArrayToCollection;
}
}
return null;
}
}
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