org.simpleframework.xml.core.ArrayFactory Maven / Gradle / Ivy
/*
* ArrayFactory.java July 2006
*
* Copyright (C) 2006, Niall Gallagher
*
* 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.
*
* 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.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.xml.core;
import java.lang.reflect.Array;
import org.simpleframework.xml.strategy.Value;
import org.simpleframework.xml.stream.InputNode;
/**
* The ArrayFactory is used to create object array
* types that are compatible with the field type. This simply
* requires the type of the array in order to instantiate that
* array. However, this also performs a check on the field type
* to ensure that the array component types are compatible.
*
* @author Niall Gallagher
*/
class ArrayFactory extends Factory {
/**
* Constructor for the ArrayFactory object. This is
* given the array component type as taken from the field type
* of the source object. Each request for an array will return
* an array which uses a compatible component type.
*
* @param context this is the context object for serialization
* @param field the array component type for the field object
*/
public ArrayFactory(Context context, Class field) {
super(context, field);
}
/**
* This is used to create a default instance of the field type. It
* is up to the subclass to determine how to best instantiate an
* object of the field type that best suits. This is used when the
* empty value is required or to create the default type instance.
*
* @return a type which is used to instantiate the collection
*/
@Override
public Object getInstance() throws Exception {
Class type = field.getComponentType();
if(type != null) {
return Array.newInstance(type, 0);
}
return null;
}
/**
* Creates the array type to use. This will use the provided
* XML element to determine the array type and provide a means
* for creating an array with the Value object. If
* the array size cannot be determined an exception is thrown.
*
* @param node this is the input node for the array element
*
* @return the object array type used for the instantiation
*/
public Instance getInstance(InputNode node) throws Exception {
Value value = getOverride(node);
if(value == null) {
throw new ElementException("Array length required for %s", field);
}
Class type = value.getType();
return getInstance(value, type);
}
/**
* Creates the array type to use. This will use the provided
* XML element to determine the array type and provide a means
* for creating an array with the Value object. If
* the array types are not compatible an exception is thrown.
*
* @param value this is the type object with the array details
* @param type this is the entry type for the array instance
*
* @return this object array type used for the instantiation
*/
private Instance getInstance(Value value, Class type) throws Exception {
Class expect = field.getComponentType();
if(!expect.isAssignableFrom(type)) {
throw new InstantiationException("Array of type %s cannot hold %s", expect, type);
}
return new ArrayInstance(value);
}
}