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/*
* Instance.java January 2007
*
* Copyright (C) 2007, Niall Gallagher
*
* 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.simpleframework.xml.core;
/**
* The Instance
object creates a type that is represented
* by an XML element. Typically the getInstance
method
* acts as a proxy to the classes new instance method, which takes no
* arguments. Simply delegating to Class.newInstance
will
* sometimes not be sufficient, is such cases reflectively acquiring
* the classes constructor may be required in order to pass arguments.
*
* @author Niall Gallagher
*
* @see org.simpleframework.xml.strategy.Value
*/
interface Instance {
/**
* This method is used to acquire an instance of the type that
* is defined by this object. If for some reason the type can
* not be instantiated an exception is thrown from this.
*
* @return an instance of the type this object represents
*/
Object getInstance() throws Exception;
/**
* This method is used acquire the value from the type and if
* possible replace the value for the type. If the value can
* not be replaced then an exception should be thrown. This
* is used to allow primitives to be inserted into a graph.
*
* @param value this is the value to insert as the type
*
* @return an instance of the type this object represents
*/
Object setInstance(Object value) throws Exception;
/**
* This is used to determine if the type is a reference type.
* A reference type is a type that does not require any XML
* deserialization based on its annotations. Values that are
* references could be substitutes objects or existing ones.
*
* @return this returns true if the object is a reference
*/
boolean isReference();
/**
* This is the type of the object instance that will be created
* by the getInstance
method. This allows the
* deserialization process to perform checks against the field.
*
* @return the type of the object that will be instantiated
*/
Class getType();
}