org.simpleframework.xml.core.Instance Maven / Gradle / Ivy
/*
* Instance.java January 2007
*
* Copyright (C) 2007, 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;
/**
* 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
*/
public 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
*/
public 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
*/
public 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
*/
public Class getType();
}