/*
 * 
 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * The contents of this file are subject to the Sun Community Source
 * License v3.0/Jini Technology Specific Attachment v 1.0 (the
 * "License"). You may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 * http://wwws.sun.com/software/jini/licensing/SCSL3_JiniTSA1.html.
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Reference Code is Jini Technology Core Platform code, v2.0. The
 * Developer of the Reference Code is Sun Microsystems, Inc.
 * 
 * Contributor(s): Sun Microsystems, Inc.
 * 
 * The contents of this file comply with the Jini Technology Core
 * Platform Compatibility Kit, v2.0A.
 * 
 * Tester(s): Sun Microsystems, Inc.
 * 
 * Test Platform(s):
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Solaris(TM)SPARC/x86
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Linux (Intel x86)
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Windows (Intel Platform)
 * 
 */

package net.jini.security.proxytrust;

import java.rmi.RemoteException;
import java.util.NoSuchElementException;

/**
 * A simple <code>ProxyTrustIterator</code> that produces a single object
 * as the only element of the iteration.
 *
 * @author Sun Microsystems, Inc.
 * 
 * @since 2.0
 */
public class SingletonProxyTrustIterator implements ProxyTrustIterator {
    /** The object to produce */
    private Object obj;
    /** True if setException can be called */
    private boolean settable = false;

    /**
     * Creates an instance with the specified object to use as the only
     * element of the iteration.
     *
     * @param obj the object to use as the element of the iteration
     * @throws NullPointerException if the argument is <code>null</code>
     */
    public SingletonProxyTrustIterator(Object obj) {
	if (obj == null) {
	    throw new NullPointerException("cannot be null");
	}
	this.obj = obj;
    }

    public synchronized boolean hasNext() {
	settable = false;
	return obj != null;
    }

    /**
     * @throws NoSuchElementException {@inheritDoc}
     */
    public synchronized Object next() {
	if (obj == null) {
	    throw new NoSuchElementException();
	}
	settable = true;
	Object res = obj;
	obj = null;
	return res;
    }

    /**
     * @throws NullPointerException {@inheritDoc}
     * @throws IllegalStateException {@inheritDoc}
     */
    public synchronized void setException(RemoteException e) {
	if (e == null) {
	    throw new NullPointerException("exception cannot be null");
	} else if (!settable) {
	    throw new IllegalStateException();
	}
	settable = false;
    }
}
