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 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package javax.smartcardio;

import java.util.*;

/**

 * The set of terminals supported by a TerminalFactory.

 * This class allows applications to enumerate the available CardTerminals,

 * obtain a specific CardTerminal, or wait for the insertion or removal of

 * cards.

 *

 * <p>This class is multi-threading safe and can be used by multiple

 * threads concurrently. However, this object keeps track of the card

 * presence state of each of its terminals. Multiple objects should be used

 * if independent calls to {@linkplain #waitForChange} are required.

 *

 * <p>Applications can obtain instances of this class by calling

 * {@linkplain TerminalFactory#terminals}.

 *

 * @see TerminalFactory

 * @see CardTerminal

 *

 * @since   1.6

 * @author  Andreas Sterbenz

 * @author  JSR 268 Expert Group

 */

public abstract class CardTerminals {

    /**

     * Constructs a new CardTerminals object.

     *

     * <p>This constructor is called by subclasses only. Application should

     * call {@linkplain TerminalFactory#terminals}

     * to obtain a CardTerminals object.

     */

    protected CardTerminals() {

        // empty

    }

    /**

     * Returns an unmodifiable list of all available terminals.

     *

     * @return an unmodifiable list of all available terminals.

     *

     * @throws CardException if the card operation failed

     */

    public List<CardTerminal> list() throws CardException {

         return list(State.ALL);

    }

    /**

     * Returns an unmodifiable list of all terminals matching the specified

     * state.

     *

     * <p>If state is {@link State#ALL State.ALL}, this method returns

     * all CardTerminals encapsulated by this object.

     * If state is {@link State#CARD_PRESENT State.CARD_PRESENT} or

     * {@link State#CARD_ABSENT State.CARD_ABSENT}, it returns all

     * CardTerminals where a card is currently present or absent, respectively.

     *

     * <p>If state is {@link State#CARD_INSERTION State.CARD_INSERTION} or

     * {@link State#CARD_REMOVAL State.CARD_REMOVAL}, it returns all

     * CardTerminals for which an insertion (or removal, respectively)

     * was detected during the last call to {@linkplain #waitForChange}.

     * If <code>waitForChange()</code> has not been called on this object,

     * <code>CARD_INSERTION</code> is equivalent to <code>CARD_PRESENT</code>

     * and <code>CARD_REMOVAL</code> is equivalent to <code>CARD_ABSENT</code>.

     * For an example of the use of <code>CARD_INSERTION</code>,

     * see {@link #waitForChange}.

     *

     * @param state the State

     * @return an unmodifiable list of all terminals matching the specified

     *   attribute.

     *

     * @throws NullPointerException if attr is null

     * @throws CardException if the card operation failed

     */

    public abstract List<CardTerminal> list(State state) throws CardException;

    /**

     * Returns the terminal with the specified name or null if no such

     * terminal exists.

     *

     * @return the terminal with the specified name or null if no such

     * terminal exists.

     *

     * @throws NullPointerException if name is null

     */

    public CardTerminal getTerminal(String name) {

        if (name == null) {

            throw new NullPointerException();

        }

        try {

            for (CardTerminal terminal : list()) {

                if (terminal.getName().equals(name)) {

                    return terminal;

                }

            }

            return null;

        } catch (CardException e) {

            return null;

        }

    }

    /**

     * Waits for card insertion or removal in any of the terminals of this

     * object.

     *

     * <p>This call is equivalent to calling

     * {@linkplain #waitForChange(long) waitForChange(0)}.

     *

     * @throws IllegalStateException if this <code>CardTerminals</code>

     *   object does not contain any terminals

     * @throws CardException if the card operation failed

     */

    public void waitForChange() throws CardException {

        waitForChange(0);

    }

    /**

     * Waits for card insertion or removal in any of the terminals of this

     * object or until the timeout expires.

     *

     * <p>This method examines each CardTerminal of this object.

     * If a card was inserted into or removed from a CardTerminal since the

     * previous call to <code>waitForChange()</code>, it returns

     * immediately.

     * Otherwise, or if this is the first call to <code>waitForChange()</code>

     * on this object, it blocks until a card is inserted into or removed from

     * a CardTerminal.

     *

     * <p>If <code>timeout</code> is greater than 0, the method returns after

     * <code>timeout</code> milliseconds even if there is no change in state.

     * In that case, this method returns <code>false</code>; otherwise it

     * returns <code>true</code>.

     *

     * <p>This method is often used in a loop in combination with

     * {@link #list(CardTerminals.State) list(State.CARD_INSERTION)},

     * for example:

     * <pre>

     *  TerminalFactory factory = ...;

     *  CardTerminals terminals = factory.terminals();

     *  while (true) {

     *      for (CardTerminal terminal : terminals.list(CARD_INSERTION)) {

     *          // examine Card in terminal, return if it matches

     *      }

     *      terminals.waitForChange();

     *  }</pre>

     *

     * @param timeout if positive, block for up to <code>timeout</code>

     *   milliseconds; if zero, block indefinitely; must not be negative

     * @return false if the method returns due to an expired timeout,

     *   true otherwise.

     *

     * @throws IllegalStateException if this <code>CardTerminals</code>

     *   object does not contain any terminals

     * @throws IllegalArgumentException if timeout is negative

     * @throws CardException if the card operation failed

     */

    public abstract boolean waitForChange(long timeout) throws CardException;

    /**

     * Enumeration of attributes of a CardTerminal.

     * It is used as a parameter to the {@linkplain CardTerminals#list} method.

     *

     * @since 1.6

     */

    public static enum State {

        /**

         * All CardTerminals.

         */

        ALL,

        /**

         * CardTerminals in which a card is present.

         */

        CARD_PRESENT,

        /**

         * CardTerminals in which a card is not present.

         */

        CARD_ABSENT,

        /**

         * CardTerminals for which a card insertion was detected during the

         * latest call to {@linkplain State#waitForChange waitForChange()}

         * call.

         */

        CARD_INSERTION,

        /**

         * CardTerminals for which a card removal was detected during the

         * latest call to {@linkplain State#waitForChange waitForChange()}

         * call.

         */

        CARD_REMOVAL,

    }

}