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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.

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 waitForChange are required. 
Applications can obtain instances of this class by calling TerminalFactory.terminals. 
Author: Andreas Sterbenz,  JSR 268 Expert Group
See Also:
Since:  1.6
/**
 * 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.

This constructor is called by subclasses only. Application should call TerminalFactory.terminals to obtain a CardTerminals object. 
/**
     * 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.

Throws:
Returns:an unmodifiable list of all available terminals.
/**
     * 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.

If state is State.ALL, this method returns all CardTerminals encapsulated by this object. If state is State.CARD_PRESENT or State.CARD_ABSENT, it returns all CardTerminals where a card is currently present or absent, respectively. 
If state is State.CARD_INSERTION or State.CARD_REMOVAL, it returns all CardTerminals for which an insertion (or removal, respectively) was detected during the last call to waitForChange. If waitForChange() has not been called on this object,
CARD_INSERTION is equivalent to CARD_PRESENT
and CARD_REMOVAL is equivalent to CARD_ABSENT.
For an example of the use of CARD_INSERTION, see waitForChange. 
Params:
  • state – the State
Throws:
Returns:an unmodifiable list of all terminals matching the specified
  attribute.
/**
     * 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.

Throws:
Returns:the terminal with the specified name or null if no such
terminal exists.
/**
     * 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.

This call is equivalent to calling waitForChange(0). 
Throws:
/**
     * 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.

This method examines each CardTerminal of this object.
If a card was inserted into or removed from a CardTerminal since the
previous call to waitForChange(), it returns
immediately.
Otherwise, or if this is the first call to waitForChange()
on this object, it blocks until a card is inserted into or removed from
a CardTerminal.

If timeout is greater than 0, the method returns after
timeout milliseconds even if there is no change in state.
In that case, this method returns false; otherwise it
returns true.

This method is often used in a loop in combination with list(State.CARD_INSERTION), for example: 
 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();
 }


Params:
  • timeout – if positive, block for up to timeout
  milliseconds; if zero, block indefinitely; must not be negative
Throws:
Returns:false if the method returns due to an expired timeout,
  true otherwise.
/**
     * 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 CardTerminals.list method. 
Since:1.6
/**
     * 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.
         */
        ALL,
        
CardTerminals in which a card is present.

/**
         * CardTerminals in which a card is present.
         */
        CARD_PRESENT,
        
CardTerminals in which a card is not present.

/**
         * CardTerminals in which a card is not present.
         */
        CARD_ABSENT,
        
CardTerminals for which a card insertion was detected during the latest call to waitForChange() call. 
/**
         * 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 waitForChange() call. 
/**
         * CardTerminals for which a card removal was detected during the
         * latest call to {@linkplain State#waitForChange waitForChange()}
         * call.
         */
        CARD_REMOVAL,
    }

}