# Class CardTerminals

java.lang.Object
javax.smartcardio.CardTerminals

public abstract class CardTerminals extends Object
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().

Since:
  1.6
See Also:
  - `TerminalFactory`
  - `CardTerminal`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static enum`
  `CardTerminals.State`
  Enumeration of attributes of a CardTerminal.

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `CardTerminals()`
  Constructs a new CardTerminals object.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `CardTerminal`
  `getTerminal(String name)`
  Returns the terminal with the specified name or null if no such terminal exists.
  `List<CardTerminal>`
  `list()`
  Returns an unmodifiable list of all available terminals.
  `abstract List<CardTerminal>`
  `list(CardTerminals.State state)`
  Returns an unmodifiable list of all terminals matching the specified state.
  `void`
  `waitForChange()`
  Waits for card insertion or removal in any of the terminals of this object.
  `abstract boolean`
  `waitForChange(long timeout)`
  Waits for card insertion or removal in any of the terminals of this object or until the timeout expires.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### CardTerminals

    protected CardTerminals()
    Constructs a new CardTerminals object.

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

- ## Method Details

  - ### list

    public List<CardTerminal> list() throws CardException
    Returns an unmodifiable list of all available terminals.
    Returns:
      an unmodifiable list of all available terminals.
    Throws:
      `CardException` - if the card operation failed

  - ### list

    public abstract List<CardTerminal> list(CardTerminals.State state) throws CardException
    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()`.

    Parameters:
      `state` - the State
    Returns:
      an unmodifiable list of all terminals matching the specified state.
    Throws:
      `NullPointerException` - if state is null
      `CardException` - if the card operation failed

  - ### getTerminal

    public CardTerminal getTerminal(String name)
    Returns the terminal with the specified name or null if no such terminal exists.
    Parameters:
      `name` - the terminal name
    Returns:
      the terminal with the specified name or null if no such terminal exists.
    Throws:
      `NullPointerException` - if name is null

  - ### waitForChange

    public void waitForChange() throws CardException
    Waits for card insertion or removal in any of the terminals of this object.

    This call is equivalent to calling waitForChange(0).

    Throws:
      `IllegalStateException` - if this `CardTerminals` object does not contain any terminals
      `CardException` - if the card operation failed

  - ### waitForChange

    public abstract boolean waitForChange(long timeout) throws CardException
    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();
         }

    Parameters:
      `timeout` - if positive, block for up to `timeout` milliseconds; if zero, block indefinitely; must not be negative
    Returns:
      false if the method returns due to an expired timeout, true otherwise.
    Throws:
      `IllegalStateException` - if this `CardTerminals` object does not contain any terminals
      `IllegalArgumentException` - if timeout is negative
      `CardException` - if the card operation failed