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## org.crosswire.common.history
Class History

    java.lang.Object
      org.crosswire.common.history.History

    public class History

extends Object

Maintains a navigable history of objects. This maintains a dated list of objects and a current navigation list.

Author:
  DM Smith [dmsmith555 at gmail dot com]
See Also:
  `for license details.
  The copyright to this program is held by it's authors.`

Field Summary
`private int` | `backCount` The number of elements in the "back" list.
`private Map` | `history` A map of elements that have been seen so far to when they have been seen.
`private EventListenerList` | `listeners` Listeners that are interested when history has changed.
`private List` | `nav` The elements that can be navigated.

Constructor Summary
`History()` Create an empty navigation and history list.

Method Summary
`void` | `add(Object obj)` Add an element to history.
`void` | `addHistoryListener(HistoryListener li)` Add a listener for history events.
`private void` | `fireHistoryChanged()` Kick of an event sequence
`Object` | `getCurrent()` Get the current item in the "back" list
`List` | `getNextList()` Get all the elements in the "forward" list.
`List` | `getPreviousList()` Get all the elements in "back" list.
`Object` | `go(int i)` Increments the current history item by the given amount.
`void` | `removeHistoryListener(HistoryListener li)` Remove a listener of history events.
`Object` | `select(int index)` Make a particular element in the navigation list the current item in history.
`private void` | `visit(Object obj)` Note that this object has been seen at this time.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### nav

    private List nav

  The elements that can be navigated.

### history

    private Map history

  A map of elements that have been seen so far to when they have been seen.

### backCount

    private int backCount

  The number of elements in the "back" list.

### listeners

    private EventListenerList listeners

  Listeners that are interested when history has changed.

Constructor Detail

### History

    public History()

  Create an empty navigation and history list.

Method Detail

### select

    public Object select(int index)

  Make a particular element in the navigation list the current item in history.

  Parameters:
    `index` - the index of item to make the last one in the back list, -1 (or lower) will put everything in the forward list. Indexes beyond the end of the list will put everything in the back list.

### add

    public void add(Object obj)

  Add an element to history. If there is any "forward" list, the element replaces it.

  Parameters:
    `obj` -

### getPreviousList

    public List getPreviousList()

  Get all the elements in "back" list.

  Returns:
    the elements in the back list.

### getNextList

    public List getNextList()

  Get all the elements in the "forward" list.

  Returns:
    the elements in the forward list.

### go

    public Object go(int i)

  Increments the current history item by the given amount. Positive numbers are forward. Negative numbers are back.

  Parameters:
    `i` - the distance to travel
  Returns:
    the item at the requested location, or at the end of the list if i is too big, or at the beginning of the list if i is too small, otherwise null.

### getCurrent

    public Object getCurrent()

  Get the current item in the "back" list

  Returns:
    the current item in the back list.

### addHistoryListener

    public void addHistoryListener(HistoryListener li)

  Add a listener for history events.

  Parameters:
    `li` - the interested listener

### removeHistoryListener

    public void removeHistoryListener(HistoryListener li)

  Remove a listener of history events.

  Parameters:
    `li` - the disinterested listener

### visit

    private void visit(Object obj)

  Note that this object has been seen at this time.

  Parameters:
    `obj` -

### fireHistoryChanged

    private void fireHistoryChanged()

  Kick of an event sequence

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| Copyright ? 2003-2006
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