Module javafx.base

Package javafx.collections

Class ObservableListBase<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

javafx.collections.ObservableListBase<E>

Type Parameters:

E - the type of the elements contained in the List

All Implemented Interfaces:

Iterable<E>, Collection<E>, List<E>, Observable, ObservableList<E>

Direct Known Subclasses:

ModifiableObservableListBase, TransformationList

public abstract class ObservableListBase<E>
extends AbstractList<E>
implements ObservableList<E>

Abstract class that serves as a base class for ObservableList implementations. The base class provides two functionalities for the implementing classes.

• Listener handling by implementing addListener and removeListener methods. fireChange(javafx.collections.ListChangeListener.Change) method is provided for notifying the listeners with a Change object.
• Methods for building up a ListChangeListener.Change object. There are various methods called next*, like nextAdd(int, int) for new items in the lists or nextRemove(int, java.lang.Object) for an item being removed from the list.

  These methods must be always enclosed in beginChange() and endChange() block.

  See the example below.

The following example shows how the Change build-up works:

  public void removeOddIndexes() {
      beginChange();
      try {
          for (int i = 1; i < size(); ++i) {
              remove(i);
          }
      } finally {
          endChange();
      }
  }

  public void remove(int i) {
      beginChange();
      try {
          E removed = ... //do some stuff that will actually remove the element at index i
          nextRemove(i, removed);
      } finally {
          endChange();
      }
  }

 

The try/finally blocks in the example are needed only if there's a possibility for an exception to occur inside a beginChange() / endChange() block

Note: If you want to create modifiable ObservableList implementation, consider using ModifiableObservableListBase as a superclass.

Note: In order to create list with sequential access, you should override AbstractList.listIterator(), AbstractList.iterator() methods and use them in AbstractList.get(int), Collection.size() and other methods accordingly.

Since:

JavaFX 8.0

See Also:

ObservableList, ListChangeListener.Change, ModifiableObservableListBase

Field Summary

Fields declared in class java.util.AbstractList

modCount

Constructor Summary

Constructors

Constructor	Description
ObservableListBase()

Method Summary

Modifier and Type	Method	Description
protected void	beginChange()	Begins a change block.
protected void	endChange()	Ends the change block.
protected void	fireChange(ListChangeListener.Change<? extends E> change)	Notifies all listeners of a change
protected boolean	hasListeners()	Returns true if there are some listeners registered for this list.
protected void	nextAdd(int from, int to)	Adds a new add operation to the change.
protected void	nextPermutation(int from, int to, int[] perm)	Adds a new permutation operation to the change.
protected void	nextRemove(int idx, E removed)	Adds a new remove operation to the change with single item removed.
protected void	nextRemove(int idx, List<? extends E> removed)	Adds a new remove operation to the change with multiple items removed.
protected void	nextReplace(int from, int to, List<? extends E> removed)	Adds a new replace operation to the change.
protected void	nextSet(int idx, E old)	Adds a new set operation to the change.
protected void	nextUpdate(int pos)	Adds a new update operation to the change.

Methods declared in class java.util.AbstractCollection

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray, toString

Methods declared in class java.util.AbstractList

add, add, addAll, clear, equals, get, hashCode, indexOf, iterator, lastIndexOf, listIterator, listIterator, remove, removeRange, set, subList

Methods declared in interface java.util.Collection

parallelStream, removeIf, stream

Methods declared in interface java.lang.Iterable

forEach

Methods declared in interface java.util.List

add, add, addAll, addAll, clear, contains, containsAll, equals, get, hashCode, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, replaceAll, retainAll, set, size, sort, spliterator, subList, toArray, toArray

Methods declared in class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods declared in interface javafx.beans.Observable

addListener, removeListener

Methods declared in interface javafx.collections.ObservableList

addAll, addListener, filtered, remove, removeAll, removeListener, retainAll, setAll, setAll, sorted, sorted

Constructor Detail

ObservableListBase

public ObservableListBase()

Method Detail

nextUpdate

protected final void nextUpdate(int pos)

Adds a new update operation to the change.

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

pos - the position in the list where the updated element resides.

nextSet

protected final void nextSet(int idx,
                             E old)

Adds a new set operation to the change. Equivalent to nextRemove(idx); nextAdd(idx, idx + 1); .

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

idx - the index of the item that was set

old - the old value at the idx position.

nextReplace

protected final void nextReplace(int from,
                                 int to,
                                 List<? extends E> removed)

Adds a new replace operation to the change. Equivalent to nextRemove(from, removed); nextAdd(from, to);

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

from - the index where the items were replaced

to - the end index (exclusive) of the range where the new items reside

removed - the list of items that were removed

nextRemove

protected final void nextRemove(int idx,
                                List<? extends E> removed)

Adds a new remove operation to the change with multiple items removed.

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

idx - the index where the items were removed

removed - the list of items that were removed

nextRemove

protected final void nextRemove(int idx,
                                E removed)

Adds a new remove operation to the change with single item removed.

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

idx - the index where the item was removed

removed - the item that was removed

nextPermutation

protected final void nextPermutation(int from,
                                     int to,
                                     int[] perm)

Adds a new permutation operation to the change. The permutation on index "i" contains the index, where the item from the index "i" was moved.

It's not necessary to provide the smallest permutation possible. It's correct to always call this method with nextPermutation(0, size(), permutation);

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

from - marks the beginning (inclusive) of the range that was permutated

to - marks the end (exclusive) of the range that was permutated

perm - the permutation in that range. Even if from != 0, the array should contain the indexes of the list. Therefore, such permutation would not contain indexes of range (0, from)

nextAdd

protected final void nextAdd(int from,
                             int to)

Adds a new add operation to the change. There's no need to provide the list of added items as they can be found directly in the list under the specified indexes.

Note: needs to be called inside beginChange() / endChange() block.

Note: needs to reflect the current state of the list.

Parameters:

from - marks the beginning (inclusive) of the range that was added

to - marks the end (exclusive) of the range that was added

beginChange

protected final void beginChange()

Begins a change block. Must be called before any of the next* methods is called. For every beginChange(), there must be a corresponding endChange() call.

beginChange() calls can be nested in a beginChange()/endChange() block.

See Also:

endChange()

endChange

protected final void endChange()

Ends the change block. If the block is the outer-most block for the ObservableList, the Change is constructed and all listeners are notified.

Ending a nested block doesn't fire a notification.

See Also:

beginChange()

fireChange

protected final void fireChange(ListChangeListener.Change<? extends E> change)

Notifies all listeners of a change

Parameters:

change - an object representing the change that was done

hasListeners

protected final boolean hasListeners()

Returns true if there are some listeners registered for this list.

Returns:

true if there is a listener for this list