Collections and Concurrency - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 285

Figure 7-4. Key interfaces that support the JavaFX observable array

Unlike for the ObservableList , ObservableMap , and ObservableSet interfaces, the ObservableArray interface
does not implement any Java collections framework interfaces. The following methods on the ObservableArray
interface allow you to register and unregister ArrayChangeListeners :

addListener(ArrayChangeListener<T> listener) •

removeListener(ArrayChangeListener<T> listener)
The following additional methods on ObservableArray give you control of the underlying primitive arrays:

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resize(int size) •

ensureCapacity(int capacity)

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trimToSize() •

clear() •

size()
These methods deal with the capacity and size of an ObservableArray . The capacity is the length of the underlying
primitive array. The size is the number of elements that actually contain application data. The capacity is always greater
than or equal to the size. The ensureCapacity() method allocates a new underlying primitive array if the length of
the current underlying primitive array is less than the desired new capacity. The resize() method changes the size of
ObservableArray . If the new size is greater than the current capacity, the capacity is increased. If the new size is greater
than the current size, the additional elements are filled with zero. If the new size is less than the current size, resize()
does not actually shrink the array, but the “lost” elements are filled with zero. The trimToSize() method replaces the
underlying primitive array with one whose length is the same as the size of the ObservableArray . The clear() method
resizes the ObservableArray to size zero. The size() method returns the current size of the ObservableArray .

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