# Class SetExpression<E>

java.lang.Object
javafx.beans.binding.SetExpression<E>

Type Parameters:
  `E` - the type of the `Set` elements

All Implemented Interfaces:
  `Iterable<E>`, `Collection<E>`, `Set<E>`, `Observable`, `ObservableObjectValue<ObservableSet<E>>`, `ObservableSetValue<E>`, `ObservableValue<ObservableSet<E>>`, `ObservableSet<E>`

Direct Known Subclasses:
  `ReadOnlySetProperty`, `SetBinding`

public abstract class SetExpression<E> extends Object implements ObservableSetValue<E>
`SetExpression` is an `ObservableSetValue` plus additional convenience methods to generate bindings in a fluent style.

A concrete sub-class of `SetExpression` has to implement the method `ObservableObjectValue.get()`, which provides the actual value of this expression.

If the wrapped list of a `SetExpression` is `null`, all methods implementing the `Set` interface will behave as if they were applied to an immutable empty set.

Since:
  JavaFX 2.1

- ## Property Summary

  Properties
  Type
  Property
  Description
  `abstract ReadOnlyBooleanProperty`
  `empty`
  A boolean property that is `true`, if the set is empty.
  `abstract ReadOnlyIntegerProperty`
  `size`
  An integer property that represents the size of the set.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `SetExpression()`
  Creates a default `SetExpression`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `add(E element)`
  `boolean`
  `addAll(Collection<? extends E> elements)`
  `StringBinding`
  `asString()`
  Creates a `StringBinding` that holds the value of the `SetExpression` turned into a `String`.
  `void`
  `clear()`
  `boolean`
  `contains(Object obj)`
  `boolean`
  `containsAll(Collection<?> objects)`
  `abstract ReadOnlyBooleanProperty`
  `emptyProperty()`
  A boolean property that is `true`, if the set is empty.
  `int`
  `getSize()`
  The size of the set
  `ObservableSet<E>`
  `getValue()`
  Returns the current value of this `ObservableValue`
  `boolean`
  `isEmpty()`
  Gets the value of the `empty` property.
  `BooleanBinding`
  `isEqualTo(ObservableSet<?> other)`
  Creates a new `BooleanBinding` that holds `true` if this set is equal to another `ObservableSet`.
  `BooleanBinding`
  `isNotEqualTo(ObservableSet<?> other)`
  Creates a new `BooleanBinding` that holds `true` if this set is not equal to another `ObservableSet`.
  `BooleanBinding`
  `isNotNull()`
  Creates a new `BooleanBinding` that holds `true` if the wrapped set is not `null`.
  `BooleanBinding`
  `isNull()`
  Creates a new `BooleanBinding` that holds `true` if the wrapped set is `null`.
  `Iterator<E>`
  `iterator()`
  `boolean`
  `remove(Object obj)`
  `boolean`
  `removeAll(Collection<?> objects)`
  `boolean`
  `retainAll(Collection<?> objects)`
  `static <E> SetExpression<E>`
  `setExpression(ObservableSetValue<E> value)`
  Returns a `SetExpression` that wraps a `ObservableSetValue`.
  `int`
  `size()`
  `abstract ReadOnlyIntegerProperty`
  `sizeProperty()`
  An integer property that represents the size of the set.
  `Object[]`
  `toArray()`
  `<T> T[]`
  `toArray(T[] array)`

  ### Methods declared in class java.lang.Object

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

  ### Methods declared in interface java.util.Collection

  `parallelStream, removeIf, stream, toArray`

  ### Methods declared in interface java.lang.Iterable

  `forEach`

  ### Methods declared in interface javafx.beans.Observable

  `addListener, removeListener, subscribe`

  ### Methods declared in interface javafx.beans.value.ObservableObjectValue

  `get`

  ### Methods declared in interface javafx.collections.ObservableSet

  `addListener, removeListener`

  ### Methods declared in interface javafx.beans.value.ObservableValue

  `addListener, flatMap, map, orElse, removeListener, subscribe, subscribe, when`

  ### Methods declared in interface java.util.Set

  `equals, hashCode, spliterator`

- ## Property Details

  - ### size

    public abstract ReadOnlyIntegerProperty sizeProperty
    An integer property that represents the size of the set.
    See Also:
      - `getSize()`
      - `sizeProperty()`

  - ### empty

    public abstract ReadOnlyBooleanProperty emptyProperty
    A boolean property that is `true`, if the set is empty.
    See Also:
      - `isEmpty()`
      - `emptyProperty()`

- ## Constructor Details

  - ### SetExpression

    public SetExpression()
    Creates a default `SetExpression`.

- ## Method Details

  - ### getValue

    public ObservableSet<E> getValue()
    Description copied from interface: `ObservableValue`
    Returns the current value of this `ObservableValue`
    Specified by:
      `getValue` in interface `ObservableValue<E>`
    Returns:
      The current value

  - ### setExpression

    public static <E> SetExpression<E> setExpression(ObservableSetValue<E> value)
    Returns a `SetExpression` that wraps a `ObservableSetValue`. If the `ObservableSetValue` is already a `SetExpression`, it will be returned. Otherwise a new `SetBinding` is created that is bound to the `ObservableSetValue`.
    Type Parameters:
      `E` - the type of the `Set` elements
    Parameters:
      `value` - The source `ObservableSetValue`
    Returns:
      A `SetExpression` that wraps the `ObservableSetValue` if necessary
    Throws:
      `NullPointerException` - if `value` is `null`

  - ### getSize

    public int getSize()
    The size of the set
    Returns:
      the size

  - ### sizeProperty

    public abstract ReadOnlyIntegerProperty sizeProperty()
    An integer property that represents the size of the set.
    Returns:
      the property
    See Also:
      - `getSize()`

  - ### emptyProperty

    public abstract ReadOnlyBooleanProperty emptyProperty()
    A boolean property that is `true`, if the set is empty.
    Returns:
      the `ReadOnlyBooleanProperty`
    See Also:
      - `isEmpty()`

  - ### isEqualTo

    public BooleanBinding isEqualTo(ObservableSet<?> other)
    Creates a new `BooleanBinding` that holds `true` if this set is equal to another `ObservableSet`.
    Parameters:
      `other` - the other `ObservableSet`
    Returns:
      the new `BooleanBinding`
    Throws:
      `NullPointerException` - if `other` is `null`

  - ### isNotEqualTo

    public BooleanBinding isNotEqualTo(ObservableSet<?> other)
    Creates a new `BooleanBinding` that holds `true` if this set is not equal to another `ObservableSet`.
    Parameters:
      `other` - the other `ObservableSet`
    Returns:
      the new `BooleanBinding`
    Throws:
      `NullPointerException` - if `other` is `null`

  - ### isNull

    public BooleanBinding isNull()
    Creates a new `BooleanBinding` that holds `true` if the wrapped set is `null`.
    Returns:
      the new `BooleanBinding`

  - ### isNotNull

    public BooleanBinding isNotNull()
    Creates a new `BooleanBinding` that holds `true` if the wrapped set is not `null`.
    Returns:
      the new `BooleanBinding`

  - ### asString

    public StringBinding asString()
    Creates a `StringBinding` that holds the value of the `SetExpression` turned into a `String`. If the value of this `SetExpression` changes, the value of the `StringBinding` will be updated automatically.
    Returns:
      the new `StringBinding`

  - ### size

    public int size()
    Specified by:
      `size` in interface `Collection<E>`
    Specified by:
      `size` in interface `Set<E>`

  - ### isEmpty

    public boolean isEmpty()
    Gets the value of the `empty` property.
    Specified by:
      `isEmpty` in interface `Collection<E>`
    Specified by:
      `isEmpty` in interface `Set<E>`
    Property description:
      A boolean property that is `true`, if the set is empty.
    Returns:
      the value of the `empty` property
    See Also:
      - `emptyProperty()`

  - ### contains

    public boolean contains(Object obj)
    Specified by:
      `contains` in interface `Collection<E>`
    Specified by:
      `contains` in interface `Set<E>`

  - ### iterator

    public Iterator<E> iterator()
    Specified by:
      `iterator` in interface `Collection<E>`
    Specified by:
      `iterator` in interface `Iterable<E>`
    Specified by:
      `iterator` in interface `Set<E>`

  - ### toArray

    public Object[] toArray()
    Specified by:
      `toArray` in interface `Collection<E>`
    Specified by:
      `toArray` in interface `Set<E>`

  - ### toArray

    public <T> T[] toArray(T[] array)
    Specified by:
      `toArray` in interface `Collection<E>`
    Specified by:
      `toArray` in interface `Set<E>`

  - ### add

    public boolean add(E element)
    Specified by:
      `add` in interface `Collection<E>`
    Specified by:
      `add` in interface `Set<E>`

  - ### remove

    public boolean remove(Object obj)
    Specified by:
      `remove` in interface `Collection<E>`
    Specified by:
      `remove` in interface `Set<E>`

  - ### containsAll

    public boolean containsAll(Collection<?> objects)
    Specified by:
      `containsAll` in interface `Collection<E>`
    Specified by:
      `containsAll` in interface `Set<E>`

  - ### addAll

    public boolean addAll(Collection<? extends E> elements)
    Specified by:
      `addAll` in interface `Collection<E>`
    Specified by:
      `addAll` in interface `Set<E>`

  - ### removeAll

    public boolean removeAll(Collection<?> objects)
    Specified by:
      `removeAll` in interface `Collection<E>`
    Specified by:
      `removeAll` in interface `Set<E>`

  - ### retainAll

    public boolean retainAll(Collection<?> objects)
    Specified by:
      `retainAll` in interface `Collection<E>`
    Specified by:
      `retainAll` in interface `Set<E>`

  - ### clear

    public void clear()
    Specified by:
      `clear` in interface `Collection<E>`
    Specified by:
      `clear` in interface `Set<E>`