Interface HasValue<V>

Method Detail

• setValue

  void setValue​(V value)

  Sets the value of this object. If the new value is not equal to getValue(), fires a value change event. May throw IllegalArgumentException if the value is not acceptable.

  Implementation note: the implementing class should document whether null values are accepted or not.

  Parameters:

  value - the new value

  Throws:

  IllegalArgumentException - if the value is invalid

• getValue

  V getValue()

  Returns the current value of this object.

  Implementation note: the implementing class should document whether null values may be returned or not.

  Returns:

  the current value

• addValueChangeListener

  Registration addValueChangeListener​(HasValue.ValueChangeListener<V> listener)

  Adds a value change listener. The listener is called when the value of this HasValue is changed either by the user or programmatically.

  Parameters:

  listener - the value change listener, not null

  Returns:

  a registration for the listener

• getEmptyValue

  default V getEmptyValue()

  Returns the value that represents an empty value.

  By default HasValue is expected to support null as empty values. Specific implementations might not support this.

  Returns:

  empty value

  See Also:

  Binder#bind(HasValue, ValueProvider, Setter)

• getOptionalValue

  default Optional<V> getOptionalValue()

  Returns the current value of this object, wrapped in an Optional.

  The Optional will be empty if the value is null or isEmpty() returns true.

  Returns:

  the current value, wrapped in an Optional

• isEmpty

  default boolean isEmpty()

  Returns whether this HasValue is considered to be empty.

  By default this is an equality check between current value and empty value.

  Returns:

  true if considered empty; false if not

• setRequiredIndicatorVisible

  void setRequiredIndicatorVisible​(boolean requiredIndicatorVisible)

  Sets the required indicator visible or not.

  If set visible, it is visually indicated in the user interface.

  Parameters:

  requiredIndicatorVisible - true to make the required indicator visible, false if not

• isRequiredIndicatorVisible

  boolean isRequiredIndicatorVisible()

  Checks whether the required indicator is visible.

  Returns:

  true if visible, false if not

• setReadOnly

  void setReadOnly​(boolean readOnly)

  Sets the read-only mode of this HasValue to given mode. The user can't change the value when in read-only mode.

  A HasValue with a visual component in read-only mode typically looks visually different to signal to the user that the value cannot be edited.

  Parameters:

  readOnly - a boolean value specifying whether the component is put read-only mode or not

• isReadOnly

  boolean isReadOnly()

  Returns whether this HasValue is in read-only mode or not.

  Returns:

  false if the user can modify the value, true if not.

• clear

  default void clear()

  Resets the value to the empty one.

  This is just a shorthand for resetting the value, see the methods setValue(Object) and getEmptyValue().

  See Also:

  setValue(Object), getEmptyValue()

• getDefaultValidator

  default Validator<V> getDefaultValidator()

  Returns a validator that checks the internal state of the HasValue. This should be overridden for components with internal value conversion or validation, e.g. when the user is providing a string that has to be parsed into a date. An invalid input from user will be exposed to a Binder and can be seen as a validation failure.

  Returns:

  internal state validator

  Since:

  8.1

  See Also:

  Binder.validate()