com.holonplatform.vaadin.flow.components

Interface ValueHolder<V,E extends ValueHolder.ValueChangeEvent<V>>

Type Parameters:

V - Value type

E - Value change event type

All Superinterfaces:

Serializable

All Known Subinterfaces:

Input<T>, MultiSelect<T>, PropertyInputForm, PropertyInputGroup, PropertyViewForm, PropertyViewGroup, SingleSelect<T>, ValidatableInput<T>, ValidatableMultiSelect<T>, ValidatableSingleSelect<T>, ViewComponent<V>

public interface ValueHolder<V,E extends ValueHolder.ValueChangeEvent<V>>
extends Serializable

Represents an object which holds a value and provide methods to handle such value.

Since:

5.2.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	ValueHolder.ValueChangeEvent<V> A ValueHolder.ValueChangeListener event.
static interface	ValueHolder.ValueChangeListener<V,E extends ValueHolder.ValueChangeEvent<V>> A listener for ValueHolder value change events.

Method Summary

Modifier and Type	Method and Description
com.holonplatform.core.Registration	addValueChangeListener(ValueHolder.ValueChangeListener<V,E> listener) Adds a value change listener, called when the value changes.
default void	clear() Clears this value holder.
default V	getEmptyValue() Returns the value that represents an empty value.
V	getValue() Gets the current value of this value holder.
default Optional<V>	getValueIfPresent() Gets the value as an Optional, which will be empty if the value holder is considered to be empty or the value is null.
default boolean	isEmpty() Returns whether this value holder is considered to be empty, according to its current value.
void	setValue(V value) Sets the value of this value holder.

Method Detail

setValue

void setValue(V value)

Sets the value of this value holder.

Parameters:

value - the value to set

Throws:

IllegalArgumentException - if the value is not valid

getValue

V getValue()

Gets the current value of this value holder.

Returns:

the current value

getValueIfPresent

default Optional<V> getValueIfPresent()

Gets the value as an Optional, which will be empty if the value holder is considered to be empty or the value is null.

Returns:

Optional value

getEmptyValue

default V getEmptyValue()

Returns the value that represents an empty value.

Returns:

the value that represents an empty value (null by default)

isEmpty

default boolean isEmpty()

Returns whether this value holder is considered to be empty, according to its current value.

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

Returns:

true if considered empty, false if not

clear

default void clear()

Clears this value holder.

By default, resets the value to the empty one.

addValueChangeListener

com.holonplatform.core.Registration addValueChangeListener(ValueHolder.ValueChangeListener<V,E> listener)

Adds a value change listener, called when the value changes.

Parameters:

listener - the value change listener to add (not null)

Returns:

a registration for the listener, which provides the remove operation