Package com.vaadin.flow.component

Interface HasComponents

All Superinterfaces:

HasElement, HasEnabled, Serializable

All Known Subinterfaces:

FlexComponent, HasItemComponents<T>, HasItemsAndComponents<T>, HasOrderedComponents

All Known Implementing Classes:

Abbr, AccordionPanel, Anchor, Article, Aside, Board, Card, CheckboxGroup, Code, ConfirmDialog, DescriptionList, DescriptionList.Description, DescriptionList.Term, Details, Dialog, Dialog.DialogFooter, Dialog.DialogHeader, Div, Emphasis, FieldSet, FieldSet.Legend, FlexLayout, Footer, FormLayout, FormLayout.FormItem, FormLayout.FormRow, GridMenuItem, H1, H2, H3, H4, H5, H6, Header, HorizontalLayout, HtmlContainer, HtmlObject, Image, ListBox, ListBoxBase, ListItem, Main, MenuItem, MenuItemBase, MultiSelectListBox, NativeButton, NativeDetails.Summary, NativeLabel, NativeTable, NativeTableBody, NativeTableCaption, NativeTableCell, NativeTableFooter, NativeTableHeader, NativeTableHeaderCell, NativeTableRow, Nav, Notification, OrderedList, Paragraph, Popover, Pre, RouterLink, Row, Section, Select, Span, Tab, UI, UnorderedList, VerticalLayout, WebComponentUI

public interface HasComponents
extends HasElement, HasEnabled

A component to which the user can add and remove child components. Component in itself provides basic support for child components that are manually added as children of an element belonging to the component. This interface provides an explicit API for components that explicitly support adding and removing arbitrary child components.

HasComponents is generally implemented by layouts or components whose primary function is to host child components. It isn't, for example, implemented by non-layout components such as fields.

The default implementations assume that children are attached to HasElement.getElement(). Override all methods in this interface if the components should be added to some other element.

Since:

1.0

Author:

Vaadin Ltd

Method Summary

Modifier and Type	Method	Description
default void	add(Component... components)	Adds the given components as children of this component.
default void	add(String text)	Add the given text as a child of this component.
default void	add(Collection<Component> components)	Adds the given components as children of this component.
default void	addComponentAsFirst(Component component)	Adds the given component as the first child of this component.
default void	addComponentAtIndex(int index, Component component)	Adds the given component as a child of this component at the specific index.
default <T extends @Nullable Object, S extends Signal<T>> void	bindChildren(Signal<List<S>> list, SerializableFunction<S,Component> childFactory)	Binds a list Signal to this component using a child component factory.
default void	remove(Component... components)	Removes the given child components from this component.
default void	remove(Collection<Component> components)	Removes the given child components from this component.
default void	removeAll()	Removes all contents from this component, including child components, text content as well as child elements that have been added directly to this component using the Element API.

Methods inherited from interface com.vaadin.flow.component.HasElement

getElement

Methods inherited from interface com.vaadin.flow.component.HasEnabled

bindEnabled, isEnabled, setEnabled

Method Details

add

default void add(Component... components)

Adds the given components as children of this component.

In case any of the specified components has already been added to another parent, it will be removed from there and added to this one.

Parameters:

components - the components to add

add

default void add(Collection<Component> components)

Adds the given components as children of this component.

In case any of the specified components has already been added to another parent, it will be removed from there and added to this one.

Parameters:

components - the components to add

add

default void add(String text)

Add the given text as a child of this component.

Parameters:

text - the text to add, not null

remove

default void remove(Component... components)

Removes the given child components from this component.

Parameters:

components - the components to remove

Throws:

IllegalArgumentException - if there is a component whose non null parent is not this component

remove

default void remove(Collection<Component> components)

Removes the given child components from this component.

Parameters:

components - the components to remove

Throws:

IllegalArgumentException - if there is a component whose non null parent is not this component

removeAll

default void removeAll()

Removes all contents from this component, including child components, text content as well as child elements that have been added directly to this component using the Element API. It also removes the children added only at the client-side.

addComponentAtIndex

default void addComponentAtIndex(int index,
 Component component)

Adds the given component as a child of this component at the specific index.

In case the specified component has already been added to another parent, it will be removed from there and added to this one.

Parameters:

index - the index, where the component will be added. The index must be non-negative and may not exceed the children count

component - the component to add, value should not be null

addComponentAsFirst

default void addComponentAsFirst(Component component)

Adds the given component as the first child of this component.

In case the specified component has already been added to another parent, it will be removed from there and added to this one.

Parameters:

component - the component to add, value should not be null

bindChildren

default <T extends @Nullable Object,
S extends Signal<T>>
void bindChildren(Signal<List<S>> list,
 SerializableFunction<S,Component> childFactory)

Binds a list Signal to this component using a child component factory. Each item Signal in the list corresponds to a child component within this component.

This component is automatically updated to reflect the structure of the list. Changes to the list, such as additions, removals, or reordering, will update this component's children accordingly.

This component must not contain any children that are not part of the list. If this component has existing children when this method is called, or if it contains unrelated children after the list changes, an IllegalStateException will be thrown.

New child components are created using the provided childFactory function. This function takes a Signal from the list and returns a corresponding Component. It shouldn't return null. The Signal can be further bound to the returned component as needed. Note that childFactory is run inside a Effect, and therefore Signal.get() calls makes effect re-run automatically on signal value change.

Example of usage:

 SharedListSignal<String> taskList = new SharedListSignal<>(String.class);

 UnorderedList component = new UnorderedList();

 component.bindChildren(taskList, ListItem::new);
 

Note: The default implementation adds children directly to the component’s element using the Element API and does not invoke add(Component...). Components that override add or manage children indirectly must override this method to provide a suitable implementation or explicitly disable it.

Type Parameters:

T - the value type of the Signals in the list

S - the type of the Signals in the list

Parameters:

list - list signal to bind to the parent, must not be null

childFactory - factory to create new component, must not be null

Throws:

IllegalStateException - thrown if this component isn't empty

BindingActiveException - thrown if a binding for children already exists