[[components.selection.databinding]]
== Binding Selection Components to Data
-The selection components are strongly coupled with the Vaadin Data Model,
-described in
+The selection components typically bound to list of items obtained from backend system.
+You can give the the list of items in the constructor or set it set
+[methodname]#setItems()#. Read more in
<<dummy/../../../framework/datamodel/datamodel-overview.asciidoc#datamodel.overview,"Binding
-Components to Data">>. The selectable items in all selection components are
-objects that implement the [classname]#Item# interface. The items are contained
-in a [classname]#Container#.
-
-All selection components are containers themselves and simply forward all
-container operations to the underlying container data source. You can give the
-container in the constructor or set it set
-[methodname]#setContainerDataSource()#. This is further described in
-<<dummy/../../../framework/datamodel/datamodel-container#datamodel.container.intro,"Basic
-Use of Containers">>.
-
-
-[source, java]
-----
-// Have a container data source of some kind
-IndexedContainer container = new IndexedContainer();
-container.addContainerProperty("name", String.class, null);
-...
-
-// Create a selection component bound to the container
-OptionGroup group = new OptionGroup("My Select", container);
-----
-
-If you do not bind a selection component to a container data source, a default
-container is used. It is usually either an [classname]#IndexedContainer# or a
-[classname]#HierarchicalContainer#.
-
-The current selection of a selection component is bound to the
-[classname]#Property# interface, so you can get the current selection as the
-value of the selection component. Also selection changes are handled as value
-change events, as is described later.
+Components to Data">>.
+You can get the current selection as the
+value of the selection component using [methodname]#getSelected# defined in
+[interfacename]#Select# interface. Also selection changes are handled as
+selection change events, as is described later.
[[components.selection.adding]]
== Adding New Items
-New items are added with the [methodname]#addItem()# method defined in the
-[classname]#Container# interface, described in
-<<dummy/../../../framework/datamodel/datamodel-container#datamodel.container.intro,"Basic
-Use of Containers">>.
-
-
-[source, java]
-----
-// Create a selection component
-ComboBox select = new ComboBox("My ComboBox");
-
-// Add items with given item IDs
-select.addItem("Mercury");
-select.addItem("Venus");
-select.addItem("Earth");
-----
-
-The [methodname]#addItem()# method creates an empty [classname]#Item#, which is
-identified by its __item identifier__ (IID) object, given as the parameter. This
-item ID is by default used also as the caption of the item, as described in more
-detail later.
-
-We emphasize that [methodname]#addItem()# is a factory method that __takes an
-item ID, not the actual item__ as the parameter - the item is returned by the
-method. The item is of a type that is specific to the container and has itself
-little relevance for most selection components, as the properties of an item may
-not be used in any way (except in [classname]#Table#), only the item ID.
-
-The item identifier is typically a string, in which case it can be used as the
-caption, but can be any object type. We could as well have given integers for
-the item identifiers and set the captions explicitly with
-[methodname]#setItemCaption()#. You could also add an item with the
-parameterless [methodname]#addItem()#, which returns an automatically generated
-item ID.
-
+New items are added with the [methodname]#addItems()# method.
[source, java]
----
// Create a selection component
-ComboBox select = new ComboBox("My Select");
+ComboBox<String> select = new ComboBox<>("Select a planet");
-// Add an item with a generated ID
-Object itemId = select.addItem();
-select.setItemCaption(itemId, "The Sun");
-
-// Select the item
-select.setValue(itemId);
+// Add items to select
+select.setItems("Mercury","Venus","Earth");
----
-Some container types may support passing the actual data object to the add
-method. For example, you can add items to a [classname]#BeanItemContainer# with
-[methodname]#addBean()#. Such implementations can use a separate item ID object,
-or the data object itself as the item ID, as is done in [methodname]#addBean()#.
-In the latter case you can not depend on the default way of acquiring the item
-caption; see the description of the different caption modes later.
-
-The next section describes the different options for determining the item
-captions.
-
-
[[components.selection.captions]]
== Item Captions
-The displayed captions of items in a selection component can be set explicitly
-with [methodname]#setItemCaption()# or determined from the item IDs or item
-properties. The caption determination is defined with the __caption mode__, any
-of the modes in the [classname]#AbstractSelect.ItemCaptionMode# enum, which you
-can set with [methodname]#setItemCaptionMode()#. The default mode is
-[parameter]#EXPLICIT_DEFAULTS_ID#, which uses the item identifiers for the
-captions, unless given explicitly.
-
-In addition to a caption, an item can have an icon. The icon is set with
-[methodname]#setItemIcon()#.
-
-The caption modes defined in [classname]#ItemCaptionMode# are the following:
-
-EXPLICIT_DEFAULTS_ID:: This is the default caption mode and its flexibility allows using it in most
-cases. By default, the item identifier will be used as the caption. The
-identifier object does not necessarily have to be a string; the caption is
-retrieved with [methodname]#toString()# method. If the caption is specified
-explicitly with [methodname]#setItemCaption()#, it overrides the item
-identifier.
+The items are typically a strings, in which case they can be used as the
+caption, but can be any object type. We could as well have given Planet instances
+for the items and use captions generated based on them
+[methodname]#setItemCaptionProvider()# method.
-+
[source, java]
----
+// List of Planet objects
+List<Planet> planets = new ArrayList<>();
+planets.add(new Planet("Mercury"));
+planets.add(new Planet("Venus"));
+planets.add(new Planet("Earth"));
+
// Create a selection component
-ComboBox select = new ComboBox("Moons of Mars");
-select.setItemCaptionMode(
- ItemCaptionMode.EXPLICIT_DEFAULTS_ID);
+ComboBox<Planet> select = new ComboBox<>("My Select");
-// The given item ID is also used as the caption
-select.addItem(new Integer(1));
+// Add an items to the ComboBox
+select.setItems(planets);
-// Set item caption for this item explicitly
-select.addItem(2); // same as "new Integer(2)"
-select.setItemCaption(2, "Deimos");
+select.setItemCaptionProvider(planet -> planet.getName());
+// or even select.setItemCaptionProvider(Planet::getName);
+
+// Select the first
+select.select(planets.get(0));
----
-EXPLICIT:: Captions must be explicitly specified with [methodname]#setItemCaption()#. If
-they are not, the caption will be empty. Such items with empty captions will
-nevertheless be displayed in the selection component as empty items. If they
-have an icon, they will be visible.
-ICON_ONLY:: Only icons are shown, captions are hidden.
+In addition to a caption, an item can have an icon. The icon is set with
+[methodname]#setItemIconProvider()#.
-ID:: String representation of the item identifier object is used as caption. This is
-useful when the identifier is a string, and also when the identifier is an
-complex object that has a string representation. For example:
+Typical use cases for captions are:
+
+Using the items as the caption: the caption is
+retrieved with [methodname]#toString()# method from the item. This is useful
+for simple objects like String or Integers, but also for objects that have
+human readable output for [methodname]#toString()# .
+
[source, java]
----
-ComboBox select = new ComboBox("Inner Planets");
-select.setItemCaptionMode(ItemCaptionMode.ID);
+ComboBox<Planet> select = new ComboBox<>("Inner Planets");
// A class that implements toString()
-class PlanetId extends Object
- implements Serializable {
+class Planet implements Serializable {
String planetName;
- PlanetId (String name) {
+ Planet(String name) {
planetName = name;
}
+
public String toString () {
return "The Planet " + planetName;
}
}
-// Use such objects as item identifiers
-String planets[] = {"Mercury", "Venus",
- "Earth", "Mars"};
-for (int i=0; i<planets.length; i++)
- select.addItem(new PlanetId(planets[i]));
+// Use such objects as items
+List<Planet> planets = new ArrayList<>();
+planets.add(new Planet("Mercury"));
+planets.add(new Planet("Venus"));
+planets.add(new Planet("Earth"));
+
+select.addItems(planets);
----
+Using a field of a item as caption: the caption is retrieved using the
+[interfacename]#ItemCaptionProvider# typically given as Java 8 lambda:
+
+
+
INDEX::
Index number of item is used as caption.
This caption mode is applicable only to data sources that implement the [interfacename]#Container.Indexed# interface.
+
[source, java]
----
-/** A bean with a "name" property. */
-public class Planet implements Serializable {
- int id;
- String name;
-
- public Planet(int id, String name) {
- this.id = id;
- this.name = name;
+// A class that implements toString()
+class Planet implements Serializable {
+ Integer id;
+ String planetName;
+
+ Planet(Integer id, String name) {
+ this.id = id
+ this.planetName = name;
+ }
+
+ public String toString () {
+ return "The Planet " + planetName;
+ }
+
+ public Integer getId () {
+ return id;
+ }
+
+
+ public String getName () {
+ return planetName;
}
- ... setters and getters ...
}
-public void captionproperty(
- VerticalLayout layout) {
- // Have a bean container to put the beans in
- BeanItemContainer<Planet> container =
- new BeanItemContainer<Planet>(
- Planet.class);
-
- // Put some example data in it
- container.addItem(
- new Planet(1, "Mercury"));
- container.addItem(new Planet(2, "Venus"));
- container.addItem(new Planet(3, "Earth"));
- container.addItem(new Planet(4, "Mars"));
-
- // Create a selection component bound
- // to the container
- ComboBox select = new ComboBox("Planets",
- container);
-
- // Set the caption mode to read the
- // caption directly from the 'name'
- // property of the bean
- select.setItemCaptionMode(
- ItemCaptionMode.PROPERTY);
- select.setItemCaptionPropertyId("name");
-
- ...
+// Put some example data
+List<Planet> planets = new ArrayList<>();
+planets.add(new Planet(1, "Mercury"));
+planets.add(new Planet(2, "Venus"));
+planets.add(new Planet(3, "Earth"));
+planets.add(new Planet(4, "Mars"));
+
+// Create a selection component
+ComboBox<Planet> select = new ComboBox<>("Planets");
+
+// Set the caption provider to read the
+// caption directly from the 'name'
+// property of the bean
+select.setItemCaptionProvider(Planet::getName);
----
[[components.selection.getset]]
== Getting and Setting Selection
-A selection component provides the current selection as the property of the
-component (with the [classname]#Property# interface). The property value is an
-item identifier object that identifies the selected item. You can get the
-identifier with [methodname]#getValue()# of the [classname]#Property# interface.
+You can get the item with [methodname]#getSelected()# of the
+[classname]#Select# interface that returns collection of selected items.
+You can select an item with the corresponding [methodname]#select()# method.
-You can select an item with the corresponding [methodname]#setValue()# method.
-In multiselect mode, the property will be an unmodifiable set of item
-identifiers. If no item is selected, the property will be [parameter]#null# in
-single selection mode or an empty collection in multiselect mode.
+In multiselect mode, the [methodname]#getSelected()# returns an unmodifiable
+set of items. If no item is selected, the select will be an empty collection.
The [classname]#ComboBox# and [classname]#NativeSelect# will show empty
-selection when no actual item is selected. This is the __null selection item
-identifier__. You can set an alternative ID with
-[methodname]#setNullSelectionItemId()#. Setting the alternative null ID is
-merely a visual text; the [methodname]#getValue()# will still return
-[parameter]#null# value if no item is selected, or an empty set in multiselect
-mode.
+selection when no actual item is selected.
[[components.selection.valuechange]]
== Handling Selection Changes
-The item identifier of the currently selected item will be set as the property
-of the selection component. You can access it with the [methodname]#getValue()#
-method of the [classname]#Property# interface of the component. Also, when
-handling selection changes with a [classname]#Property.ValueChangeListener#, the
-[classname]#ValueChangeEvent# will have the selected item as the property of the
-event, accessible with the [methodname]#getProperty()# method.
+You can access currently selected item with the [methodname]#getSelected()# or
+[methodname]#getFirstSelected()# method of the component. Also, when
+handling selection changes with a
+[classname]#SelectionChangeListener#, the
+[classname]#SelectionChange# will have the selected items of the event.
[source, java]
----
// Create a selection component with some items
-ComboBox select = new ComboBox("My Select");
-select.addItems("Io", "Europa", "Ganymedes", "Callisto");
+ComboBox<String> select = new ComboBox<>("My Select");
+select.setItems("Io", "Europa", "Ganymedes", "Callisto");
// Handle selection change
-select.addValueChangeListener(event -> // Java 8
+select.addSelectionChangeListener(event ->
layout.addComponent(new Label("Selected " +
- event.getProperty().getValue())));
+ event.getSelected())));
----
The result of user interaction is shown in
[[components.selection.newitems]]
== Allowing Adding New Items
-Some selection components can allow the user to add new items. Currently, only
-[classname]#ComboBox# allows it, when the user types in a value and presses
-kbd:[Enter]. You need to enable the mode with [methodname]#setNewItemsAllowed(true)#.
-Setting the component also in immediate mode may be necessary, as otherwise the
-item would not be added immediately when the user interacts with the component,
-but after some other component causes a server
-request.
-// TODO This could be a bug
+[classname]#ComboBox# allows the user to add new items, when the user types
+in a value and presses kbd:[Enter]. You need to enable this with
+[methodname]#setNewItemHandler()#.
-[source, java]
-----
-myselect.setNewItemsAllowed(true);
-myselect.setImmediate(true);
-----
-
-The user interface for adding new items depends on the selection component. The
-regular [classname]#ComboBox# component allows you to simply type the new item
-in the combo box and hit kbd:[Enter] to add it.
-
-Adding new items is not possible if the selection component is read-only or is
-bound to a [classname]#Container# that does not allow adding new items. An
+Adding new items is not possible if the selection component is read-only. An
attempt to do so may result in an exception.
[[components.selection.newitems.handling]]
=== Handling New Items
Adding new items is handled by a [interfacename]#NewItemHandler#, which gets the
-item caption string as parameter for the [methodname]#addNewItem()# method. The
-default implementation, [classname]#DefaultNewItemHandler#, checks for read-only
-state, adds the item using the entered caption as the item ID, and if the
-selection component gets the captions from a property, copies the caption to
-that property. It also selects the item. The default implementation may not be
-suitable for all container types, in which case you need to define a custom
-handler. For example, a [classname]#BeanItemContainer# expects the items to have
-the bean object itself as the ID, not a string.
+item caption string as parameter for the [methodname]#addNewItem()# method.
ifdef::web[]
[source, java]
----
-// Have a bean container to put the beans in
-final BeanItemContainer<Planet> container =
- new BeanItemContainer<Planet>(Planet.class);
+// List of planets
+List<Planet> planets = new ArrayList<>();
+planets.add(new Planet(1, "Mercury"));
+planets.add(new Planet(2, "Venus"));
+planets.add(new Planet(3, "Earth"));
+planets.add(new Planet(4, "Mars"));
-// Put some example data in it
-container.addItem(new Planet(1, "Mercury"));
-container.addItem(new Planet(2, "Venus"));
-container.addItem(new Planet(3, "Earth"));
-container.addItem(new Planet(4, "Mars"));
-
-final ComboBox select =
- new ComboBox("Select or Add a Planet", container);
-select.setNullSelectionAllowed(false);
+ComboBox<Planet> select =
+ new ComboBox<>("Select or Add a Planet");
+select.setItems(planets);
// Use the name property for item captions
-select.setItemCaptionPropertyId("name");
+select.setItemCaptionProvider(Planet::getName);
-// Allow adding new items
-select.setNewItemsAllowed(true);
-select.setImmediate(true);
+// Allow adding new items and add
+// handling for new items
+select.setNewItemHandler(inputString -> {
-// Custom handling for new items
-select.setNewItemHandler(new NewItemHandler() {
- @Override
- public void addNewItem(String newItemCaption) {
- // Create a new bean - can't set all properties
- Planet newPlanet = new Planet(0, newItemCaption);
- container.addBean(newPlanet);
+ // Create a new bean - can't set all properties
+ Planet newPlanet = new Planet(0, inputString);
+ planets.add(newPlanet);
- // Remember to set the selection to the new item
- select.select(newPlanet);
+ // Update combobox content
+ select.setItems(planets);
- Notification.show("Added new planet called " +
- newItemCaption);
- }
+ // Remember to set the selection to the new item
+ select.select(newPlanet);
+
+ Notification.show("Added new planet called " +
+ inputString);
});
----
See the http://demo.vaadin.com/book-examples-vaadin7/book#component.select.combobox.newitemhandler[on-line example, window="_blank"].
endif::web[]
-
[[components.selection.multiple]]
== Multiple Selection
Some selection components, such as [classname]#OptionGroup# and
[classname]#ListSelect# support a multiple selection mode, which you can enable
-with [methodname]#setMultiSelect()#. For [classname]#TwinColSelect#, which is
-especially intended for multiple selection, it is enabled by default.
+with [methodname]#setSelectionMode(SelectionMode.MULTI)#.
+For [classname]#TwinColSelect#, which is especially intended for
+multiple selection, it is enabled by default.
[source, java]
----
-myselect.setMultiSelect(true);
+myselect.setSelectionMode(SelectionMode.MULTI);
----
-As in single selection mode, the property value of the component indicates the
-selection. In multiple selection mode, however, the property value is a
-[classname]#Collection# of the item IDs of the currently selected items. You can
-get and set the property with the [methodname]#getValue()# and
-[methodname]#setValue()# methods as usual.
+In multiple selection mode the [interfacename]#Select# value is a
+[classname]#Collection# of the items of the currently selected items.
+You can get and set the selection with the [methodname]#getSelected()# and
+[methodname]#setSelected()# methods as usual.
-A change in the selection will trigger a [classname]#ValueChangeEvent#, which
-you can handle with a [classname]#Propery.ValueChangeListener#. As usual, you
-should use [methodname]#setImmediate(true)# to trigger the event immediately
-when the user changes the selection. The following example shows how to handle
-selection changes with a listener.
+A change in the selection will trigger a [classname]#SelectionChange#, which
+you can handle with a [classname]#SelectionChangeListener#. The
+following example shows how to handle selection changes with a listener.
[source, java]
----
// A selection component with some items
-ListSelect select = new ListSelect("My Selection");
-select.addItems("Mercury", "Venus", "Earth",
+ListSelect<String> select = new ListSelect<>("My Selection");
+select.setItems("Mercury", "Venus", "Earth",
"Mars", "Jupiter", "Saturn", "Uranus", "Neptune");
// Multiple selection mode
-select.setMultiSelect(true);
+select.setSelectionMode(SelectionMode.MULTI);
// Feedback on value changes
-select.addValueChangeListener(
- new Property.ValueChangeListener() {
- public void valueChange(ValueChangeEvent event) {
+select.addSelectionChangeListener(event -> {
// Some feedback
layout.addComponent(new Label("Selected: " +
- event.getProperty().getValue().toString()));
+ event.getSelected()));
}
});
-select.setImmediate(true);
+
----
[[components.selection.item-icons]]
== Item Icons
-You can set an icon for each item with [methodname]#setItemIcon()#, or define an
-item property that provides the icon resource with
-[methodname]#setItemIconPropertyId()#, in a fashion similar to captions. Notice,
-however, that icons are not supported in [classname]#NativeSelect#,
-[classname]#TwinColSelect#, and some other selection components and modes. This
-is because HTML does not support images inside the native [literal]#++select++#
+You can set an icon for each item with [methodname]#setItemIconProvider()#,
+in a fashion similar to captions. Notice, however, that icons are not
+supported in [classname]#NativeSelect#, [classname]#TwinColSelect#, and
+some other selection components and modes. This is because HTML does not
+support images inside the native [literal]#++select++#
elements. Icons are also not really visually applicable.
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