Select

Select allows users to choose a single value from a list of options presented in an overlay.

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Select<String> select = new Select<>();
select.setLabel("Sort by");
select.setItems("Most recent first", "Rating: high to low",
  "Rating: low to high", "Price: high to low", "Price: low to high");
select.setValue("Most recent first");

add(select);

The dropdown can be opened with a click, up/down arrow keys, or by typing the initial character for one of the options.

Common Input Field Features

Select includes all Text Field and shared input field features.

Dividers

Dividers can be used to group related options. Use dividers sparingly to avoid creating unnecessary visual clutter.

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Select<String> select = new Select<>();
select.setLabel("Sort by");
select.setItems("Most recent first", "Rating: high to low",
  "Rating: low to high", "Price: high to low", "Price: low to high");
select.addComponents("Most recent first", new Hr());
select.addComponents("Rating: low to high", new Hr());
select.setValue("Most recent first");

add(select);
Note
Use Combo Box for long lists
Please note that for large data sets it is preferable to use Combo Box instead of Select, as it allows users to filter the list of options.

Disabled Items

Items can be disabled. This prevents users from selecting them, while still showing that these items would be available for selection under different circumstances.

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Select<String> select = new Select<>();
select.setLabel("Size");
select.setItems("XS (out of stock)", "S", "M", "L", "XL");
select.setItemEnabledProvider(item -> !"XS (out of stock)".equals(item));
select.setValue("XL");

add(select);
Caution
Accessibility
Some assistive technologies might not announce disabled options.

Placeholder

Use the placeholder feature to provide an inline text prompt for the field. Do not create, or use, a separate item for this purpose.

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Select<String> select = new Select<>();
select.setLabel("Size");
select.setItems("XS", "S", "M", "L", "XL");
select.setPlaceholder("Select size");

add(select);

Empty Selection Item

An empty item can be set as the first option. Use it in cases where you want to allow users to clear their selection. The value of the empty item is represented as null.

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select.setEmptySelectionAllowed(true);

Customizing Empty Selection Caption

The label for the empty item is customizable.

The caption set replaces the placeholder for the empty selection item.

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select.setEmptySelectionAllowed(true);
select.setEmptySelectionCaption("Unknown size");

Custom Item Label

When using complex values, a label can be set to represent the item value as plain text.

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Select<Person> select = new Select<>();
select.setLabel("Assignee");
// Display full name of the person as item text and selected value label
select.setItemLabelGenerator(Person::getFullName);

List<Person> people = DataService.getPeople(5);
select.setItems(people);

When using custom item renderers with rich content, a label can be set to represent the item value when it is selected.

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Select<Person> select = new Select<>();
select.setLabel("Assignee");
// Use a custom renderer for items in the dropdown
select.setRenderer(SelectCustomRendererLabel.createPersonRenderer());
// Display full name of the person as selected value label
select.setItemLabelGenerator(Person::getFullName);

List<Person> people = DataService.getPeople(5);
select.setItems(people);
Note
Ensure item label generator handles null values

When using setItemLabelGenerator in combination with setEmptySelectionAllowed, ensure that the implementation is capable of handling null values, as the empty selection item has the value null.

select.setEmptySelectionAllowed(true);
select.setItemLabelGenerator(person -> {
  if (person == null) {
      return "No assignee";
  }
  return person.getFullName();
});

The same applies when using a data source that may contain null values.

Custom Item Presentation

Items can be rendered with rich content instead of plain text. This can be useful to provide information in a more legible fashion than appending it to the item text.

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Select<Person> select = new Select<>();
select.setLabel("Choose doctor");
select.setRenderer(new ComponentRenderer<>(person -> {
    FlexLayout wrapper = new FlexLayout();
    wrapper.setAlignItems(Alignment.CENTER);

    // NOTE
    // We are using inline styles here to keep the example simple.
    // We recommend placing CSS in a separate style sheet and to
    // encapsulating the styling in a new component.

    Image image = new Image();
    image.setSrc(person.getPictureUrl());
    image.setAlt("Portrait of " + person.getFirstName() + " " + person.getLastName());
    image.setWidth("var(--lumo-size-m)");
    image.getStyle().set("margin-right", "var(--lumo-space-s)");

    Div info = new Div();
    info.setText(person.getFirstName() + " " + person.getLastName());

    Div profession = new Div();
    profession.setText(person.getProfession());
    profession.getStyle().set("font-size", "var(--lumo-font-size-s)");
    profession.getStyle().set("color", "var(--lumo-secondary-text-color)");
    info.add(profession);

    wrapper.add(image, info);
    return wrapper;
}));
select.setItems(items);
add(select);

Best Practices

Set a Default Value

When applicable, set the most common choice as the default value.

Do Not Use as a Menu

Select is an input field component, not a generic menu component. Use Menu Bar to create overlays for actions.

ComponentUsage recommendations

Radio Button

Better accessibility than Select, as all options are visible without user interaction.

Combo Box

Filterable list of options. Appropriate for large sets of options. Supports lazy loading entry of custom values.

List Box

Scrollable inline list of options. Supports single and multi-select.

Menu Bar

Overlay menus for items that trigger actions.