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Select

Source: TypeScript / Java
Select allows users to choose a single value from a list of options presented in an overlay.

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 drop-down menu can be opened with a click, up and down arrow keys, or by typing the initial character of one of the options.

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);

For large data sets, it’s preferable to use Combo Box instead of Select. This allows users to filter the list of options.

Disabled Items

Items can be disabled. This prevents users from selecting them, while still showing that the 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.

Overlay

You can customize the position and the width of the Select overlay, where the list of options is rendered. You can also add CSS class names to the overlay to customize its styles.

Overlay Position

The overlay is shown on top of the input field by default. You can configure the placement so that it doesn’t cover the input field.

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Select<String> select = new Select<>();
select.setNoVerticalOverlap(true);

Overlay Width

The overlay is as wide as the options in it and at least as wide as the input field. The overlay width can be overridden to any fixed width in cases where the default width is too narrow.

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Select<Person> select = new Select<>();
select.setOverlayWidth("350px");

Overlay Class Name

Like other field components with overlays, Select provides dedicated API to set a CSS class name on the overlay for styling. See Styling Component Instances for more information.

Select<String> select = new Select<>();
select.addOverlayClassName("locales");

Basic Features

The following features, common to most input field components, are supported:

Label

The label is used to identify the input field. It supports plain-text content, and its length is limited to the width of the field. Helpers and Tooltips can be used to provide additional information that doesn’t fit into the label.

Visible labels are strongly recommended for all input fields. In cases where the built-in label cannot be used, an external element can be associated as the field’s label through the aria-labelledby attribute. Fields without any visible label should include an invisible label for assistive technologies with the aria-label attribute.

Helper

Helpers are used to provide additional information that the user may need to enter in the field, such as format requirements or explanations of the field’s purpose below the field.

A style variant is available for rendering the helper above the field.

In addition to plain text, helpers can contain components and HTML elements. However, complex and interactive content is likely to have accessibility issues.

Tooltip

Tooltips are small text pop-ups displayed on hover, and on keyboard-focus. They can be used to provide additional information about a field. This can be useful in situations where an always visible Helper is not appropriate. Helpers are generally recommended in favor of tooltips, though, as they provide much better discoverability and mobile support. See the Tooltip documentation for more information.

Prefix

A prefix element — rendered at the start of the field — can be used to display units, icons, and similar visual cues to the field’s purpose or format.

Prefix elements typically don’t work well with assistive technologies like screen readers. Therefore, the information communicated by them should also be conveyed through other means, such as in a Label, a Helper or through ARIA attributes on the field itself.

External & Invisible Labels (ARIA)

Visible labels are strongly recommended for all input fields. In situations where the built-in label cannot be used, an external element can be associated as the field’s label through its element id. Fields without any visible label should be provided an invisible label for assistive technologies like screen readers.

<!-- Associates external element as label: -->
<label id="external-label">This is the label</label>
<vaadin-select accessible-name-ref="external-label">...

<!-- Invisible label for screen readers: -->
<vaadin-select accessible-name="This is the label">...
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Select<String> field = new Select<>();
field.setLabel("Label");
field.setHelperText("Helper text");
field.setPlaceholder("Placeholder");
field.setTooltipText("Tooltip text");
field.setPrefixComponent(VaadinIcon.VAADIN_H.create());

Read-Only & Disabled

Fields used to display values should be set to read-only mode to prevent editing. Read-only fields are focusable and visible to screen readers. They can display tooltips. Their values can be selected and copied.

Fields that are currently unavailable should be disabled. The reduced contrast of disabled fields makes them inappropriate for displaying information. They can’t be focused or display tooltips. They’re invisible to screen readers, and their values cannot be selected and copied.

Disabled fields can be useful in situations where they can become enabled based on some user action. Consider hiding fields entirely if there’s nothing the user can do to make them editable.

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Select<String> readonlyField = new Select<>();
readonlyField.setReadOnly(true);
Select<String> disabledField = new Select<>();
disabledField.setEnabled(false);

Style Variants

The following style variants can be applied:

Text Alignment

Three different text alignments are supported: left, which is the default; center; and right.

Right-alignment is recommended for numerical values when presented in vertical groups. This tends to aid interpretation and comparison of values.

Small Variant

The small variant can be used to make individual fields more compact. The default size of fields can be customized with style properties.

Helper Above Field

The helper can be rendered above the field, and below the label.

Borders

Borders can be applied to the field surface by providing a value (e.g., 1px) to the --vaadin-input-field-border-width CSS property. This can be applied globally to all input fields using the html selector, or to individual component instances. Borders are required to achieve WCAG 2.1 level AA conformant color contrast with the default Lumo styling of fields.

You can override the default border color with the --vaadin-input-field-border-color property.

Open in a
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Select<String> field = new Select<>();
field.addThemeVariants(SelectVariant.LUMO_SMALL,
        SelectVariant.LUMO_ALIGN_RIGHT,
        SelectVariant.LUMO_HELPER_ABOVE_FIELD);
field.getStyle().set("--vaadin-input-field-border-width", "1px");

Placeholder

Use the placeholder feature to provide an inline text prompt for the field. Don’t create or use a separate item for this purpose.

Open in a
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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 (Flow)

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 that you 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’s 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
Flow-Specific

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

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

Don’t Use as a Menu

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

Component Usage Recommendation

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.

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