ComboFixed2
ComboFixed2<T> is a drop-down over a list of values you state yourself, each
with the label to show for it.
ComboFixed2<String> medium = new ComboFixed2<>(List.of(
new ValueLabelPair<>("cd", "Compact disc"),
new ValueLabelPair<>("lp", "Vinyl LP"),
new ValueLabelPair<>("dl", "Download")
));
FormBuilder fb = new FormBuilder(cp);
fb.label("Medium").control(medium);
Value and label
The list is a List<ValueLabelPair<T>>: the pair carries the value the control
hands back and the text the user reads. That is the whole difference with
ComboLookup2, which takes the values themselves and
works out their labels from metadata.
ComboFixed2<T> therefore has two types inside it - it extends
ComboComponentBase2<ValueLabelPair<T>, T> - but from the outside it is an
IControl<T>: getValue() hands back a T.
Building one from an enum
ComboFixed2<Medium> medium = ComboFixed2.createEnumCombo(Medium.class);
| Method | What you get |
|---|---|
createEnumCombo(Class, exceptions...) |
every constant except the exceptions, sorted by label |
createEnumCombo(Class, boolean sorted, exceptions...) |
the same, in declaration order when sorted is false |
createEnumCombo(List<T>) / createEnumCombo(T...) |
exactly these constants, in that order |
createCombo(T... items) |
any objects at all, labelled by their domain label or toString() |
createCombo(List<T>, QField<T,?> labelField) |
any objects, labelled by one of their properties |
createComboFor(PropertyMetaModel, editable) |
a combo for a property, from its domain values and metadata |
The enum labels come from the .properties file next to the enum
(Vinyl.label=Vinyl LP). A combo built from a property can do better: it uses
that property's own bundle first, so the same enum value can read differently in
two places.
The empty choice
A combo that is not mandatory renders an extra, empty option at the top - that
is how it can hand back null. What that option says is up to you:
combo.setEmptyText("- pick a medium -");
A mandatory combo renders the empty option only while it has no valid value
at the moment it is built: build it with a value and the user cannot
un-choose. Picking a value in the browser does not take the empty choice away -
the option list is only rewritten when the control is rebuilt. getValue() on
an empty mandatory combo reports Mandatory field and throws.
The rest of the control
| Method | What it does |
|---|---|
setValue(T) / getValue() |
the value; it must be one of the list |
setData(List<ValueLabelPair<T>>) |
replace the whole list (this rebuilds the control) |
setMandatory(boolean) |
see above; it rebuilds, because the empty option changes |
setReadOnly(boolean) |
renders as the label of its value, no select element at all |
setDisabled(boolean) / setDisabledBecause(String) |
a greyed-out select |
setOnValueChanged(...) |
called when another option is picked |
immediate() |
post the change even without a handler |
addExtraButton(icon, title, click) |
a small button right of the combo |
setRenderer(IRenderInto<ValueLabelPair<T>>) |
draw the options yourself instead of showing the label |
A read-only combo is worth calling out: it is not a disabled select but plain text, so a read-only form reads as a form rather than as a wall of grey boxes.
From a property
fb.property(shipment, Shipment_.state()).control() gives a ComboFixed2 for a
boolean or an enum property with more than five domain values, and a
RadioGroup for one with five or fewer. Asking for
control(ComboFixed2.class) overrides the count. A boolean property gets Yes/No
from DomUI's own bundle, and a primitive boolean one is made mandatory as
well - it has no third state to offer.