Selection box

A selection box shows an immediately visible list allowing you to choose one (by default) or more options.

A WSelectionBox corresponds to an HTML <select> element.

WSelectionBox is a View widget (see also Model-View-Controller). By default a WStringListModel is used. With this model you can associate a single column of data to the displayed items. The member methods addItem(), insertItem() and removeItem() manipulate the model. You can set the model with setModel(). See the Combo box section for an example.

A model supports different roles like JWt.ItemDataRole.DisplayRole and JWt.ItemDataRole.UserRole. The suggestion text for an item in the drop-down box is associated with a JWt.ItemDataRole.DisplayRole. The value, which will be inserted in the line-edit, corresponding with a suggestion, is stored as JWt.ItemDataRole.UserRole) data. If no UserRole data is available, the behaviour defaults to inserting the suggestion text itself.

If you want to associate multiple data columns with an item from the combo box then you should assign another model to this control like WStandardItemModel or an implementation of WAbstractTableModel.

Note that there are still other models like WFormModel which and can be used to represent fields in a form.

Single option selection box

Example
source 
  void SelectionBoxSimple() {
    WContainerWidget container = new WContainerWidget();
    final WSelectionBox sb1 = new WSelectionBox((WContainerWidget) container);
    sb1.addItem("Heavy");
    sb1.addItem("Medium");
    sb1.addItem("Light");
    sb1.setCurrentIndex(1);
    sb1.setMargin(new WLength(10), EnumSet.of(Side.Right));
    final WText out = new WText("", (WContainerWidget) container);
    sb1.activated()
        .addListener(
            this,
            () -> {
              out.setText(new WString("You selected {1}.").arg(sb1.getCurrentText()));
            });
  }

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Multiple option selection box

Use shift and/or ctrl-click to select your pizza toppings...

Example
source 
  void SelectionBoxExtended() {
    WContainerWidget container = new WContainerWidget();
    final WSelectionBox sb2 = new WSelectionBox((WContainerWidget) container);
    sb2.addItem("Bacon");
    sb2.addItem("Cheese");
    sb2.addItem("Mushrooms");
    sb2.addItem("Green peppers");
    sb2.addItem("Ham");
    sb2.addItem("Pepperoni");
    sb2.addItem("Red peppers");
    sb2.addItem("Turkey");
    sb2.setSelectionMode(SelectionMode.Extended);
    Set<Integer> selection = new HashSet<Integer>();
    selection.add(1);
    selection.add(4);
    sb2.setSelectedIndexes(selection);
    sb2.setMargin(new WLength(10), EnumSet.of(Side.Right));
    final WText out = new WText((WContainerWidget) container);
    out.addStyleClass("help-block");
    sb2.activated()
        .addListener(
            this,
            () -> {
              WString selected = new WString();
              Set<Integer> newSelection = sb2.getSelectedIndexes();
              for (Iterator<Integer> it_it = newSelection.iterator(); it_it.hasNext(); ) {
                int it = it_it.next();
                if (!(selected.length() == 0)) {
                  selected.append(", ");
                }
                selected.append(sb2.getItemText(it));
              }
              out.setText(new WString("You choose {1}.").arg(selected));
            });
  }

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