Dialogs and modals

Dialogs are popup windows stacked on top of the current screen. In CrossFly the three main ones are Alert (confirmation), ActionSheet (list of actions) and Hint (ephemeral notice, the old “Toast”).

⚠️ Alert/ActionSheet respond through the BUTTONS, not through onAnswer

They extend Window (not Picker), so show(callback) returns no value. The user’s choice arrives through the button callback (buttonAction). (See Returning values.)

Complete example (copy, paste and run)

package com.exemplo;

import dev.crossfly.ui.*;
import dev.crossfly.ui.layout.*;
import dev.crossfly.ui.style.*;

/** Runnable main screen. Point the launcher (classname) and run: gradlew :lwjgl3:run */
public class MainWindow extends Window
{
   @Override
   public void onShow() throws Exception
   {
      super.onShow();
      setLayout(new VerticalLayout());

      // Alert — buttons in the constructor (0 = Cancel, 1 = Delete); action by index.
      Button excluir = new Button("Excluir item");
      excluir.onAction(c -> {
         Alert a = new Alert("Excluir", "Confirma a exclusão deste item?", "Cancelar", "Excluir");
         a.buttonAction(1, x -> Hint.show("Item excluído", 2000));   // Cancel (0) just closes
         // popup: sizes and dims the background via fluent WindowStyle
         a.getStyle().widthRatio(0.85f).fadeBackground(128).transition(UIConstants.Transition.FADE);
         a.show();
      });
      add(LAY_AUTO, excluir);

      // ActionSheet — 1st argument is the cancel text.
      Button compartilhar = new Button("Compartilhar");
      compartilhar.onAction(c -> {
         ActionSheet sheet = new ActionSheet("Cancelar", "E-mail", "Mensagem");
         sheet.buttonAction(0, x -> Hint.show("Enviado por e-mail", 2000));   // index 0 = Email
         sheet.buttonAction(1, x -> Hint.show("Enviado por SMS", 2000));      // index 1 = Message
         sheet.show();
      });
      add(LAY_AUTO, compartilhar);

      // Hint — ephemeral notice (delay in ms).
      Button avisar = new Button("Mostrar aviso");
      avisar.onAction(c -> Hint.show("Salvo com sucesso", 2000));
      add(LAY_AUTO, avisar);
   }
}

The snippets below show only the core (what goes inside onShow()). To run them, place them in the MainWindow skeleton above.

Alert (confirm / notify)

The button texts go in the constructor; each button’s action is wired by index with buttonAction:

// buttons: index 0 = "Cancel", index 1 = "Delete"
Alert a = new Alert("Excluir", "Confirma a exclusão deste item?", "Cancelar", "Excluir");
a.buttonAction(1, c -> excluirItem());   // action comes from here, NOT from show(cb); Cancel just closes
a.show();

ActionSheet (choose an action)

It also receives the texts in the constructor (the first argument is the cancel text):

ActionSheet sheet = new ActionSheet("Cancelar", "E-mail", "Mensagem");
sheet.buttonAction(0, c -> enviarPorEmail());   // index 0 = "Email"
sheet.buttonAction(1, c -> enviarPorSMS());     // index 1 = "Message"
sheet.cancelAction(c -> {});                     // optional: action on cancel
sheet.show();

Hint (ephemeral notice — replaces Toast/ToolTip)

Hint.show("Salvo com sucesso", 2000);     // disappears on its own

Configure popup appearance — WindowStyle

A popup is sized/positioned by the window’s WindowStyle. Useful fields:

getStyle().widthRatio = 0.85f;                       // 85% of the width
getStyle().fadeBackground = true;                     // dimmed background
getStyle().transition = UIConstants.Transition.FADE;  // appears with fade

Best practices

• Clear button labels (“Delete” instead of “OK”); put the destructive action last.
• Prefer Hint over Alert for non-blocking confirmations.

Common mistakes

• alert.show(cb) expecting the cb to fire — it doesn’t; wire the action with buttonAction(i, callback).
• Calling addButton(...)/addOption(...) — they don’t exist; the texts go in the constructor and the actions by index.
• Stacking several popups on the same event.

See also

• Returning values · The window stack
• Catalog: Alert · ActionSheet · Hint