# How to ask for confirmation before a destructive action

> Show a confirmation Alert with buttonAction, dim the background, and give feedback with Hint.

Source: https://crossfly.dev/docs/cookbook/nav/dialogo-confirmacao — CrossFly documentation. Full docs as one file: https://crossfly.dev/llms-full.txt

# How to ask for confirmation before a destructive action

**Purpose.** Before deleting/discarding something, show an `Alert` with two buttons (e.g., "Cancel" and "Delete"). Only run the destructive action in the confirmation button's callback.

## APIs used
- `new Alert(String title, String message, String... buttonTexts)` — creates the dialog. `Alert` **is a `Window`**; the buttons follow the active `Skin`.
- `Alert.buttonAction(int index, Component.Action action)` — sets a button's action (0-based index). Without an action, the button just closes (`hide()`).
- `Alert.show()` — stacks the dialog (modal push).
- `WindowStyle.fadeBackground(int alpha)` — dims the windows below (0–255). Get the style via `getStyle()`.
- `Hint.show(String message, int delayMs)` — shows a brief feedback toast.

## Complete example (copy, paste, and run)
```java
package com.exemplo;

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

/** Runnable main screen: a button triggers the confirmation Alert. */
public class MainWindow extends Window
{
   @Override
   public void onShow() throws Exception
   {
      super.onShow();
      setLayout(new VerticalLayout());

      add(new Label("Pedido #1234"));
      add(new Button("Excluir pedido").onAction(e -> confirmarExclusao()));
   }

   private void confirmarExclusao()
   {
      Alert alert = new Alert("Excluir pedido", "Esta ação não pode ser desfeita.", "Cancelar", "Excluir");

      // Darkens the background (0..255). The Alert's getStyle() is a WindowStyle.
      ((WindowStyle) alert.getStyle()).fadeBackground(150);

      // Index 0 = "Cancel": with no buttonAction, the button already closes the Alert on its own.
      // Index 1 = "Delete": destructive action + feedback.
      alert.buttonAction(1, e ->
      {
         excluirPedido();                 // destructive action
         alert.hide();                    // closes the dialog
         Hint.show("Pedido excluído", 1500);
      });

      alert.show();
   }

   private void excluirPedido()
   {
      // ... your deletion logic ...
   }
}
```

> The snippet below shows **only the core**. To run it, place it in the `MainWindow` skeleton above.

## Minimal snippet
```java
// verified in the source: Alert.buttonAction(idx, Action); WindowStyle.fadeBackground(int 0-255); Hint.show(msg, ms)
Alert alert = new Alert("Excluir pedido", "Esta ação não pode ser desfeita.", "Cancelar", "Excluir");

// Darkens the background (0..255). The Alert's getStyle() is a WindowStyle.
((WindowStyle) alert.getStyle()).fadeBackground(150);

// Index 0 = "Cancel": with no buttonAction, the button already closes the Alert on its own.
// Index 1 = "Delete": destructive action + feedback.
alert.buttonAction(1, e ->
{
   excluirPedido();                 // destructive action
   alert.hide();                    // closes the dialog
   Hint.show("Pedido excluído", 1500);
});

alert.show();
```

Details that avoid surprises:

- If you do **not** set `buttonAction` for a button, the Alert associates `onAction(e -> hide())` — the button closes the dialog and nothing more. That's why "Cancel" usually doesn't need `buttonAction`.
- **Always** put the destructive action in the confirmation button (here, index 1), never as the default behavior.
- `fadeBackground` takes an alpha of 0–255 (not 0xAARRGGBB). 150 gives a noticeable dimming without hiding the content.

## Go deeper
- [Dialogs and modals](/docs/ui/navigation/dialogs-and-modals)
- Sibling recipe: [Open and close a screen](/docs/cookbook/nav/abrir-tela)