// This example is from the book _Java in a Nutshell_ by David Flanagan.
// Written by David Flanagan.  Copyright (c) 1996 O'Reilly & Associates.
// You may study, use, modify, and distribute this example for any purpose.
// This example is provided WITHOUT WARRANTY either expressed or implied.

import java.awt.*;

public class YesNoDialog extends Dialog {
    public static final int NO = 0;
    public static final int YES = 1;
    public static final int CANCEL = -1;

    protected Button yes = null, no = null, cancel = null;
    protected MultiLineLabel label;
    
    public YesNoDialog(Frame parent, String title, String message,
               String yes_label, String no_label, String cancel_label)
    {
        // Create the window.
        super(parent, title, true);

        // Specify a LayoutManager for it
        this.setLayout(new BorderLayout(15, 15));
        
        // Put the message label in the middle of the window.
        label = new MultiLineLabel(message, 20, 20);
        this.add("Center", label);
        
        // Create a panel of buttons, center the row of buttons in
        // the panel, and put the pane at the bottom of the window.
        Panel p = new Panel();
        p.setLayout(new FlowLayout(FlowLayout.CENTER, 15, 15));
        if (yes_label != null) p.add(yes = new Button(yes_label));
        if (no_label != null)  p.add(no = new Button(no_label));
        if (cancel_label != null) p.add(cancel = new Button(cancel_label));
        this.add("South", p);

        // Set the window to its preferred size.
        this.pack();
    }
    
    // Handle button events by calling the answer() method.
    // Pass the appropriate constant value, depending on the button.
    public boolean action(Event e, Object arg)
    {
        if (e.target instanceof Button) {
            this.hide();
            this.dispose();
            if (e.target == yes) answer(YES);
            else if (e.target == no) answer(NO);
            else answer(CANCEL);
            return true;
        }
        else return false;
    }
    
    // Call yes(), no(), and cancel() methods depending on the button the
    // user clicked.  Subclasses define how the answer is processed by
    // overriding this method or the  yes(), no(), and cancel() methods.
    protected void answer(int answer) {
        switch(answer) {
            case YES: yes(); break;
            case NO:  no(); break;
            case CANCEL: cancel(); break;
        }
    }
    protected void yes() {}
    protected void no() {}
    protected void cancel() {}
}