Dialogs

Dialogs are small windows for focused interaction: messages, confirmations, and input prompts. Swing offers JOptionPane for the standard prebuilt dialogs (message, yes/no, input) and JDialog/JFrame for custom dialog layouts. In Jython both are straightforward Java API usage.

Message Dialogs

from javax.swing import JOptionPane, JFrame

frame = JFrame("Dialogs")
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
frame.setSize(300, 150)
frame.setVisible(True)

# informational
JOptionPane.showMessageDialog(frame, "Operation complete.")

# warning
JOptionPane.showMessageDialog(
    frame, "Disk almost full.", "Warning",
    JOptionPane.WARNING_MESSAGE)

# error
JOptionPane.showMessageDialog(
    frame, "File not found.", "Error",
    JOptionPane.ERROR_MESSAGE)

Yes/No and Option Dialogs

reply = JOptionPane.showConfirmDialog(
    frame, "Save changes before closing?",
    "Unsaved changes",
    JOptionPane.YES_NO_CANCEL_OPTION)
if reply == 0:      # YES_OPTION
    print("save")
elif reply == 1:    # NO_OPTION
    print("discard")
else:
    print("cancel")

choice = JOptionPane.showOptionDialog(
    frame, "Pick an action", "Action",
    0, 1, None,
    ["Import", "Export", "Cancel"], "Import")

Input Dialog

name = JOptionPane.showInputDialog(
    frame, "Your name:", "Greeting", "Ada")
if name:
    JOptionPane.showMessageDialog(frame, "Hello, " + name + "!")

A Custom Dialog

from javax.swing import (JDialog, JTextField, JButton,
                         JOptionPane, GridLayout)
from java.awt import GridBagLayout, GridBagConstraints
import java.awt as awt

def make_login_dialog(parent):
    dlg = JDialog(parent, "Login", True)  # modal
    dlg.setLayout(GridBagLayout())
    g = GridBagConstraints()
    g.insets = awt.Insets(4, 4, 4, 4)

    user_field = JTextField(14)
    pass_field = JTextField(14)
    pass_field.setEchoChar("*")

    g.gridx, g.gridy = 0, 0
    dlg.add(awt.Label("User:"), g)
    g.gridx = 1
    dlg.add(user_field, g)
    g.gridx, g.gridy = 0, 1
    dlg.add(awt.Label("Pass:"), g)
    g.gridx = 1
    dlg.add(pass_field, g)

    result = {"ok": False}

    def on_ok(e):
        if user_field.getText() and pass_field.getText():
            result["ok"] = True
            dlg.dispose()

    ok = JButton("OK")
    ok.addActionListener(on_ok)
    g.gridx, g.gridy = 0, 2
    g.gridwidth = 2
    dlg.add(ok, g)

    dlg.pack()
    dlg.setLocationRelativeTo(parent)
    dlg.setVisible(True)
    return result["ok"], user_field.getText(), pass_field.getText()

# usage:
# ok, u, p = make_login_dialog(frame)

Modal vs Modeless

• Modal (JOptionPane dialogs, JDialog(..., True)): blocks the parent until dismissed - use for required decisions.
• Modeless (JDialog(..., False)): coexists with the parent - use for tool windows and inspectors.

Summary

Use JOptionPane for standard dialogs - showMessageDialog for info/warn/error, showConfirmDialog and showOptionDialog for choices, showInputDialog for quick text input - and build custom modal or modeless JDialogs with the same layout managers and listeners as any window. Modality is the key decision: block the parent only when the user must answer before continuing.