showMessageDialog

public static void showMessageDialog(Component parentComponent,
Object message,
String title,
int messageType)
throws HeadlessException
Brings up a dialog that displays a message using a default icon determined by the messageType parameter.

Parameters:
parentComponent - determines the Frame in which the dialog is displayed; if null, or if the parentComponent has no Frame, a default Frame is used
message - the Object to display
title - the title string for the dialog
messageType - the type of message to be displayed: ERROR_MESSAGE, INFORMATION_MESSAGE, WARNING_MESSAGE, QUESTION_MESSAGE, or PLAIN_MESSAGE
Throws:
HeadlessException - if GraphicsEnvironment.isHeadless returns true
See Also:
GraphicsEnvironment.isHeadless()