"showMessageDialog" method in swing package

Code :

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import javax.swing.JOptionPane;
class my11{
	public static void main(String arg[]){
		JOptionPane.showMessageDialog(null,"Hello \n how are you? ");
	}
}

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Please be kind to reply, what are the other values that we can pass to call the above method except "null"

As taken from the Javadoc.

JOptionPane.showMessageDialog(parentComponent, message, title, messageType, icon)

Quote:

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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
icon an icon to display in the dialog that helps the user identify the kind of message that is being displayed

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// Json