java - Custom JOptionPane Icon -

java's "how make dialogs" tutorial shows code:

//custom title, custom icon joptionpane.showmessagedialog(frame, "eggs not supposed green.",         "inane custom dialog", joptionpane.information_message, icon); 

which create following dialog:

why joptionpane.information_message needed when icon changed icon parameter?

the flag indicates message style use on window decorations, see http://nadeausoftware.com/node/91#usinglookandfeelspecificwindowdecorations

from joptionpane class source code:

private static int stylefrommessagetype(int messagetype) {     switch (messagetype) {     case error_message:         return jrootpane.error_dialog;     case question_message:         return jrootpane.question_dialog;     case warning_message:         return jrootpane.warning_dialog;     case information_message:         return jrootpane.information_dialog;     case plain_message:     default:         return jrootpane.plain_dialog;     } } 

and in method showoptiondialog called showmessagedialog...

int style = stylefrommessagetype(messagetype); jdialog dialog = pane.createdialog(parentcomponent, title, style);