Hello fellow NL Java programmers, have been given a final project at school.it a supermarket POS system.Have created the interface and database etc.but am currently having logical problems.
1. I have a Button called NewSale which calls JInternalFrame newsale, while a sale is in the process meaning the internalframe is showing and enabled,in case the user click the NewSales again,it should trigger with JOptionpane "A new Sale is in the process and not completed yet.Click new to start a new sale or resume to return to the present sale", thanks guys, oladipupo

you can set a counter each time the user clicks the newsale button,then if he clicks it again,that means the jinternalframe is already activated and you handle clicks after counter is > 1 to mean he has not finshed the current sale.when he finshes the current sale,reset the counter to zero to capture the next sale internaljframe

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if i can visualize what you are saying,while the newsale jinternalframe is enabled,why dont you disable the newsale button when the newsale jinternalframe comes up (so that user will not even have access and place a cancelbutton on the newsale jinternal frame which will enable the user to cancel the current sale.you could do that with optionbar or a popup menu and then enable the newsale button when user has finished the current sale or canceled it unles you want the user to be able to record mutiple sales at the same time.