Design and implement pharmacy system using queue

there will be 4 windows in the shop every window can accomadate 5 users queue is attached with every window user can get the window no after entering in the shop by entering their name if all windows have 5 user then user have to wait and added to another waiting queue whenever user is exit then the waiting user can get the window number sytem should details of every queue when ever user enter or exit .

In jAVA