What is the interface in java programming language? why do we need to use it?

Draw the hierarchy chart and design the logic for a program that calculates service charges for hazel's housecleaning service. the program contains housekeeping, detail loop, and end-of-job modules. the main program declares any needed global variables and constants and calls the other modules. the housekeeping module displays a prompt for and accepts a customer's last name. while the user does not enter for the name, the detail loop accepts the number of bathrooms and the number of other rooms to be cleaned. the service charge is computed as $40 plus $15 for each bathroom and $10 for each of the other rooms. the detail loop also displays the service charge and then prompts the user for the next customer's name. the end-of-job module, which executes after the user enters the sentinel value for the name, displays a message that indicates the program is complete.

Technician a says that a dry sump system uses no oil storage sump under the engine. technician b says that a wet sump system uses no oil storage sump under the engine. who is correct?

Write an essay on online collaboration, how to do it, the challenges, resolving the challenges, and consider whether the risks are greater than rewards. ( need )