Would it suppose any difference regarding overhead to write an import loading all the types within one package (import java.*); than just a specific type (i.e. import java.lang.ClassLoader)? Would the second one be a more advisable way to use than the other one?
There is not a performance or overhead cost to doing import .* vs importing specific types. However, I consider it to be a best practice to never use import .* My primary reason for this is I just like to keep things straightward, clean and with as little ambiguity as possible, and I think with a .* import you lose that.